CPU Governors, Hotplug drivers and GPU governors Explained Part 3 (Updated 23/12/16)
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Official XDA thread Of The Contributer: http://forum.xda-developers.com/member.php?u=5811506
Edited By ShivaY: http://forum.xda-developers.com/member.php?u=6704044
Guide Part 1 Link: http://forum.xda-developers.com/lenovo-a6000/how-to/cpu-governors-hotplug-drivers-gpu-t3528762
Guide Part 2 Link: http://forum.xda-developers.com/lenovo-a6000/how-to/cpu-governors-hotplug-drivers-gpu-t3528766
Guide Part 4 Link : http://forum.xda-developers.com/lenovo-a6000/how-to/cpu-governors-hotplug-drivers-gpu-t3528772
Here I've gathered some info for newcomers to the Android world.I've tried to keep it relatively simple. So if you want more info Comment Below
Recommended apps for manipulating kernel values:
1. Kernel Adiutor (Free to change governor and tune variables)
2. Kernel Adiutor-Mod (Free to change governor and tune variables)
3. Compatible kernel managers (e.g Stweaks, Synapse, UKM, etc.)
Hotplug drivers:
------------------------
mpdecision: Qualcomm's default hotplugging driver. One of the most widely used hotplug drivers in all android devices.
msm_hotplug: Great battery life, a custom qualcomm based hotplugging driver by myflux. It is a popular choice for many users.
intelliplug: Great balance between battery life and performance. It is also a popular hotplug driver from faux123.
Alucard: A great hotplugging driver by Alucard. It is known to be very battery friendly on devices.
Kt Auto Hotplug: A great hotplug driver by Ktoonsez. Pretty much a smarter mpdecision that has been optimized for quad-core devices.
Mako Hotplug: A new popular hotplugging driver found in Francokernel. This is a highly configurable driver that can be configured to use dual core for light-loads and quad-core for heavy loads.
Zen Decision: ZEN only onlines all cores when screen is on, it also takes thermal events into account and wont online any core back, if you're under 15% battery, or currently have a thermal event because of heat. So in the end it isn't a "real" hotplug driver, because it doesnt have any code for active hot plugging in it. That means you can't change its behavior.
Bricked Hotplug: Conservative hotplug driver by @showp1984. It is based on mpdecision but has been optimized for better balance between battery life and performance.
msm_sleeper: The main feature with this hotplug is that you can customize the screen off frequency. Two cores are always on, the third and fourth are independent and come online if needed. By default, if the load is over 80 for 400ms another core comes online. The third and/or fourth cores stay online as long as the load demands it or for a minimum of one second. While the screen is off, it goes down to a single core. Created by flar2.
Autosmp: A highly-efficient hotplug driver by @mrg666, works in-sync with the CPU governor to enable off-line cpu cores when the the CPU frequency reaches a high threshold and still more compute power is needed. Therefore, touch boost bloat is removed.
Thunderplug: A matured load-based hotplug driver with many tunables written from ground up by varun.chitre15. This hotplug is optimized for octa-core devices and also has support for 64bit CPUs.
Blu_plug: Dynamic hotplug from eng.stk's shamu kernel with screenoff battery saving.
cpuquiet: A hotplug driver by NVidia and ported to Snapdragon by maxwen. Originally made for NVidia tegra SOCs. It has a set of governors which keep the CPU running at optimal frequencies for battery and performance.
Fast hotplug: A hotplug driver from pec0ra's abricot kernel. It aims to be as lightweight as possible while also being highly customizable. However, it is still a WIP as it is known to have some stability issues.
Hima hotplug: An optimized hotplug driver based on intelliplug for big.LITTLE architecture. Found on chadouming's HTC One (M9) kernel, it takes advantage of the big and LITTLE CPU cores in order to provide 'butter smooth' performance.
State Helper: A hotplug driver by @neobuddy89 designed with the Nexus 6 in mind. It is highly configurable giving the user control over what CPUs to online based on what battery threshold levels have been set. Another feature that sets state helper apart from other hotplug methods is that it respects the thermal driver.
ZZmoove native hotplug: The hotplugging logic found in the ZZmoove governor. This isn't a standalone hotplug driver that can be used with other governors, the hotplugging is done by the governor which was common on older devices like the Samsung Galaxy S3. Native hotplugging may offer better stability and the governor should perform better in battery life and performance (your experience may vary) because it was designed for this specific governor.
Custom kernels may have their own hotplugging drivers but they are usually based on these ones.
Battery life:
mpdecision
Mako Hotplug
Intelliplug
Alucard
For performance:
mpdecision
For balanced:
Bricked Hotplug
Mako Hotplug
Intelliplug
mpdecision
GPU governors
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Simple: An open-source alternative to Qualcomm's closed-sourced governors. Developed by Faux123, it is highly customisable which will allow more fine-grained control over how the GPU scales up and down.
simple_ondemand: As the name implies, it is a simpler version of the CPU governor ondemand. simple_ondemand will ramp up the frequency when a load is detected. It has a good balance between performance and battery savings.
msm-adreno-tz: The default GPU governor used by Qualcomm for their adreno GPUs. It is based on the ondemand governor but is biased towards performance, therefore it should give better performance in games but less battery life.
Performance: As the name suggests, this keeps your GPU running at the max frequency. This is a governor if you want the best possible experience in games but you don't care about your battery life.
Powersave: Like the CPU governor, this keeps your GPU running at the lowest possible frequency. Best battery life, extreme lag in games.
Adreno Idler: It is an idling algorithm, an efficient workaround for msm-adreno-tz's overheads. Main goal is to lower the power consumptions while maintaining high-performance. Since msm-adreno-tz tends to *not* use the lowest frequency even on idle, Adreno idler replaces msm-adreno-tz's algorithm when it comes to calculating idle frequency(mostly by ondemand's method). The higher frequencies are not touched with this algorithm, so high-demanding games will (most likely) not suffer from worsened performance.
Userspace: This governor basically allows the user is able to set a desired frequency for the GPU to run at.
cpubw_hwmon: A hardware monitor based governor that attempts to determine bandwidth (BW) needed by CPU and other hardware. Because it samples bandwidth using polling intervals, it has been made to be biased towards performance to compensate for the possible slower response times during heavy loads.
MSM Cpufreq: The MSM CPUfreq governor determines the CPU to DDR bandwidth vote based on the current CPU frequency of all the active CPUs. In other words, this governor scales based on CPU usage which could mean more performance.
Governor types:
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All governors are coded to behave on certain principles which can affect the performance, battery life, stability of your device. I won't be updating this guide often because there is simply too many governors.
1) Ondemand Based:
Works on "ramp-up on high load" principle. CPU busy-time is taken into consideration for scaling decisions. Members: Ondemand, OndemandX, Intellidemand, Lazy, Lagfree, PegasusQ, HYPER, Wheatley, Hotplug, HotplugX, AbyssPlug, AbyssPlugv2, Nightmare, Sleepy.
2) Conservative Based:
Works by biasing the phone to prefer the lowest possible clockspeed as often as possible. Members: Conservative, Lionheart, LionheartX
3) Interactive Based:
Works on "make scaling decision when CPU comes out of idle-loop" principle. Members: Interactive, InteractiveX, Intelliactive, Lulzactive, Luzactiveq, Smartass, SmartassV2, SmartassH3, Brazilianwax, SavagedZen, Dyninteractive, Interactive Pro
4) Unique Category:
These do not fall into any other category above and/or possess unique attributes. Members: Userspace, Powersave, Performance, Min Max, ZZmove, MSM DCVS, IntelliMM
5) Hybrid Category:
These have a mix of two (or more) CPU governor behaviors. Members: Smartmax, Dancedance, Performance May Cry(PMC), Ktoonservative, KtoonservativeQ
Recommendations:
-----------------------------
For performance:
Interactive/InteractiveX
Intelliactive
Performance
ElementalX
HYPER
Lionheart/LionheartX
Blu_active
For battery life:
Ondemand
Conservative
Perfomance may cry (PMC)
Powersave
Smartmax
Intellimm
Alucard
For balanced battery life and performance:
Interactive/InteractiveX
Intelliactive
Ondemand/Ondemand
ElementalX
Yankactive/YanksusQ
PegasusQ
HYPER
Impulse
ZZMoove
For gaming:
Interactive/InteractiveX
Intelliactive
Performance
Lionheart/LionheartX
PegasusQ
ElementalX
Ondemand/OndemandX
HYPER
Individual-core CPU governor selection
Some kernels will allow you to set a governor on a per-core basis. This can introduce a wider range of configurations which can alter the scaling of specific part of the CPU. While there is no definite guidelines on how to achieve optimal settings, here are some configurations you can do:
All cores running the same governor:
This will give the best stability and the CPU will behave as expected. This is the stock default on all devices.
All cores running different governors:
You should probably avoid this because it can cause stabilities and can significantly affect the performance and battery life of your CPU. Most kernel developers may not even provide support because there are too many combinations to choose from and because of the risks associated with this setup.
big.LITTLE cores running two different governors:
Similar to the previous setup, this could cause instabilities on your device and could affect how well your CPU performs. It is better just to use the same governor across all cores but there have been some setups like this.
CPU governor tunables
--------------------------------
NOTE: If you don't have some of these tunables, you might have an older version of the governor/hotplug driver and/or the kernel maintainer has made modifications to it.
1. ONDEMAND
[ PARAMETERS ]
Quote:
i) sampling_rate - Measured in uS , this is how often the kernel look at the CPU usage and make decisions on what to do about the frequency. Higher values means CPU polls less often. For lower frequencies, this could be considered an advantage since it might not jump to next frequency very often, but for higher frequencies, the scale-down time will be increased.
ii) up_threshold - defines what the average CPU usage between the samplings of 'sampling_rate' needs to be for the kernel to make a decision on whether it should increase the frequency. For example when it is set to its default value of '95' it means that between the checking intervals the CPU needs to be on average more than 95% in use to then
decide that the CPU frequency needs to be increased.
iii) powersave_bias - Default value is 0. Setting a higher value will bias the governor towards lower frequency steps. Use this if you want CPU to spend less time on higher frequencies. A better alternative would be to underclock to a lower frequency than using powersave bias.
iv) sampling_down_factor - Determines how often CPU should stay at higher frequencies when truly busy. Default behavior is fast switching to lower frequencies (1). Having sampling_down_factor set to 1 makes no changes from existing behavior (for the non-modified ondemand), but having sampling_down_factor set to a value greater than 1 causes it to act as a multiplier for the scheduling interval for re-evaluating the load when the CPU is at its highest clock frequency (which is scaling_max_freq) due to high load. T
v) down_differential - Indirectly calculates the 'down-threshold' of Ondemand. After completing sampling-down-factor*sampling-rate at max frequency because of high load, governor samples the load again to calculate an estimate of the new target frequency in a way that the lowest frequency will be chosen that would not trigger up_threshold in the next sample. Because triggering up-threshold will again cause CPU to scale up to max frequency. During this choice down_differential is taken into account as a breathing room value. Target frequency is calculated as max_load_freq / (up_threshold - down_differential).
vi) freq_step - Whenever up-scaling logic is triggered the governor instructs the CPU to raise its frequency by freq_step percentage of max allowed frequency. (max policy * (freq step / 100)). Ex: max policy is 1600 and freq step 21%, it will scale 1600 * 21% = 336.
vii) ignore_nice_load - this parameter takes a value of '0' or '1'. When set to '0' (its default), all processes are counted towards the 'cpu utilisation' value. When set to '1', the processes that are run with a 'nice' value will not count (and thus be ignored) in the overall usage calculation. This is useful if you are running a CPU intensive calculation on your laptop that you do not care how long it takes to complete as you can 'nice' it and prevent it from taking part in the deciding process of whether to increase your CPU frequency.
viii) sampling_rate_min -
The sampling rate is limited by the HW transition latency:
transition_latency * 100
Or by kernel restrictions:
If CONFIG_NO_HZ is set, the limit is 10ms fixed.
If CONFIG_NO_HZ is not set or nohz=off boot parameter is used, the
limits depend on the CONFIG_HZ option:
HZ=1000: min=20000us (20ms)
HZ=250: min=80000us (80ms)
HZ=100: min=200000us (200ms)
The highest value of kernel and HW latency restrictions is shown and
used as the minimum sampling rate.
2. LULZACTIVE/LULZACTIVEQ
1. Initial Version:-
[ PARAMETERS ]
Quote:
i) down_sampling_time - Sampling time to scale cpu down.
ii) up_sampling_time - Sampling time to scale cpu up.
2. Second Version (LulzactiveQ):-
[ PARAMETERS ]
Quote:
i) inc_cpu_load - In previous version, this was 'hard-coded' to 60. Now it's user-configurable. The frequency at which governor scales CPU up/down. Load < inc_cpu_load: cpu scaled down. Load >= inc_cpu_load: cpu scaled up
ii) pump_up_step - No of scale up steps when load >= inc_cpu_load
iii) pump_down_step - No of scale down steps when load < inc_cpu_load
iv) screen_off_min_step - Steps in frequency table to be used when screen-off. Example: If available freqs are 1600 1400 1200 1000 800 500 200 100 (L0 to L7) and screen_off_min_step=5 then 100,200 and 500 (L5 to L7) will be used during screen-off depending on the demand.
v) up_sample_time - same as initial version. (Allowed values 10,000 to 50,000)
vi) down_sample_time - same as older version. (Allowed values 10,000 to 100,000)
3. SMARTASSV2
[ PARAMETERS ]
Quote:
i) awake_ideal_freq - The frequency until which CPU is scaled up rapidly on screen-awake (from sleep). Thereafter, scaling up is less aggressive.
ii) sleep_ideal_freq - The frequency until which CPU is scaled down rapidly when screen is turned off. Thereafter, scaling down is less aggressive.
iii) up_rate_us - The minimum amount of time to spend at a frequency before we can ramp up. (Ignored below awake-ideal frequency since governor needs to rapidly scale up to awake_ideal_freq when below it)
iv) down_rate_us - The minimum amount of time to spend at a frequency before we can ramp down. (Ignored above sleep-ideal frequency since governor needs to rapidly scale down to sleep_ideal_freq when above it)
v) max_cpu_load - Same as up_threshold in other governors.
vi) min_cpu_load - Same as down_threshold in other governors.
vii) ramp_down_step - Frequency delta when ramping down below the ideal frequency. Zero disables and will calculate ramp down according to load heuristic. When above the ideal frequency we always ramp down to the ideal freq.
viii) ramp_up_step - Frequency when ramping up above the ideal frequency. Zero disables and causes to always jump straight to max frequency. When below the ideal frequency we always ramp up to the ideal freq.
ix) sleep_wakeup_freq - The frequency to set when waking up from sleep. When sleep_ideal_freq=0 this will have no effect.
4. CONSERVATIVE
[ PARAMETERS ]
Quote:
Ondemand and conservative have some tunables in common, but with a few extras:
i) freq_step - this describes what percentage steps the cpu freq should be increased and decreased smoothly by. By default the cpu frequency will increase in 5% chunks of your maximum cpu frequency. You can change this value to anywhere between 0 and 100 where '0' will effectively lock your CPU at a speed regardless of its load whilst '100' will, in theory, make
it behave identically to the "ondemand" governor.
ii) down_threshold - same as the 'up_threshold' found for the "ondemand" governor but for the opposite direction. For example when set to its default value of '20' it means that if the CPU usage needs to be below 20% between samples to have the frequency decreased.
5. INTERACTIVE
1. Generic Version
[ PARAMETERS ]
Quote:
i) hispeed_freq - An intermediate "hi speed" at which to initially ramp when CPU load hits the value specified in go_hispeed_load. If load stays high for the amount of time specified in above_hispeed_delay, then speed may be bumped higher. Default is the maximum speed allowed by the policy at governor initialization time.
ii) go_hispeed_load - The CPU load at which to ramp to hispeed_freq. Default is 99%.
iii) min_sample_time - The minimum amount of time to spend at the current frequency before ramping down. Default is 80000 uS.
iv) timer_rate - Sample rate for reevaluating CPU load when the CPU is not idle. A deferrable timer is used, such that the CPU will not be woken from idle to service this timer until something else needs to run. (The maximum time to allow deferring this timer when not running at
minimum speed is configurable via timer_slack.) Default is 20000 uS.
v) target_loads - CPU load values used to adjust speed to influence the current CPU load toward that value. In general, the lower the target load, the more often the governor will raise CPU speeds to bring load below the target. The format is a single target load, optionally followed by pairs of CPU speeds and CPU loads to target at or above those speeds. Colons can be used between the speeds and associated target loads for readability. For example:
85 1000000:90 1700000:99
targets CPU load 85% below speed 1GHz, 90% at or above 1GHz, until 1.7GHz and above, at which load 99% is targeted. If speeds are specified these must appear in ascending order. Higher target load values are typically specified for higher speeds, that is, target load values also usually appear in an ascending order. The default is target load 90% for all speeds.
vi) above_highspeed_delay - When speed is at or above hispeed_freq, wait for this long before raising speed in response to continued high load. The format is a single delay value, optionally followed by pairs of CPU speeds and the delay to use at or above those speeds. Colons can be used between the speeds and associated delays for readability. For example:
80000 1300000:200000 1500000:40000
uses delay 80000 uS until CPU speed 1.3 GHz, at which speed delay 200000 uS is used until speed 1.5 GHz, at which speed (and above) delay 40000 uS is used. If speeds are specified these must appear in ascending order. Default is 20000 uS.
vii) timer_slack - Maximum additional time to defer handling the governor sampling timer beyond timer_rate when running at speeds above the minimum. For platforms that consume additional power at idle when CPUs are running at speeds greater than minimum, this places an upper bound on how long the timer will be deferred prior to re-evaluating load and dropping speed. For example, if timer_rate is 20000uS and timer_slack is 10000uS then timers will be deferred for up to 30msec when not at lowest speed. A value of -1 means defer timers
indefinitely at all speeds. Default is 80000 uS.
viii) boost - If non-zero, immediately boost speed of all CPUs to at least hispeed_freq until zero is written to this attribute. If zero, allow CPU speeds to drop below hispeed_freq according to load as usual. Default is zero.
ix) boostpulse - On each write, immediately boost speed of all CPUs to hispeed_freq for at least the period of time specified by boostpulse_duration, after which speeds are allowed to drop below hispeed_freq according to load as usual.
x) boostpulse_duration - Length of time to hold CPU speed at hispeed_freq on a write to boostpulse, before allowing speed to drop according to load as usual. Default is 80000 uS.
2. Qualcomm Version/Intelliactive/IntelliMM
[ PARAMETERS ]
Quote:
Has some tunables in common with the generic version but with a few extras:
i) Sync_freq Feature - This feature will cause a CPU frequency to stay above a particular
value sync_freq) if certain conditions (determined by the two nodes
up_threshold_any_cpu_freq and up_threshold_any_cpu_load) are satisfied
ii) Sync_freq - Only when both of the above conditions are satisfied will the CPU not drop
below this frequency value. The higher this value, the higher the frequency to jump will
be when the above conditions are satisfied.
iii) Up_threshold_any_cpu_freq - If the maximum frequency across all the CPUs is higher
than or equal to this frequency value, do not let the current CPU fall below sync_freq.
The higher this value, the fewer the chances to go to sync_freq.
iv) Up_threshold_any_cpu_load - If the maximum load across all the CPUs is higher than
or equal to this load value, do not let the current CPU fall below sync_freq. The higher
this value, the fewer the chances to go to sync_freq.
v) up_threshold_multi_core - When the up_threshold_multi_core is crossed, the cpu is ramped up to optimal_freq.
vi) optimal_freq - When more than one CPU is online and if up_threshold_multi_core has exceeded, the governor will ramp up the CPU to this frequency. This value should be less than your device's max CPU frequency.
6. Wheatley
[ PARAMETERS ]
Quote:
target_residency - The minimum average residency in µs which is considered acceptable for a proper efficient usage of the C4 state. Default is 10000 = 10ms.
allowed_misses - The number sampling intervals in a row the average residency is allowed to be lower than target_residency before the governor reduces the frequency. This ensures that the governor is not too aggressive in scaling down the frequency and reduces it just because some background process was temporarily causing a larger number of wakeups. The default is 5.
7. Darkness/Nightmare
[ PARAMETERS ]
Quote:
cpu_up_rate - No of samples to evaluate load to scale CPU frequency up. Increasing this value will increase the time spent on a frequency.
cpu_down_rate - No of samples to evaluate load to scale CPU frequency down. Increasing this value will increase the time spent on a frequency
inc_cpu_load_at_min_freq - This threshold is used as up threshold while sampling at frequencies is less than freq_for_responsiveness.
inc_cpu_load - The frequency at which governor scales CPU up.
dec_cpu_load - The frequency at which governor scales CPU down.
Guide Part 1 Link: http://forum.xda-developers.com/lenovo-a6000/how-to/cpu-governors-hotplug-drivers-gpu-t3528762
Guide Part 2 Link: http://forum.xda-developers.com/lenovo-a6000/how-to/cpu-governors-hotplug-drivers-gpu-t3528766
Guide Part 4 Link : http://forum.xda-developers.com/lenovo-a6000/how-to/cpu-governors-hotplug-drivers-gpu-t3528772
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Related
Thanks to deedii for posting this in another forum:
http://forum.xda-developers.com/show...65&postcount=2
Android CPU governors explained
1: OnDemand
2: OndemandX
3: Performance
4: Powersave
5: Conservative
6: Userspace
7: Min Max
8: Interactive
9: InteractiveX
10: Smartass
11: SmartassV2
12: Scary
13: Lagfree
14: Smoothass
15: Brazilianwax
16: SavagedZen
17: Lazy
18: Lionheart
19: LionheartX
20: Intellidemand
21: Hotplug
22: BadAss
23: Wheatley
1: OnDemand Governor:
This governor has a hair trigger for boosting clockspeed to the maximum speed set by the user. If the CPU load placed by the user abates, the OnDemand governor will slowly step back down through the kernel's frequency steppings until it settles at the lowest possible frequency, or the user executes another task to demand a ramp.
OnDemand has excellent interface fluidity because of its high-frequency bias, but it can also have a relatively negative effect on battery life versus other governors. OnDemand is commonly chosen by smartphone manufacturers because it is well-tested, reliable, and virtually guarantees the smoothest possible performance for the phone. This is so because users are vastly more likely to ***** about performance than they are the few hours of extra battery life another governor could have granted them.
This final fact is important to know before you read about the Interactive governor: OnDemand scales its clockspeed in a work queue context. In other words, once the task that triggered the clockspeed ramp is finished, OnDemand will attempt to move the clockspeed back to minimum. If the user executes another task that triggers OnDemand's ramp, the clockspeed will bounce from minimum to maximum. This can happen especially frequently if the user is multi-tasking. This, too, has negative implications for battery life.
2: OndemandX:
Basically an ondemand with suspend/wake profiles. This governor is supposed to be a battery friendly ondemand. When screen is off, max frequency is capped at 500 mhz. Even though ondemand is the default governor in many kernel and is considered safe/stable, the support for ondemand/ondemandX depends on CPU capability to do fast frequency switching which are very low latency frequency transitions. I have read somewhere that the performance of ondemand/ondemandx were significantly varying for different i/o schedulers. This is not true for most of the other governors. I personally feel ondemand/ondemandx goes best with SIO I/O scheduler.
3: Performance Governor:
This locks the phone's CPU at maximum frequency. While this may sound like an ugly idea, there is growing evidence to suggest that running a phone at its maximum frequency at all times will allow a faster race-to-idle. Race-to-idle is the process by which a phone completes a given task, such as syncing email, and returns the CPU to the extremely efficient low-power state. This still requires extensive testing, and a kernel that properly implements a given CPU's C-states (low power states).
4: Powersave Governor:
The opposite of the Performance governor, the Powersave governor locks the CPU frequency at the lowest frequency set by the user.
5:Conservative Governor:
This biases the phone to prefer the lowest possible clockspeed as often as possible. In other words, a larger and more persistent load must be placed on the CPU before the conservative governor will be prompted to raise the CPU clockspeed. Depending on how the developer has implemented this governor, and the minimum clockspeed chosen by the user, the conservative governor can introduce choppy performance. On the other hand, it can be good for battery life.
The Conservative Governor is also frequently described as a "slow OnDemand," if that helps to give you a more complete picture of its functionality.
6: Userspace Governor:
This governor, exceptionally rare for the world of mobile devices, allows any program executed by the user to set the CPU's operating frequency. This governor is more common amongst servers or desktop PCs where an application (like a power profile app) needs privileges to set the CPU clockspeed.
7: Min Max
well this governor makes use of only min & maximum frequency based on workload... no intermediate frequencies are used.
8: Interactive Governor:
Much like the OnDemand governor, the Interactive governor dynamically scales CPU clockspeed in response to the workload placed on the CPU by the user. This is where the similarities end. Interactive is significantly more responsive than OnDemand, because it's faster at scaling to maximum frequency.
Unlike OnDemand, which you'll recall scales clockspeed in the context of a work queue, Interactive scales the clockspeed over the course of a timer set arbitrarily by the kernel developer. In other words, if an application demands a ramp to maximum clockspeed (by placing 100% load on the CPU), a user can execute another task before the governor starts reducing CPU frequency. This can eliminate the frequency bouncing discussed in the OnDemand section. Because of this timer, Interactive is also better prepared to utilize intermediate clockspeeds that fall between the minimum and maximum CPU frequencies. This is another pro-battery life benefit of Interactive.
However, because Interactive is permitted to spend more time at maximum frequency than OnDemand (for device performance reasons), the battery-saving benefits discussed above are effectively negated. Long story short, Interactive offers better performance than OnDemand (some say the best performance of any governor) and negligibly different battery life.
Interactive also makes the assumption that a user turning the screen on will shortly be followed by the user interacting with some application on their device. Because of this, screen on triggers a ramp to maximum clockspeed, followed by the timer behavior described above.
9: InteractiveX Governor:
Created by kernel developer "Imoseyon," the InteractiveX governor is based heavily on the Interactive governor, enhanced with tuned timer parameters to better balance battery vs. performance. The InteractiveX governor's defining feature, however, is that it locks the CPU frequency to the user's lowest defined speed when the screen is off.
10: Smartass
Is based on the concept of the interactive governor.
I have always agreed that in theory the way interactive works – by taking over the idle loop – is very attractive. I have never managed to tweak it so it would behave decently in real life. Smartass is a complete rewrite of the code plus more. I think its a success. Performance is on par with the “old” minmax and I think smartass is a bit more responsive. Battery life is hard to quantify precisely but it does spend much more time at the lower frequencies.
Smartass will also cap the max frequency when sleeping to 352Mhz (or if your min frequency is higher than 352 – why?! – it will cap it to your min frequency). Lets take for example the 528/176 kernel, it will sleep at 352/176. No need for sleep profiles any more!"
11: SmartassV2:
Version 2 of the original smartass governor from Erasmux. Another favorite for many a people. The governor aim for an "ideal frequency", and ramp up more aggressively towards this freq and less aggressive after. It uses different ideal frequencies for screen on and screen off, namely awake_ideal_freq and sleep_ideal_freq. This governor scales down CPU very fast (to hit sleep_ideal_freq soon) while screen is off and scales up rapidly to awake_ideal_freq (500 mhz for GS2 by default) when screen is on. There's no upper limit for frequency while screen is off (unlike Smartass). So the entire frequency range is available for the governor to use during screen-on and screen-off state. The motto of this governor is a balance between performance and battery.
12: Scary
A new governor wrote based on conservative with some smartass features, it scales accordingly to conservatives laws. So it will start from the bottom, take a load sample, if it's above the upthreshold, ramp up only one speed at a time, and ramp down one at a time. It will automatically cap the off screen speeds to 245Mhz, and if your min freq is higher than 245mhz, it will reset the min to 120mhz while screen is off and restore it upon screen awakening, and still scale accordingly to conservatives laws. So it spends most of its time at lower frequencies. The goal of this is to get the best battery life with decent performance. It will give the same performance as conservative right now, it will get tweaked over time.
13: Lagfree:
Lagfree is similar to ondemand. Main difference is it's optimization to become more battery friendly. Frequency is gracefully decreased and increased, unlike ondemand which jumps to 100% too often. Lagfree does not skip any frequency step while scaling up or down. Remember that if there's a requirement for sudden burst of power, lagfree can not satisfy that since it has to raise cpu through each higher frequency step from current. Some users report that video playback using lagfree stutters a little.
14: Smoothass:
The same as the Smartass “governor” But MUCH more aggressive & across the board this one has a better battery life that is about a third better than stock KERNEL
15: Brazilianwax:
Similar to smartassV2. More aggressive ramping, so more performance, less battery
16: SavagedZen:
Another smartassV2 based governor. Achieves good balance between performance & battery as compared to brazilianwax.
17: Lazy:
This governor from Ezekeel is basically an ondemand with an additional parameter min_time_state to specify the minimum time CPU stays on a frequency before scaling up/down. The Idea here is to eliminate any instabilities caused by fast frequency switching by ondemand. Lazy governor polls more often than ondemand, but changes frequency only after completing min_time_state on a step overriding sampling interval. Lazy also has a screenoff_maxfreq parameter which when enabled will cause the governor to always select the maximum frequency while the screen is off.
18: Lionheart:
Lionheart is a conservative-based governor which is based on samsung's update3 source.
The tunables (such as the thresholds and sampling rate) were changed so the governor behaves more like the performance one, at the cost of battery as the scaling is very aggressive.
19: LionheartX
LionheartX is based on Lionheart but has a few changes on the tunables and features a suspend profile based on Smartass governor.
20: Intellidemand:
Intellidemand aka Intelligent Ondemand from Faux is yet another governor that's based on ondemand. Unlike what some users believe, this governor is not the replacement for OC Daemon (Having different governors for sleep and awake). The original intellidemand behaves differently according to GPU usage. When GPU is really busy (gaming, maps, benchmarking, etc) intellidemand behaves like ondemand. When GPU is 'idling' (or moderately busy), intellidemand limits max frequency to a step depending on frequencies available in your device/kernel for saving battery. This is called browsing mode. We can see some 'traces' of interactive governor here. Frequency scale-up decision is made based on idling time of CPU. Lower idling time (<20%) causes CPU to scale-up from current frequency. Frequency scale-down happens at steps=5% of max frequency. (This parameter is tunable only in conservative, among the popular governors)
To sum up, this is an intelligent ondemand that enters browsing mode to limit max frequency when GPU is idling, and (exits browsing mode) behaves like ondemand when GPU is busy; to deliver performance for gaming and such. Intellidemand does not jump to highest frequency when screen is off.
21: Hotplug Governor:
The Hotplug governor performs very similarly to the OnDemand governor, with the added benefit of being more precise about how it steps down through the kernel's frequency table as the governor measures the user's CPU load. However, the Hotplug governor's defining feature is its ability to turn unused CPU cores off during periods of low CPU utilization. This is known as "hotplugging."
22: BadAss Governor:
Badass removes all of this "fast peaking" to the max frequency. On a typical system the cpu won't go above 918Mhz and therefore stay cool and will use less power. To trigger a frequency increase, the system must run a bit @ 918Mhz with high load, then the frequency is bumped to 1188Mhz. If that is still not enough the governor gives you full throttle. (this transition should not take longer than 1-2 seconds, depending on the load your system is experiencing)
Badass will also take the gpu load into consideration. If the gpu is moderately busy it will bypass the above check and clock the cpu with 1188Mhz. If the gpu is crushed under load, badass will lift the restrictions to the cpu.
23: Wheatley:
Building on the classic 'ondemand' governor is implemented Wheatley governor. The governor has two additional parameters:
target_residency - The minimum average residency in µs which is considered acceptable for a proper efficient usage of the C4 state. Default is 10000 = 10ms.
allowed_misses - The number sampling intervals in a row the average residency is allowed to be lower than target_residency before the governor reduces the frequency. This ensures that the governor is not too aggressive in scaling down the frequency and reduces it just because some background process was temporarily causing a larger number of wakeups. The default is 5.
Wheatley works as planned and does not hinder the proper C4 usage for task where the C4 can be used properly .
For internet browsing the time spend in C4 has increased by 10% points and the average residency has increased by about 1ms. I guess these differences are mostly due to the different browsing behaviour (I spend the last time more multi-tabbing). But at least we can say that Wheatley does not interfere with the proper use of the C4 state during 'light' tasks. For music playback with screen off the time spend in C4 is practically unchanged, however the average residency is reduced from around 30ms to around 18ms, but this is still more than acceptable.
So the results show that Wheatley works as intended and ensures that the C4 state is used whenever the task allows a proper efficient usage of the C4 state. For more demanding tasks which cause a large number of wakeups and prevent the efficient usage of the C4 state, the governor resorts to the next best power saving mechanism and scales down the frequency. So with the new highly-flexible Wheatley governor one can have the best of both worlds.
Obviously, this governor is only available on multi-core devices.
Credits goes to:
http://icrontic.com/discussion/95140...m-tuner-tegrak
http://forum.xda-developers.com/show....php?t=1369817
Thank you for the great information.
Cool its interesting to know all the features of the govs I used thx
Sent from my LG-P500 using xda premium
updated
Found this guide here -----> http://forum.xda-developers.com/showthread.php?t=1369817 . Thought I should share as it might help someone here. This guide was originally wriiten for SGS2 but I have Modded it for the EVO 3D. If you find something incorrect please let me know , I will continue to change it to make it fully EVO 3D compatible. Thank the original writer for this.
Most of us are flash maniacs, and we do it a lot. But after a kernel flash, we wonder:
Q1. "OK i have flashed this xyz kernel. What're all these governors? How do i know which one is the best for me? How do i tweak them to bias their characters towards Battery-life/Performance/Balance between the Two".
Q2. "What's the fuzz about these modules that comes with the kernel. How do i use them. Are they any good. Is it OK to neglect them?"
Q3. "What roles does an i/o scheduler play? How to choose a reliable i/o scheduler?"
Q4. "Can i have more control on CPU? More info and tweaks on dual core CPU, bus frequency, etc?"
Hope this thread could give you answers for all these questions. We're covering governors, modules, i/o schedulers, plus more. That should cover almost all the popular governors/modules/io schedulers! Many people seem to get lost in Kernel dev threads without getting answers about governors and such.
POST 1: KERNEL GOVERNORS
POST 2: GOVERNOR PARAMATERS
POST 3: I/O SCHEDULERS
POST 4: Q&A AND TWEAKS
1. GOVERNORS
I) MANUAL:
These are the 19 governors we're talking about.
1) Ondemand
2) Ondemandx
3) Conservative
4) Interactive
5) Interactivex
6) Lulzactive
7) Lulzactiveq
8) Smartass
9) SmartassV2
10) Intellidemand
11) Lazy
12) Lagfree
13) Lionheart
14) LionheartX
15) Brazilianwax
16) SavagedZen
17) Userspacce
18) Powersave
19) Performance
1) Ondemand:
Default governor in almost all stock kernels. One main goal of the ondemand governor is to switch to max frequency as soon as there is a CPU activity detected to ensure the responsiveness of the system. (You can change this behavior using smooth scaling parameters, refer Siyah tweaks at the end of 3rd post.) Effectively, it uses the CPU busy time as the answer to "how critical is performance right now" question. So Ondemand jumps to maximum frequency when CPU is busy and decreases the frequency gradually when CPU is less loaded/apporaching idle. Even though many of us consider this a reliable governor, it falls short on battery saving and performance on default settings. One potential reason for ondemand governor being not very power efficient is that the governor decide the next target frequency by instant requirement during sampling interval. The instant requirement can response quickly to workload change, but it does not usually reflect workload real CPU usage requirement in a small longer time and it possibly causes frequently change between highest and lowest frequency.
2) Ondemandx:
Basically an ondemand with suspend/wake profiles. This governor is supposed to be a battery friendly ondemand. When screen is off, max frequency is capped at 500 mhz. Even though ondemand is the default governor in many kernel and is considered safe/stable, the support for ondemand/ondemandX depends on CPU capability to do fast frequency switching which are very low latency frequency transitions. I have read somewhere that the performance of ondemand/ondemandx were significantly varying for different i/o schedulers. This is not true for most of the other governors. I personally feel ondemand/ondemandx goes best with SIO I/O scheduler.
3) Conservative:
A slower Ondemand which scales up slowly to save battery. The conservative governor is based on the ondemand governor. It functions like the Ondemand governor by dynamically adjusting frequencies based on processor utilization. However, the conservative governor increases and decreases CPU speed more gradually. Simply put, this governor increases the frequency step by step on CPU load and jumps to lowest frequency on CPU idle. Conservative governor aims to dynamically adjust the CPU frequency to current utilization, without jumping to max frequency. The sampling_down_factor value acts as a negative multiplier of sampling_rate to reduce the frequency that the scheduler samples the CPU utilization. For example, if sampling_rate equal to 20,000 and sampling_down_factor is 2, the governor samples the CPU utilization every 40,000 microseconds.
4) Interactive:
Can be considered a faster ondemand. So more snappier, less battery. Interactive is designed for latency-sensitive, interactive workloads. Instead of sampling at every interval like ondemand, it determines how to scale up when CPU comes out of idle. The governor has the following advantages: 1) More consistent ramping, because existing governors do their CPU load sampling in a workqueue context, but interactive governor does this in a timer context, which gives more consistent CPU load sampling. 2) Higher priority for CPU frequency increase, thus giving the remaining tasks the CPU performance benefit, unlike existing governors which schedule ramp-up work to occur after your performance starved tasks have completed. Interactive It's an intelligent Ondemand because of stability optimizations. Why??
Sampling the CPU load every X ms (like Ondemand) can lead to under-powering the CPU for X ms, leading to dropped frames, stuttering UI, etc. Instead of sampling the CPU at a specified rate, the interactive governor will check whether to scale the CPU frequency up soon after coming out of idle. When the CPU comes out of idle, a timer is configured to fire within 1-2 ticks. If the CPU is very busy between exiting idle and when the timer fires, then we assume the CPU is underpowered and ramp to max frequency.
5) Interactivex:
This is an Interactive governor with a wake profile. More battery friendly than interactive.
6) Lulzactive:
This new find from Tegrak is based on Interactive & Smartass governors and is one of the favorites.
Old Version: When workload is greater than or equal to 60%, the governor scales up CPU to next higher step. When workload is less than 60%, governor scales down CPU to next lower step. When screen is off, frequency is locked to global scaling minimum frequency.
New Version: Three more user configurable parameters: inc_cpu_load, pump_up_step, pump_down_step. Unlike older version, this one gives more control for the user. We can set the threshold at which governor decides to scale up/down. We can also set number of frequency steps to be skipped while polling up and down.
When workload greater than or equal to inc_cpu_load, governor scales CPU pump_up_step steps up. When workload is less than inc_cpu_load, governor scales CPU down pump_down_step steps down.
Example:
Consider
inc_cpu_load=70
pump_up_step=2
pump_down_step=1
If current frequency=200, Every up_sampling_time Us if cpu load >= 70%, cpu is scaled up 2 steps - to 800.
If current frequency =1200, Every down_sampling_time Us if cpu load < 70%, cpu is scaled down 1 step - to 1000.
7) Lulzactiveq:
Lulzactiveq is a modified lulzactive governor authored by XDA member robertobsc and is adapted in Siyah kernel for GS2 and GS3. Lulzactiveq aims to optimize the second version of luzactive from Tegrak by a) providing an extra parameter (dec_cpu_load) to make scaling down more sensible, and b) incorporating hotplug logic to the governor. Luzactiveq is the first ever interactive based governor with hotplugging logic inbuilt (atleast the first of its kind for the exynos platform). When CPU comes out of idle loop and it's time to make a scaling decision, if load >= inc_cpu_load CPU is scaled up (like original luzactiveq) and if load <dec_cpu_load, CPU is scaled down. This possibly eliminates the strict single cut-off frequency for luzactiveq to make CPU scaling decisions. Also, stand hotplug logic runs as a separate thread with the governor so that external hotplugging logic is not required to control hotplug in and out (turn On and Off) CPU cores in multi core devices like GS2 or GS3. Only a multi core aware governor makes real sense on muti-core devices. Lulzactiveq and pegasusq aims to do that.
8) Smartass:
Result of Erasmux rewriting the complete code of interactive governor. Main goal is to optimize battery life without comprising performance. Still, not as battery friendly as smartassV2 since screen-on minimum frequency is greater than frequencies used during screen-off. Smartass would jump up to highest frequency too often as well.
9) SmartassV2:
Version 2 of the original smartass governor from Erasmux. Another favorite for many a people. The governor aim for an "ideal frequency", and ramp up more aggressively towards this freq and less aggressive after. It uses different ideal frequencies for screen on and screen off, namely awake_ideal_freq and sleep_ideal_freq. This governor scales down CPU very fast (to hit sleep_ideal_freq soon) while screen is off and scales up rapidly to awake_ideal_freq (500 mhz for GS2 by default) when screen is on. There's no upper limit for frequency while screen is off (unlike Smartass). So the entire frequency range is available for the governor to use during screen-on and screen-off state. The motto of this governor is a balance between performance and battery.
10) Intellidemand:
Intellidemand aka Intelligent Ondemand from Faux is yet another governor that's based on ondemand. Unlike what some users believe, this governor is not the replacement for OC Daemon (Having different governors for sleep and awake). The original intellidemand behaves differently according to GPU usage. When GPU is really busy (gaming, maps, benchmarking, etc) intellidemand behaves like ondemand. When GPU is 'idling' (or moderately busy), intellidemand limits max frequency to a step depending on frequencies available in your device/kernel for saving battery. This is called browsing mode. We can see some 'traces' of interactive governor here. Frequency scale-up decision is made based on idling time of CPU. Lower idling time (<20%) causes CPU to scale-up from current frequency. Frequency scale-down happens at steps=5% of max frequency. (This parameter is tunable only in conservative, among the popular governors )
To sum up, this is an intelligent ondemand that enters browsing mode to limit max frequency when GPU is idling, and (exits browsing mode) behaves like ondemand when GPU is busy; to deliver performance for gaming and such. Intellidemand does not jump to highest frequency when screen is off.
11) Lazy:
This governor from Ezekeel is basically an ondemand with an additional parameter min_time_state to specify the minimum time CPU stays on a frequency before scaling up/down. The Idea here is to eliminate any instabilities caused by fast frequency switching by ondemand. Lazy governor polls more often than ondemand, but changes frequency only after completing min_time_state on a step overriding sampling interval. Lazy also has a screenoff_maxfreq parameter which when enabled will cause the governor to always select the maximum frequency while the screen is off.
12) Lagfree:
Lagfree is similar to ondemand. Main difference is it's optimization to become more battery friendly. Frequency is gracefully decreased and increased, unlike ondemand which jumps to 100% too often. Lagfree does not skip any frequency step while scaling up or down. Remember that if there's a requirement for sudden burst of power, lagfree can not satisfy that since it has to raise cpu through each higher frequency step from current. Some users report that video playback using lagfree stutters a little.
13) Lionheart:
Lionheart is a conservative-based governor which is based on samsung's update3 source. Tweaks comes from 1) Knzo 2) Morfic. The original idea comes from Netarchy. See here. The tunables (such as the thresholds and sampling rate) were changed so the governor behaves more like the performance one, at the cost of battery as the scaling is very aggressive.
To 'experience' Lionheart using conservative, try these tweaks:
sampling_rate:10000 or 20000 or 50000, whichever you feel is safer. (transition latency of the CPU is something below 10ms/10,000uS hence using 10,000 might not be safe).
up_threshold:60
down_threshold:30
freq_step:5
Lionheart goes well with deadline i/o scheduler. When it comes to smoothness (not considering battery drain), a tuned conservative delivers more as compared to a tuned ondemand.
14) LionheartX
LionheartX is based on Lionheart but has a few changes on the tunables and features a suspend profile based on Smartass governor.
15) Brazilianwax:
Similar to smartassV2. More aggressive ramping, so more performance, less battery.
16) SavagedZen:
Another smartassV2 based governor. Achieves good balance between performance & battery as compared to brazilianwax.
17) Userspace:
Instead of automatically determining frequencies, lets user set frequencies.
18) Powersave:
Locks max frequency to min frequency. Can not be used as a screen-on or even screen-off (if scaling min frequency is too low).
19) Performance:
Sets min frequency as max frequency. Use this while benchmarking!
So, Governors can be categorized into 3/4 on a high level:
1.a) Ondemand Based:
Works on "ramp-up on high load" principle. CPU busy-time is taken into consideration for scaling decisions. Members: Ondemand, OndemandX, Intellidemand, Lazy, Lagfree.
1.b) Conservative Based:
Members: Conservative, Lionheart, LionheartX
2) Interactive Based:
Works on "make scaling decision when CPU comes out of idle-loop" principle. Members: Interactive, InteractiveX, Lulzactive, Luzactiveq, Smartass, SmartassV2, Brazilianwax, SavagedZen.
3) Weird Category:
Members: Userspace, Powersave, Performance.
Governor tweaks in Post 2.
(First post extended here. )
2.GOVERNOR PARAMETERS
[Only Ondemand, Conservative, SmartassV2, Lulzactive and Interactive; being the most preferred governors.]
Different governors has different parameters. But it's easy to understand a governor. Ideally, a governor will have:-
1) Sampling Time/Rate measured in uS by which the polling function determines how often to poll and decide if frequency should be scaled-down or scaled-up. [Some governors will have different sampling time for scaling-up and scaling-down]
2) Thresholds measured in percentage. When CPU load reaches this point, governor scales up or scales down the CPU. [Most of the governors will have down-threshold and up-threshold, for which CPU is scaled down or up respectively.
There are various other parameters/factors too, but all are in someway related to these two parameters.
1.ONDEMAND
[ PARAMETERS ]
i) sampling_rate - Measured in uS , this is how often the kernel look at the CPU usage and make decisions on what to do about the frequency. Higher values means CPU polls less often. For lower frequencies, this could be considered an advantage since it might not jump to next frequency very often, but for higher frequencies, the scale-down time will be increased.
ii) up_threshold - Measured in percentage 1-100, When CPU load reaches this point, governor will scale CPU up. Higher value means less responsiveness and lower values corresponds to more responsiveness at the cost of battery.
iii) powersave_bias - Default value is 0. Setting a higher value will bias the governor towards lower frequency steps. Use this if you want CPU to spend less time on higher frequencies. A better alternative would be to underclock to a lower frequency than using powersave bias.
iv) sampling_down_factor - In the simplest form, sampling_down_factor determines how often CPU should stay at higher frequencies when truly busy. Default behavior is fast switching to lower frequencies (1). Having sampling_down_factor set to 1 makes no changes from existing behavior (for the non-modified ondemand), but having sampling_down_factor set to a value greater than 1 causes it to act as a multiplier for the scheduling interval for re-evaluating the load when the CPU is at its highest clock frequency (which is scaling_max_freq) due to high load. This improves performance by reducing the overhead of load evaluation and helping the CPU stay at its highest clock frequency when it is truly busy, rather than shifting back and forth in speed. This tunable has no effect on behavior at lower frequencies/lower CPU loads.
v) down_differential - This factor indirectly calculate the 'down-threshold' of Ondemand. After completing sampling-down-factor*sampling-rate at max frequency because of high load, governor samples the load again to calculate an estimate of the new target frequency in a way that the lowest frequency will be chosen that would not trigger up_threshold in the next sample. Because triggering up-threshold will again cause CPU to scale up to max frequency. During this choice down_differential is taken into account as a breathing room value. Target frequency is calculated as max_load_freq / (up_threshold - down_differential). The obtained value might be a non-existent value in the freq_table and CPU driver will round it off to a value in freq_table. max_load_freq is the theoretical frequency at which CPU can handle 100% workload. It is usually a value below scaling_max_freq. See this post by AndereiLux for more info.
2.LULZACTIVE
1. Initial Version:-
[ PARAMETERS ]
i) down_sampling_time - Sampling time to scale cpu down.
ii) up_sampling_time - Sampling time to scale cpu up.
2. Second Version:-
[ PARAMETERS ]
i) inc_cpu_load - In previous version, this was 'hard-coded' to 60. Now it's user-configurable. The frequency at which governor scales CPU up/down. Load < inc_cpu_load: cpu scaled down. Load >= inc_cpu_load: cpu scaled up
ii) pump_up_step - No of scale up steps when load >= inc_cpu_load
iii) pump_down_step - No of scale down steps when load < inc_cpu_load
iv) screen_off_min_step - Steps in frequency table to be used when screen-off. Example: If available freqs are 1600 1400 1200 1000 800 500 200 100 (L0 to L7) and screen_off_min_step=5 then 100,200 and 500 (L5 to L7) will be used during screen-off depending on the demand.
v) up_sample_time - same as initial version. (Allowed values 10,000 to 50,000)
vi) down_sample_time - same as older version. (Allowed values 10,000 to 100,000)
note: If you're lazy to use a script, use lulzactive app from market to tweak the governor. https://market.android.com/details?id=com.tegrak.lulzactive
3.SMARTASSV2
[ PARAMETERS ]
i) awake_ideal_freq - The frequency until which CPU is scaled up rapidly on screen-awake (from sleep). Thereafter, scaling up is less aggressive.
ii) sleep_ideal_freq - The frequency until which CPU is scaled down rapidly when screen is turned off. Thereafter, scaling down is less aggressive.
iii) up_rate_us - The minimum amount of time to spend at a frequency before we can ramp up. (Ignored below awake-ideal frequency since governor needs to rapidly scale up to awake_ideal_freq when below it)
iv) down_rate_us - The minimum amount of time to spend at a frequency before we can ramp down. (Ignored above sleep-ideal frequency since governor needs to rapidly scale down to sleep_ideal_freq when above it)
v) max_cpu_load - Same as up_threshold in other governors.
vi) min_cpu_load - Same as down_threshold in other governors.
vii) ramp_down_step - Frequency delta when ramping down below the ideal frequency. Zero disables and will calculate ramp down according to load heuristic. When above the ideal frequency we always ramp down to the ideal freq.
viii) ramp_up_step - Frequency when ramping up above the ideal frequency. Zero disables and causes to always jump straight to max frequency. When below the ideal frequency we always ramp up to the ideal freq.
ix) sleep_wakeup_freq - The frequency to set when waking up from sleep. When sleep_ideal_freq=0 this will have no effect.
4.CONSERVATIVE
[ PARAMETERS ]
i) down_threshold, ii) up_threshold, iii) sampling_down_factor, iv) sampling_rate - Refer above governors.
v) freq_step - Defines how much (as a percentage of the maximum CPU speed) the conservative governor will increase the CPU speed by each time the CPU load reaches the Up Threshold.
5.INTERACTIVE
[ PARAMETERS ]
i) hispeed_freq - Hi speed to bump to from lo speed when load burst. (Default value is scaling max freq)
ii) go_hispeed_load - Go to hi speed when CPU load at or above this value. (Similar to Up-Threshold in other governors)
iii) min_sample_time - The minimum amount of time to spend at a frequency before we can ramp down. (Sounds like Lazy governor?!)
iv) timer_rate - The sample rate of the timer used to increase frequency.
3. I/O SCHEDULERS
Q. "What purposes does an i/o scheduler serve?"
A.
Minimize hard disk seek latency.
Prioritize I/O requests from processes.
Allocate disk bandwidth for running processes.
Guarantee that certain requests will be served before a deadline.
So in the simplest of simplest form: Kernel controls the disk access using I/O Scheduler.
Q. "What goals every I/O scheduler tries to balance?"
A.
Fairness (let every process have its share of the access to disk)
Performance (try to serve requests close to current disk head position first, because seeking there is fastest)
Real-time (guarantee that a request is serviced in a given time)
Q. "Description, advantages, disadvantages of each I/O Scheduler?"
A.
1) Noop
Inserts all the incoming I/O requests to a First In First Out queue and implements request merging. Best used with storage devices that does not depend on mechanical movement to access data (yes, like our flash drives). Advantage here is that flash drives does not require reordering of multiple I/O requests unlike in normal hard drives.
Advantages:
Serves I/O requests with least number of cpu cycles. (Battery friendly?)
Best for flash drives since there is no seeking penalty.
Good throughput on db systems.
Disadvantages:
Reduction in number of cpu cycles used is proportional to drop in performance.
2) Deadline
Goal is to minimize I/O latency or starvation of a request. The same is achieved by round robin policy to be fair among multiple I/O requests. Five queues are aggressively used to reorder incoming requests.
Advantages:
Nearly a real time scheduler.
Excels in reducing latency of any given single I/O.
Best scheduler for database access and queries.
Bandwidth requirement of a process - what percentage of CPU it needs, is easily calculated.
Like noop, a good scheduler for solid state/flash drives.
Disadvantages:
When system is overloaded, set of processes that may miss deadline is largely unpredictable.
3) CFQ
Completely Fair Queuing scheduler maintains a scalable per-process I/O queue and attempts to distribute the available I/O bandwidth equally among all I/O requests. Each per-process queue contains synchronous requests from processes. Time slice allocated for each queue depends on the priority of the 'parent' process. V2 of CFQ has some fixes which solves process' i/o starvation and some small backward seeks in the hope of improving responsiveness.
Advantages:
Considered to deliver a balanced i/o performance.
Easiest to tune.
Excels on multiprocessor systems.
Best database system performance after deadline.
Disadvantages:
Some users report media scanning takes longest to complete using CFQ. This could be because of the property that since the bandwidth is equally distributed to all i/o operations during boot-up, media scanning is not given any special priority.
Jitter (worst-case-delay) exhibited can sometimes be high, because of the number of tasks competing for the disk.
4) BFQ
Instead of time slices allocation by CFQ, BFQ assigns budgets. Disk is granted to an active process until it's budget (number of sectors) expires. BFQ assigns high budgets to non-read tasks. Budget assigned to a process varies over time as a function of it's behavior.
Advantages:
Believed to be very good for usb data transfer rate.
Believed to be the best scheduler for HD video recording and video streaming. (because of less jitter as compared to CFQ and others)
Considered an accurate i/o scheduler.
Achieves about 30% more throughput than CFQ on most workloads.
Disadvantages:
Not the best scheduler for benchmarking.
Higher budget assigned to a process can affect interactivity and increased latency.
5) SIO
Simple I/O scheduler aims to keep minimum overhead to achieve low latency to serve I/O requests. No priority quesues concepts, but only basic merging. Sio is a mix between noop & deadline. No reordering or sorting of requests.
Advantages:
Simple, so reliable.
Minimized starvation of requests.
Disadvantages:
Slow random-read speeds on flash drives, compared to other schedulers.
Sequential-read speeds on flash drives also not so good.
6) V(R)
Unlike other schedulers, synchronous and asynchronous requests are not treated separately, instead a deadline is imposed for fairness. The next request to be served is based on it's distance from last request.
Advantages:
May be best for benchmarking because at the peak of it's 'form' VR performs best.
Disadvantages:
Performance fluctuation results in below-average performance at times.
Least reliable/most unstable.
7) Anticipatory
Based on two facts
i) Disk seeks are really slow.
ii) Write operations can happen whenever, but there is always some process waiting for read operation.
So anticipatory prioritize read operations over write. It anticipates synchronous read operations.
Advantages:
Read requests from processes are never starved.
As good as noop for read-performance on flash drives.
Disadvantages:
'Guess works' might not be always reliable.
Reduced write-performance on high performance disks.
Q. "Best I/O Scheduler?"
A.There is nothing called "best" i/o scheduler. Depending on your usage environment and tasks/apps been run, use different schedulers. That's the best i can suggest.
However, considering the overall performance, battery, reliability and low latency, it is believed that
SIO > Noop > Deadline > VR > BFQ > CFQ, given all schedulers are tweaked and the storage used is a flash device.
Q. "How do i change I/O schedulers?"
Voltage Control or No Frills from market or kernel tuner from pedja1.
Or init.d script
4. Q&A and TWEAKS
Q&A on parameters and factors that control the performance, throughput and battery-life delivered by dual-core CPU, and some CPU tweaks
Q. "What is the significance of bus frequency?"
A. Bus speed at its simplest form determines how fast the data should travel to and from memory. Memory throughput is directly proportional to bus frequency. In tasks that includes small amount of work on every element in a data sets, lower bus speed means longer the CPU has to wait for data to arrive from memory. Because, CPU spends only little time on each of these elements, and a slow bus cannot catch-up.
Advanced Micro-controller Bus Architecture (AMBA) is used as the on-chip bus in system-on-a-chip designs, like our device.
Q. "What is modifying bus frequency? How do I do it? Advantages?"
A. Stock behavior is dynamic bus frequency scaling, where in operating bus speed is dynamically calculated for each CPU frequency depending on the application/process’s requirement. We can modify this behavior by setting static bus frequency scaling, specifying at what bus speed should each CPU frequency operate.
Advantages of bus frequency modification: i) Saves battery by using low bus speeds on low frequencies and ii) Prevent overheating.
Q. "Our phone CPU has two cores. How are they utilized? Are the two cores ON all the time?What else can I do to improve phone performance and save battery?"
A. The stock behavior is asynchronous where depending on the load, the second core is turned on. If the load can be handled by a single core, the second core is turned off. This behavior can be controlled by using apps like system tuner or kernel tuner etc.
Using Kernel tuner from pedja1 in GSM section here-> http://forum.xda-developers.com/showthread.php?t=1719934
You can:
1.Fully Control the CPU and its settings. .
Single Core Mode (turn off second core in settings): Irrespective of the load, only first core is used always. This can lead to increased battery, but reduced performance.
Dual Core Mode: Irrespective of low loads, both the cores are always active. Increased performance, but reduced battery.
2.OC/UC the 2D and 3D GPU frequencies.
Overclocking GPU:This will boost gaming performance with some extra battery drain.
Underclocking GPU:This will save battery but performance will drop.
3.Enable/Disable Vsync
VSYNC ON: This will lock the fps to that of screen refresh rate.
VSYNC OFF: This will boost FPS but on some hardware it can distort the display.
4.Changing buttons backlight: Lowering this.can save you more battery
5.Fastcharge: By enabling this your phone will charge quickly as if it is connected to AC when connected to PC
6.Change IO Scheduler: Depending on this , your phones performance will vary. Check the IO SCHEDULAR post for more info.
7.Modify SD cache size
8.Toggle Swep2Wake
This will work on both CDMA & GSM EVO 3Ds
Q. "Like governors, is there a sampling rate/interval also at which the load on CPU is checked for crossing thresholds to turn second core ON?"
A. Yes there is. But it is set at kernel level in most kernels and can not be controlled at user level. higher sampling rate could cause core 2 to kick in less often and thus save a little battery.
Q. "Sometimes the device says 'low battery' and switches itself off. But when i turn it on, there's 30% left. Why?"
A. Some heavy load conditions such as quickly reaching max frequency on full load, etc will cause the battery voltage to time below 3.3V and this is wrongly interpreted by the battery as empty.
AGAIN..
Which governor has best overall battery life?
Bumping this thread to draw more attention to it. Thanks for modding it to fit our beloved EVO 3D, it was a great read during the night. Rock EVO, freaks!
Android CPU governors and schedulers explained in easy to understand language.
What is a governor?
A governor is a driver for the regulation of CPUFreq - CPU frequency. As the name suggests, we, the Governor of the decision, when at full capacity, the MaxFreq - will be achieved or how fast the minFreq - - maximum frequency is reached minimum frequency or center frequency. He decides when, how and how long the CPU and still responds battery saving is still soft and still works.
There are many types of governors. Some are for single-core processors and some designed for dual-core processors. In stock kernel, there are five governors and quasar kernel, there are a lot more.
1: OnDemand
2: OndemandX
3: Performance
4: Powersave
5: Conservative
6: Userspace
7: Min Max
8: Interactive
9: InteractiveX
10: Smartass
11: SmartassV2
12: Scary
13: Lagfree
14: Smoothass
15: Brazilianwax
16: SavagedZen
17: Lazy
18: Lionheart
19: LionheartX
20: Intellidemand
21: Hotplug
22: Wheatley
23: Lulzactive
24: AbyssPlug
25. BadAss
26. Ktoonservative
27. AssWax
28. Sleepy
29. Hyper
30: Pegasusq/Pegasusd
31: MSM DCVS
32: hotplugx
33: zen
1: OnDemand Governor:
This governor has a hair trigger for boosting clockspeed to the maximum speed set by the user. If the CPU load placed by the user abates, the OnDemand governor will slowly step back down through the kernel's frequency steppings until it settles at the lowest possible frequency, or the user executes another task to demand a ramp.
OnDemand has excellent interface fluidity because of its high-frequency bias, but it can also have a relatively negative effect on battery life versus other governors. OnDemand is commonly chosen by smartphone manufacturers because it is well-tested, reliable, and virtually guarantees the smoothest possible performance for the phone. This is so because users are vastly more likely to ***** about performance than they are the few hours of extra battery life another governor could have granted them.
This final fact is important to know before you read about the Interactive governor: OnDemand scales its clockspeed in a work queue context. In other words, once the task that triggered the clockspeed ramp is finished, OnDemand will attempt to move the clockspeed back to minimum. If the user executes another task that triggers OnDemand's ramp, the clockspeed will bounce from minimum to maximum. This can happen especially frequently if the user is multi-tasking. This, too, has negative implications for battery life.
2: OndemandX:
Basically an ondemand with suspend/wake profiles. This governor is supposed to be a battery friendly ondemand. When screen is off, max frequency is capped at 500 mhz. Even though ondemand is the default governor in many kernel and is considered safe/stable, the support for ondemand/ondemandX depends on CPU capability to do fast frequency switching which are very low latency frequency transitions. I have read somewhere that the performance of ondemand/ondemandx were significantly varying for different i/o schedulers. This is not true for most of the other governors. I personally feel ondemand/ondemandx goes best with SIO I/O scheduler.
3: Performance Governor:
This locks the phone's CPU at maximum frequency. While this may sound like an ugly idea, there is growing evidence to suggest that running a phone at its maximum frequency at all times will allow a faster race-to-idle. Race-to-idle is the process by which a phone completes a given task, such as syncing email, and returns the CPU to the extremely efficient low-power state. This still requires extensive testing, and a kernel that properly implements a given CPU's C-states (low power states).
4: Powersave Governor:
The opposite of the Performance governor, the Powersave governor locks the CPU frequency at the lowest frequency set by the user.
5:Conservative Governor:
This biases the phone to prefer the lowest possible clockspeed as often as possible. In other words, a larger and more persistent load must be placed on the CPU before the conservative governor will be prompted to raise the CPU clockspeed. Depending on how the developer has implemented this governor, and the minimum clockspeed chosen by the user, the conservative governor can introduce choppy performance. On the other hand, it can be good for battery life.
The Conservative Governor is also frequently described as a "slow OnDemand," if that helps to give you a more complete picture of its functionality.
6: Userspace Governor:
This governor, exceptionally rare for the world of mobile devices, allows any program executed by the user to set the CPU's operating frequency. This governor is more common amongst servers or desktop PCs where an application (like a power profile app) needs privileges to set the CPU clockspeed.
7: Min Max
well this governor makes use of only min & maximum frequency based on workload... no intermediate frequencies are used.
8: Interactive Governor:
Much like the OnDemand governor, the Interactive governor dynamically scales CPU clockspeed in response to the workload placed on the CPU by the user. This is where the similarities end. Interactive is significantly more responsive than OnDemand, because it's faster at scaling to maximum frequency.
Unlike OnDemand, which you'll recall scales clockspeed in the context of a work queue, Interactive scales the clockspeed over the course of a timer set arbitrarily by the kernel developer. In other words, if an application demands a ramp to maximum clockspeed (by placing 100% load on the CPU), a user can execute another task before the governor starts reducing CPU frequency. This can eliminate the frequency bouncing discussed in the OnDemand section. Because of this timer, Interactive is also better prepared to utilize intermediate clockspeeds that fall between the minimum and maximum CPU frequencies. This is another pro-battery life benefit of Interactive.
However, because Interactive is permitted to spend more time at maximum frequency than OnDemand (for device performance reasons), the battery-saving benefits discussed above are effectively negated. Long story short, Interactive offers better performance than OnDemand (some say the best performance of any governor) and negligibly different battery life.
Interactive also makes the assumption that a user turning the screen on will shortly be followed by the user interacting with some application on their device. Because of this, screen on triggers a ramp to maximum clockspeed, followed by the timer behavior described above.
9: InteractiveX Governor:
Created by kernel developer "Imoseyon," the InteractiveX governor is based heavily on the Interactive governor, enhanced with tuned timer parameters to better balance battery vs. performance. The InteractiveX governor's defining feature, however, is that it locks the CPU frequency to the user's lowest defined speed when the screen is off.
10: Smartass
Is based on the concept of the interactive governor.
I have always agreed that in theory the way interactive works – by taking over the idle loop – is very attractive. I have never managed to tweak it so it would behave decently in real life. Smartass is a complete rewrite of the code plus more. I think its a success. Performance is on par with the “old” minmax and I think smartass is a bit more responsive. Battery life is hard to quantify precisely but it does spend much more time at the lower frequencies.
Smartass will also cap the max frequency when sleeping to 352Mhz (or if your min frequency is higher than 352 – why?! – it will cap it to your min frequency). Lets take for example the 528/176 kernel, it will sleep at 352/176. No need for sleep profiles any more!"
11: SmartassV2:
Version 2 of the original smartass governor from Erasmux. Another favorite for many a people. The governor aim for an "ideal frequency", and ramp up more aggressively towards this freq and less aggressive after. It uses different ideal frequencies for screen on and screen off, namely awake_ideal_freq and sleep_ideal_freq. This governor scales down CPU very fast (to hit sleep_ideal_freq soon) while screen is off and scales up rapidly to awake_ideal_freq (500 mhz for GS2 by default) when screen is on. There's no upper limit for frequency while screen is off (unlike Smartass). So the entire frequency range is available for the governor to use during screen-on and screen-off state. The motto of this governor is a balance between performance and battery.
12: Scary
A new governor wrote based on conservative with some smartass features, it scales accordingly to conservatives laws. So it will start from the bottom, take a load sample, if it's above the upthreshold, ramp up only one speed at a time, and ramp down one at a time. It will automatically cap the off screen speeds to 245Mhz, and if your min freq is higher than 245mhz, it will reset the min to 120mhz while screen is off and restore it upon screen awakening, and still scale accordingly to conservatives laws. So it spends most of its time at lower frequencies. The goal of this is to get the best battery life with decent performance. It will give the same performance as conservative right now, it will get tweaked over time.
13: Lagfree:
Lagfree is similar to ondemand. Main difference is it's optimization to become more battery friendly. Frequency is gracefully decreased and increased, unlike ondemand which jumps to 100% too often. Lagfree does not skip any frequency step while scaling up or down. Remember that if there's a requirement for sudden burst of power, lagfree can not satisfy that since it has to raise cpu through each higher frequency step from current. Some users report that video playback using lagfree stutters a little.
14: Smoothass:
The same as the Smartass “governor” But MUCH more aggressive & across the board this one has a better battery life that is about a third better than stock KERNEL
15: Brazilianwax:
Similar to smartassV2. More aggressive ramping, so more performance, less battery
16: SavagedZen:
Another smartassV2 based governor. Achieves good balance between performance & battery as compared to brazilianwax.
17: Lazy:
This governor from Ezekeel is basically an ondemand with an additional parameter min_time_state to specify the minimum time CPU stays on a frequency before scaling up/down. The Idea here is to eliminate any instabilities caused by fast frequency switching by ondemand. Lazy governor polls more often than ondemand, but changes frequency only after completing min_time_state on a step overriding sampling interval. Lazy also has a screenoff_maxfreq parameter which when enabled will cause the governor to always select the maximum frequency while the screen is off.
18: Lionheart:
Lionheart is a conservative-based governor which is based on samsung's update3 source.
The tunables (such as the thresholds and sampling rate) were changed so the governor behaves more like the performance one, at the cost of battery as the scaling is very aggressive.
19: LionheartX
LionheartX is based on Lionheart but has a few changes on the tunables and features a suspend profile based on Smartass governor.
20: Intellidemand:
Intellidemand aka Intelligent Ondemand from Faux is yet another governor that's based on ondemand. Unlike what some users believe, this governor is not the replacement for OC Daemon (Having different governors for sleep and awake). The original intellidemand behaves differently according to GPU usage. When GPU is really busy (gaming, maps, benchmarking, etc) intellidemand behaves like ondemand. When GPU is 'idling' (or moderately busy), intellidemand limits max frequency to a step depending on frequencies available in your device/kernel for saving battery. This is called browsing mode. We can see some 'traces' of interactive governor here. Frequency scale-up decision is made based on idling time of CPU. Lower idling time (<20%) causes CPU to scale-up from current frequency. Frequency scale-down happens at steps=5% of max frequency. (This parameter is tunable only in conservative, among the popular governors)
To sum up, this is an intelligent ondemand that enters browsing mode to limit max frequency when GPU is idling, and (exits browsing mode) behaves like ondemand when GPU is busy; to deliver performance for gaming and such. Intellidemand does not jump to highest frequency when screen is off.
21: Hotplug Governor:
The “hotplug” governor scales CPU frequency based on load, similar to “ondemand”. It scales up to the highest frequency when “up_threshold” is crossed and scales down one frequency at a time when “down_threshold” is crossed. Unlike those governors, target frequencies are determined by directly accessing the CPUfreq frequency table, instead of taking some percentage of maximum available frequency.
The key difference in the “hotplug” governor is that it will disable auxillary CPUs when the system is very idle, and enable them again once the system becomes busy. This is achieved by averaging load over multiple sampling periods; if CPUs were online or offlined based on a single sampling period then thrashing will occur.
Sysfs entries exist for “hotplug_in_sampling_periods” and for “hotplug_out_sampling_periods” which determine how many consecutive periods get averaged to determine if auxillery CPUs should be onlined or offlined. Defaults are 5 periods and 20 periods respectively. Otherwise the standard sysfs entries you might find for “ondemand” and “conservative” governors are there.
Obviously, this governor is only available on multi-core devices.
22: Wheatley
in short words this govenor is build on “ondemand” but increases the C4 state time of the CPU and doing so trying to save juice.
23: Basically interactive governor with added smartass bits and variable (as opposed to fixed amout) frequency scaling, based on currently occuring cpu loads. Has, like smartass, a sleep profile built-in. See link for details on exact scaling.
24: Abyssplug governor is a modified hotplug governor.
25. BadAss Governor:
Badass removes all of this "fast peaking" to the max frequency. On a typical system the cpu won't go above 918Mhz and therefore stay cool and will use less power. To trigger a frequency increase, the system must run a bit @ 918Mhz with high load, then the frequency is bumped to 1188Mhz. If that is still not enough the governor gives you full throttle. (this transition should not take longer than 1-2 seconds, depending on the load your system is experiencing)
Badass will also take the gpu load into consideration. If the gpu is moderately busy it will bypass the above check and clock the cpu with 1188Mhz. If the gpu is crushed under load, badass will lift the restrictions to the cpu.
26, Ktonnservative
Ondemand scales to the highest frequency as soon as a load occurs. Conservative scales upward based on the frequency step variable which means for the most part will scale through every frequency to achieve the target load thresholds. What this practically means is ondemand is prone to wasting power on unneeded clock cycles. Ondemand also features something called a down differential, this variable determines how long the governor will remain at the given frequency before scaling down. Conservative does not have this, but instead relies on having a down threshold which insures that as soon as the load drops below a given variable it scales down as fast as the sampling rate allows. The result to this is a governor which attempts to keep the load level tolerable and save you battery! Now ! Ktoonservative Is that but in addition contains a hotpluging variable which determines when the second core comes online. The governor shuts the core off when it returns to the second lowest frequency thus giving us a handle on the second performance factor in our CPUs behavior. While by default conservative is a poor performer it can be made to perform comparably to even performance governor. Here are some settings to discuss and start with. They are slightly less battery friendly under a load but very very well performing.
27. AssWax
So far, all I have found about this Governor is that it belongs in the interactive family. I'll update this when I find more
28. Sleepy
The Sleepy (formerly known as Solo) is an attempt to strike a balance between performance and battery power to create. It is based on the getweakten Ondemand of Arighi and is optimized for the SGS2. It may include imoseyon's Ondemandx with some tweaks Down_sampling and other features that set by the user through the sysfs of "echo" call. Sleepy is the behavior of Ondemandx when he is in action, very similar.
29. Hyper
The Hyper (formerly known as kenobi) is an aggressive smart and smooth, optimized for SGS2 getweakt and, based on the Ondemand, which was getweakt of Arighi and was equipped with several features of Ondemandx suspend imoseyon. (Added by sysfs, the settings suspend_freq and suspend Imoseyon's code) is the behavior of the hyper Ondemand if he is in action, very similar. He also has the Arighi's fast_start deep_sleep and detection features. In addition, the maximum frequency is in suspend mode 500Mhz.
30: Pegasusq/Pegasusd
The Pegasus-q / d is a multi-core based on the Ondemand governor and governor with integrated hot-plugging.
Ongoing processes in the queue, we know that multiple processes can run simultaneously on. These processes are active in an array, which is a field called "Run Queue" queue that is ongoing, with their priority values arranged (priority will be used by the task scheduler, which then decides which process to run next).
To ensure that each process has its fair share of resources, each running for a certain period and will eventually stop and then again placed in the queue until it is your turn again. If a program is terminated, so that others can run the program with the highest priority in the current queue is executed.
31: MSM DCVS
A very efficient and wide range of Dynamic Clock and
Voltage Scaling (DCVS) which addresses usage models from
active standby to mid and high level processing requirements.
A Krait CPU can smoothly scale from low power, low
leakage mode to blazingly fast performance.
Believe it's a governor that is mfg'd by qualcomm to utilize new on chip features.
MSM is the prefix for the SOC (MSM8960) and DCVS is Dynamic Clock and Voltage Scaling. Makes sense, MSM-DCVS
32: hotplugx
It 'a Hotplug modified and optimized for the suspension in off-screen
33: zen
It's an FCFS (First come, first serve) based algorithm. It's not strictly FIFO. It does not do any sorting. It uses deadlines for fairness, and treats synchronous requests with priority over asynchronous ones. Other than that, pretty much the same as no-op.
What is a scheduler?
In a multitasking operating system, there must be an instance, the processes that want to run, CPU time and allocates it "goes to sleep" after the allotted time (timeslice) again. This instance is called the scheduler, such as opening and closing applications. that is, how fast they are open and how long they are kept in RAM.
I / O scheduler can have many purposes like:
To minimize time searching on the hard disk
Set priorities for specific process requests
To regulate a particular portion of the bandwidth of the data carrier to each running process
To guarantee certain process requests within a certain time
Which scheduler are available?
CFQ
Deadline
VR
Simple
Noop
Anticipatory
BFQ
Sio
Anticipatory:
Two important things here are indicative of that event:
- Looking on the flash drive is very slow from Equip
- Write operations while at any time are processed, however, be read operations preferred, ie, this scheduler returns the read operations a higher priority than the write operations.
Benefits:
- Requests of read accesses are never treated secondarily, that has equally good reading performance on flash drives like the noop
Disadvantages:
- Requests from process operations are not always available
- Reduced write performance on high-performance hard drives
CFQ:
The CFQ - Completely Fair Queuing - similar to the Dead Line maintains a scalable continuous Prozess-I/O-Warteschlange, ie the available I / O bandwidth tried fairly and evenly to all I / O requests to distribute. He created a statistics between blocks and processes. With these statistics it can "guess" when the next block is requested by what process, ie each process queue contains requests of synchronous processes, which in turn is dependent upon the priority of the original process. There is a V2 and the CFQ has some fixes, such as were the I / O request, hunger, and some small search backward integrated to improve the responsiveness.
Benefits:
- Has the goal of a balanced I / O performance to deliver
- The easiest way to set
- Excellent on multiprocessor systems
- Best performance of the database after the deadline
Disadvantages:
- Some reported user that the media scanning would take this very very long time and this by the very fair and even distribution of bandwidth on the I / O operations during the boot process is conditioned with the media scanning is not necessarily the highest should have priority
- Jitter (worst case delay) can sometimes be very high because the number of competing with each other process tasks
Deadline:
This scheduler has the goal of reducing I / O wait time of a process of inquiry. This is done using the block numbers of the data on the drive. This also blocks an outlying block numbers are processed, each request receives a maximum delivery time. This is in addition to the Governor BFQ very popular and in many well known kernels, such as the Nexus S Netarchy. He was indeed better than the BFQ, but compared to the VR he will be weaker.
Benefits:
- Is nearly a real-time scheduler.
- Characterized by reducing the waiting time of each process from - best scheduler for database access and queries.
- Bandwidth requirements of a process, eg what percentage does a CPU is easy to calculate.
- As the Governor-noop ideal for flash drives
Disadvantages:
- If the system is overloaded, can go a lost set of processes, and is not as easy to predict
SIO:
It aims to achieve with minimal effort at a low latency I / O requests. Not a priority to put in queue, instead simply merge the requests. This scheduler is a mix between the noop and deadline. With him there is no conversion or sorting of requests.
Benefits:
- It is simple and stable. - Minimized Starvations (starvation) for inquiries
Disadvantages:
- Slow random write speeds on flash drives as opposed to other schedulers. - Sequential read speeds on flash drives, not as good
Noop:
The noop scheduler is the simplest of them. He is best suited for storage devices that are not subject to mechanical movements, such as our flash drives in our SGSII's to use to access the data. The advantage is that flash drives do not require rearrangement of the I / O requests, unlike normal hard drives. ie the data that come first are written first. He's basically not a real scheduler, as it leaves the scheduling of the hardware.
Benefits:
- Adds all incoming I / O requests in a first-come-who-first-served queue and implements requests with the fewest number of CPU cycles, so also battery friendly
- Is suitable for flash drives because there is no search errors
- Good data throughput on db systems
Disadvantages:
- Reducing the number of CPU cycles corresponds to a simultaneous decline in performance einhergehendem
VR:
Unlike other scheduling software, synchronous and asynchronous requests are not handled separately, but it will impose a fair and balanced within this deadline requests, that the next request to be served is a function of distance from the last request. The VR is a very good scheduler with elements of the deadline scheduler. He will probably be the best for MTD Android devices. He is the one who can make the most of the benchmark points, but he is also an unstable schedulers, because his performance falter. Sometimes they fluctuate below the average, sometimes it fluctuates above the average, but if above, then he is the best.
Benefits:
- Is the best scheduler for benchmarks
Disadvantages:
- Performance variability can lead to different results
- Very often unstable or unzverlässig
Simple:
As the name suggests, it is more of a simple or simple scheduler. Especially suitable for EMMC devices. He is reliable, maybe not as good as the VR, when this time has a good day, but he is despite all this very performance-based and does his best. At the moment it is the default scheduler in quasar kernel.
Advantages: - not known
Cons: - not known
BFQ:
Instead requests divided into time segments as the CFQ has, on the BFQ budget. The flash drive will be granted an active process until it has exhausted its budget (number of sectors on the flash drive). The awards BFQ high budget does not read tasks.
Benefits:
- Has a very good USB data transfer rate.
- Be the best scheduler for playback of HD video recording and video streaming (due to less jitter than CFQ Scheduler, and others)
- Regarded as a very precise working Scheduler
- Delivers 30% more throughput than CFQ
Disadvantages:
- Not the best scheduler for benchmarks - higher budgets that were allocated to a process that can affect the interactivity and bring with it increased latency.
How can I change the governor and scheduler?
There are two ways to change the governor and schedulers, as well as the settings for the Governorn. Either manually, in which you use a file manager like Root Explorer and then knows how to / sys / devices / system and then change the files to his wishes, provided you what you're doing, or via a graphical interface or by phone as SetCPU Voltage Control. These are the most prominent apps when it comes to adjusting the governor and / or scheduler.
- SetCPU are, besides the possibility of the clock speed of the CPU, setting profiles in certain situations, only to change the way the governor. The scheduler can not change it.
- Voltage control can alter both the governor and the scheduler, but has no way to adjust behavior profiles. While you can set various overclocking, Governor and scheduler profiles manually, but nothing more. Nevertheless, I prefer the VC, since it is simple and gives me the opportunity to change the scheduler.
If you find any other IMPORTANT governors being left out , just leave a comment.
Credit goes to jpkelly05 , stempox and XDA
reserved
Good Job!!
Informative thread!!
Must be made a sticky I guess.
Good Job man really helps a lot in deciding which governor i should use! but i think u forgot smaartassH3
Ace King 34 said:
Good Job!!
Informative thread!!
Must be made a sticky I guess.
Click to expand...
Click to collapse
yeah i guess :highfive: :good:
Blackbox421 said:
Good Job man really helps a lot in deciding which governor i should use! but i think u forgot smaartassH3
Click to expand...
Click to collapse
i thought its not used that much . . . anyways ill add it soon
CPU Governors, Hotplug drivers and GPU governors Explained Part 1 (Updated 23/12/16)
------------------------------------------------------------------------------------------------------------------
Official XDA thread Of The Contributer: http://forum.xda-developers.com/member.php?u=5811506
Edited By ShivaY: http://forum.xda-developers.com/member.php?u=6704044
Guide Part 2 Link: http://forum.xda-developers.com/lenovo-a6000/how-to/cpu-governors-hotplug-drivers-gpu-t3528766
Guide Part 3 Link :http://forum.xda-developers.com/lenovo-a6000/how-to/cpu-governors-hotplug-drivers-gpu-t3528771
Guide Part 4 Link : http://forum.xda-developers.com/lenovo-a6000/how-to/cpu-governors-hotplug-drivers-gpu-t3528772
Here I've gathered some info for newcomers to the Android world.I've tried to keep it relatively simple. So if you want more info Comment Below
Recommended apps for manipulating kernel values:
1. Kernel Adiutor (Free to change governor and tune variables)
2. Kernel Adiutor-Mod (Free to change governor and tune variables)
3. Compatible kernel managers (e.g Stweaks, Synapse, UKM, etc.)
This pages includes:
-----------------------------
Descriptions
governors
Hotplug drivers
CPU governors
Governor types
Recommendations
Graphs
Tunables
What is a CPU governor?
-----------------------------------
A CPU governor in Android controls how the CPU raises and lowers its frequency in response to the demands the user is placing on their device. Governors are especially important in smartphones and tablets because they have a large impact on the apparent fluidity of the interface and the battery life of the device over a charge.
NOTE: You cannot change your CPU governor unless your phone is rooted and you have a ROM or app that lets you make a change. Also, different kernels (the intermediary software between your phone's hardware and the operating system) offer different sets of governors.
Available CPU governors:
---------------------------------
1. OnDemand
2. OnDemandX
3. Performance
4. Powersave
5. Conservative
6. Userspace
7. Min Max
8. Interactive
9. InteractiveX
10. Smartass
11. SmartassV2
12. Scary
13. Lagfree
14. Smoothass
15. Brazilianwax
16. SavageZen
17. Lazy
18. Lionheart
19. LionheartX
20. Intellidemand
21. Hotplug
22. Badass
23. Wheatley
24. Lulzactive
25. PegasusQ\PegasusD
26. HotplugX
27. Abyssplug
28. MSM DCVS
29. Intelliactive
30. Adaptive
31. Nightmare
32. ZZmoove
33. Sleepy
34. Hyper
35. SmartassH3
36. SLP
37. NeoX
38. ZZmanX
39. OndemandPlus
40. Dynamic Interactive (DynInteractive)
41. Smartmax
42. Ktoonservative\KtoonservativeQ
43. Performance may cry (PMC)
44. Dance Dance
45. AbyssPlugv2
46. IntelliMM
47. InteractivePro
48. Slim
49. Ondemand EPS
50. Smartmax EPS
51. Uberdemand
52. Yankactive
53. Impulse
54. Bacon
55. Optimax
56. Preservative
57. Touchdemand
58. ElementalX
59. Bioshock
60. Blu_active
61. Umbrella_core
62. ConservativeX
63. Hyrdxq
64. DevilQ
65. Yankasusq
66. Darkness
67. Alucard
68. Hellsactive
69. Ragingmolasses
70. Virtuous
71. Sakuractive
72. InteractiveX v2
73. Alessa
74. GallimaufryX
75. AggressiveX
76. Tripndroid
77. Wrexy
78. Xperience
79. Stockdemand
80. Zeneractive
81. InteractiveB
82. Aggressive
83. IntellidemandV2
84. Boostactive
85. Wave
86. Barry-Allen
87. Arteractive
88. Precognition (PrecoGOV)
89. Mythx_plug
90. PegasusQPlus
91. Yankdemand
92. HyperX
93. Despair
94. Electroactive
95. Electrodemand
96. Lionfish
97. Interextrem
98. Cafactive
99. Lightning
100. ThunderX
101. sched-DVFS
102. Intel
103. Frankenstein
104. Cyan
105. TheSSJactive
106. Chill
107. sprdemand
108. Kraken
109. Ironactive
Things to look out for in a CPU governor:
--------------------------------------------------------
There are many CPU governors available on android, but there are some important things people should look out for before selecting their new governor:
Speed
---------
- Some governors are faster than others and some are slower. This all depends on if the governor is biased towards performance or towards battery life. Balanced governors tend to be on the middle-ground providing optimal speed when required.
Battery life
----------------
- Generally, if the governor is biased towards performance, it will drain your battery faster. If the governor is biased towards battery life, the battery should drain slower. If the governor is balanced, then it will try to provide optimal performance while trying to be battery friendly when possible. This also depends on usage patterns and other factors such as background applications or wakelocks (when your CPU is on even though your screen is off).
Stability
-------------
- The stability of a governor is dependent on a number of factors like how well the developer has implemented the governor and can vary between different devices. One governor may work well for a specific platform but may not work well on others. It is also important to look out if the governor is a Work-In-Progress (WIP) where bugs may be encountered during usage.
Smoothness
-----------------
- Not to be confused with speed, a governor can be fast but it doesn't also mean it is smooth. Some governors implement features such as touch boost to help improve the "responsiveness" when touch events are registered. Others may choose to ramp down the frequency over a timer to attempt to provide CPU power for successive events.
Descriptions:
-------------------------
------------------------------
1: OnDemand:
---------------------
Ondemand is one of the original and oldest governors available on the linux kernel. When the load placed on your CPU reaches the set threshold, the governor will quickly ramp up to the maximum CPU frequency. It has excellent fluidity because of this high-frequency bias, but it can also have a relatively negative effect on battery life versus other governors. OnDemand was commonly chosen by smartphone manufacturers in the past because it is well-tested and reliable, but it is outdated now and is being replaced by Google's Interactive governor.
2: OndemandX:
---------------------
Basically an ondemand with suspend/wake profiles. No further optimization was done to Ondemand to keep it close to source as possible.
3: Performance:
-----------------------
The performance governor locks the phone's CPU at maximum frequency.
4: Powersave:
--------------------
The opposite of the Performance governor, the Powersave governor locks the CPU frequency at the lowest frequency set by the user.
5: Conservative:
------------------------------
This governor biases the phone to prefer the lowest possible clockspeed as often as possible. In other words, a larger and more persistent load must be placed on the CPU before the conservative governor will be prompted to raise the CPU clockspeed. Depending on how the developer has implemented this governor, and the minimum clockspeed chosen by the user, the conservative governor can introduce choppy performance. On the other hand, it can be good for battery life.
The Conservative Governor is also frequently described as a "slow OnDemand". The original and unmodified conservative is slow and inefficient. Newer and modified versions of conservative (from some kernels) are much more responsive and are better all around for almost any use.
6: Userspace:
--------------------
This governor, exceptionally rare for the world of mobile devices, allows any program executed by the user to set the CPU's operating frequency. This governor is more common amongst servers or desktop PCs where an application (like a power profile app) needs privileges to set the CPU clockspeed.
7: Min Max
-------------------
Min Max is a governor that makes use of only min & maximum frequency based on workload. no intermediate frequencies are used!
8: Interactive:
---------------------
Interactive scales the clockspeed over the course of a timer set by the kernel developer (or user). In other words, if an application demands a ramp to maximum clockspeed (by placing 100% load on the CPU), a user can execute another task before the governor starts reducing CPU frequency. Because of this timer, Interactive is also better prepared to utilize intermediate clockspeeds that fall between the minimum and maximum CPU frequencies. It is significantly more responsive than OnDemand, because it's faster at scaling to maximum frequency.
Interactive also makes the assumption that a user turning the screen on will shortly be followed by the user interacting with some application on their device. Because of this, screen on triggers a ramp to maximum clockspeed, followed by the timer behavior described above.
Interactive is the default governor of choice for today's smartphone and tablet manufacturers.
9: InteractiveX:
------------------------
Created by kernel developer "Imoseyon," the InteractiveX governor is based heavily on the Interactive governor, enhanced with tuned timer parameters to better balance battery vs. performance. The InteractiveX governor's defining feature, however, is that it locks the CPU frequency to the user's lowest defined speed when the screen is off.
10: Smartass
-----------------
Based on interactive, performance is on par with the �old� minmax and smartass is a bit more responsive. Battery life is hard to quantify precisely but it does spend much more time at the lower frequencies.
Smartass will also cap the max frequency when sleeping to 352Mhz (or if your min frequency is higher than 352 it will cap it to your min frequency).
This governor will slowly ramp down frequency when the screen is off and it could also let the frequency go to low making your phone unusable (if min frequency is not checked).
11: SmartassV2:
-------------------
Version 2 of the original smartass governor from Erasmux. The governor aim for an "ideal frequency", and ramp up more aggressively towards this freq and less aggressive after. It uses different ideal frequencies for screen on and screen off, namely awake_ideal_freq and sleep_ideal_freq. This governor scales down CPU very fast (to hit sleep_ideal_freq soon) while screen is off and scales up rapidly to awake_ideal_freq when screen is on. There's no upper limit for frequency while screen is off (unlike Smartass). So the entire frequency range is available for the governor to use during screen-on and screen-off state. The motto of this governor is a balance between performance and battery.
12: Scary
-------------
A new governor wrote based on conservative with some smartass features, it scales accordingly to conservatives laws. So it will start from the bottom, take a load sample, if it's above the up threshold, ramp up only one speed at a time, and ramp down one at a time. It will automatically cap the off screen speeds to whatever the kernel developer sets it too and will still scale accordingly to conservatives laws. So it spends most of its time at lower frequencies. The goal of this is to get the best battery life with decent performance.
13: Lagfree:
---------------
Lagfree is similar to ondemand. Main difference is it's optimization to become more battery friendly. Frequency is gracefully decreased and increased, unlike ondemand which jumps to 100% too often. Lagfree does not skip any frequency step while scaling up or down. Remember that if there's a requirement for sudden burst of power, lagfree can not satisfy that since it has to raise cpu through each higher frequency step from current. Some users report that video playback using lagfree stutters a little. Depending on the implementation, lagfree can also be performance oriented at the cost of battery life.
14: Smoothass:
----------------------
The same as the Smartass �governor� But MUCH more aggressive & across the board.
15: Brazilianwax:
------------------------
Similar to smartassV2. More aggressive ramping, so more performance, less battery
16: SavagedZen:
-----------------------
Another smartassV2 based governor. Achieves good balance between performance & battery as compared to brazilianwax.
17: Lazy:
-----------
This governor from Ezekeel is basically an ondemand with an additional parameter min_time_state to specify the minimum time CPU stays on a frequency before scaling up/down. The Idea here is to eliminate any instabilities caused by fast frequency switching by ondemand. Lazy governor polls more often than ondemand, but changes frequency only after completing min_time_state on a step overriding sampling interval. Lazy also has a screenoff_maxfreq parameter which when enabled will cause the governor to always select the maximum frequency while the screen is off.
18: Lionheart:
---------------------
Lionheart is a conservative-based governor which is based on samsung's update3 source.
The tunables (such as the thresholds and sampling rate) were changed so the governor behaves more like the performance one, at the cost of battery as the scaling is very aggressive.
19: LionheartX
-----------------------
LionheartX is based on Lionheart but has a few changes on the tunables and features a suspend profile based on Smartass governor.
20: Intellidemand:
--------------------------
Intellidemand aka Intelligent Ondemand from Faux is yet another governor that's based on ondemand. The original intellidemand behaves differently according to GPU usage. When GPU is really busy (gaming, maps, benchmarking, etc) intellidemand behaves like ondemand. When GPU is 'idling' (or moderately busy), intellidemand limits max frequency to a step depending on frequencies available in your device/kernel for saving battery. This is called browsing mode.
To sum up, this is an intelligent ondemand that enters browsing mode to limit max frequency when GPU is idling, and (exits browsing mode) by behaving like ondemand when GPU is busy; to deliver performance for gaming and such. Intellidemand does not jump to highest frequency when screen is off. Faux no longer recommends intellidemand and believes that intellidemand users should switch to intelliactive for better optimizations and performance.
21: Hotplug:
---------------------
The Hotplug governor performs very similarly to the OnDemand governor, with the added benefit of being more precise about how it steps down through the kernel's frequency table as the governor measures the user's CPU load. However, the Hotplug governor's defining feature is its ability to turn unused CPU cores off during periods of low CPU utilization. This is known as "hotplugging."
22: BadAss:
-----------------
Badass removes all of this "fast peaking" to the max frequency. To trigger a frequency increase, the system must run a bit with high load, then the frequency is bumped. If that is still not enough the governor gives you full throttle. (this transition should not take longer than 1-2 seconds, depending on the load your system is experiencing)
Badass will also take the gpu load into consideration. If the gpu is moderately busy it will bypass the above check and clock the cpu to max frequency. If the gpu is crushed under load, badass will lift the restrictions to the cpu.
23: Wheatley:
--------------------
This governor is build on �ondemand� but increases the C4 (the sleep state) state time of the CPU and doing so trying to save juice. So the results show that Wheatley works as intended and ensures that the C4 state is used whenever the task allows a proper efficient usage of the C4 state. For more demanding tasks which cause a large number of wakeups and prevent the efficient usage of the C4 state, the governor resorts to the next best power saving mechanism and scales down the frequency. So with the new highly-flexible Wheatley governor one can have the best of both worlds. Obviously, this governor is only available on multi-core devices.
Wheatley is a more performance orientated governor as it scales more aggressively than ondemand and sticks with higher frequencies.
24:Lulzactive\LulzactiveQ:
--------------------------------------
It's based on Interactive & Smartass governors.
Old Version: When workload is greater than or equal to 60%, the governor scales up CPU to next higher step. When workload is less than 60%, governor scales down CPU to next lower step. When screen is off, frequency is locked to global scaling minimum frequency.
New Version: Three more user configurable parameters: inc_cpu_load, pump_up_step, pump_down_step. Unlike older version, this one gives more control for the user. We can set the threshold at which governor decides to scale up/down. We can also set number of frequency steps to be skipped while polling up and down.
When workload greater than or equal to inc_cpu_load, governor scales CPU pump_up_step steps up. When workload is less than inc_cpu_load, governor scales CPU down pump_down_step steps down.
25: Pegasusq/Pegasusd
---------------------------------
The Pegasusq / d is a multi-core based on the Ondemand governor and governor with integrated hot-plugging. It is quite stable and has the same battery life as ondemand. Ongoing processes in the queue, we know that multiple processes can run simultaneously on. These processes are active in an array, which is a field called "Run Queue" queue that is ongoing, with their priority values ??arranged (priority will be used by the task scheduler, which then decides which process to run next).
To ensure that each process has its fair share of resources, each will run for a certain period and will eventually stop and then again placed in the queue until it is your turn again. If a program is terminated, so that others can run the program with the highest priority in the current queue is executed.
26: Hotplugx
--------------------
It's a modified version of Hotplug and optimized for the suspension in off-screen
27: AbyssPlug
-----------------
It's a Governor derived from hotplug, it works the same way, but with the changes in savings for more battery life.
28: MSM DCVS
----------------------
A very efficient and wide range of Dynamic Clock and Voltage Scaling (DCVS) which addresses usage models from active standby to mid and high level processing requirements. It makes the phone's CPU smoothly scale from low power, from low leakage mode to blazingly fast performance.Only to be used by Qualcomm CPUs.
MSM is the prefix for the SOC (MSM8960) and DCVS is Dynamic Clock and Voltage Scaling. Makes sense, MSM-DCVS
Guide Part 2 Link: http://forum.xda-developers.com/lenovo-a6000/how-to/cpu-governors-hotplug-drivers-gpu-t3528766
Guide Part 3 Link :http://forum.xda-developers.com/lenovo-a6000/how-to/cpu-governors-hotplug-drivers-gpu-t3528771
Guide Part 4 Link : http://forum.xda-developers.com/lenovo-a6000/how-to/cpu-governors-hotplug-drivers-gpu-t3528772
Please Press Thanks Button If It Helped . It Will Encourage Me to Work More For You Guys
THANK YOU:good:
CPU Governors, Hotplug drivers and GPU governors Explained Part 3 (Updated 30/12/16)
--------------------------------------------------------------------------------------------------------------------------------------------
Official XDA thread Of The Contributer: http://forum.xda-developers.com/member.php?u=5811506
Edited By ShivaY: http://forum.xda-developers.com/member.php?u=6704044
Guide Part 1 Link: http://forum.xda-developers.com/lenovo-a6000/how-to/cpu-governors-hotplug-drivers-gpu-t3528762
Guide Part 2 Link: http://forum.xda-developers.com/lenovo-a6000/how-to/cpu-governors-hotplug-drivers-gpu-t3528766
Guide Part 4 Link : http://forum.xda-developers.com/lenovo-a6000/how-to/cpu-governors-hotplug-drivers-gpu-t3528772
Here I've gathered some info for newcomers to the Android world.I've tried to keep it relatively simple. So if you want more info Comment Below
Recommended apps for manipulating kernel values:
1. Kernel Adiutor (Free to change governor and tune variables)
2. Kernel Adiutor-Mod (Free to change governor and tune variables)
3. Compatible kernel managers (e.g Stweaks, Synapse, UKM, etc.)
Hotplug drivers:
------------------------
mpdecision: Qualcomm's default hotplugging driver. One of the most widely used hotplug drivers in all android devices.
msm_hotplug: Great battery life, a custom qualcomm based hotplugging driver by myflux. It is a popular choice for many users.
intelliplug: Great balance between battery life and performance. It is also a popular hotplug driver from faux123.
Alucard: A great hotplugging driver by Alucard. It is known to be very battery friendly on devices.
Kt Auto Hotplug: A great hotplug driver by Ktoonsez. Pretty much a smarter mpdecision that has been optimized for quad-core devices.
Mako Hotplug: A new popular hotplugging driver found in Francokernel. This is a highly configurable driver that can be configured to use dual core for light-loads and quad-core for heavy loads.
Zen Decision: ZEN only onlines all cores when screen is on, it also takes thermal events into account and wont online any core back, if you're under 15% battery, or currently have a thermal event because of heat. So in the end it isn't a "real" hotplug driver, because it doesnt have any code for active hot plugging in it. That means you can't change its behavior.
Bricked Hotplug: Conservative hotplug driver by @showp1984. It is based on mpdecision but has been optimized for better balance between battery life and performance.
msm_sleeper: The main feature with this hotplug is that you can customize the screen off frequency. Two cores are always on, the third and fourth are independent and come online if needed. By default, if the load is over 80 for 400ms another core comes online. The third and/or fourth cores stay online as long as the load demands it or for a minimum of one second. While the screen is off, it goes down to a single core. Created by flar2.
Autosmp: A highly-efficient hotplug driver by @mrg666, works in-sync with the CPU governor to enable off-line cpu cores when the the CPU frequency reaches a high threshold and still more compute power is needed. Therefore, touch boost bloat is removed.
Thunderplug: A matured load-based hotplug driver with many tunables written from ground up by varun.chitre15. This hotplug is optimized for octa-core devices and also has support for 64bit CPUs.
Blu_plug: Dynamic hotplug from eng.stk's shamu kernel with screenoff battery saving.
cpuquiet: A hotplug driver by NVidia and ported to Snapdragon by maxwen. Originally made for NVidia tegra SOCs. It has a set of governors which keep the CPU running at optimal frequencies for battery and performance.
Fast hotplug: A hotplug driver from pec0ra's abricot kernel. It aims to be as lightweight as possible while also being highly customizable. However, it is still a WIP as it is known to have some stability issues.
Hima hotplug: An optimized hotplug driver based on intelliplug for big.LITTLE architecture. Found on chadouming's HTC One (M9) kernel, it takes advantage of the big and LITTLE CPU cores in order to provide 'butter smooth' performance.
State Helper: A hotplug driver by @neobuddy89 designed with the Nexus 6 in mind. It is highly configurable giving the user control over what CPUs to online based on what battery threshold levels have been set. Another feature that sets state helper apart from other hotplug methods is that it respects the thermal driver.
ZZmoove native hotplug: The hotplugging logic found in the ZZmoove governor. This isn't a standalone hotplug driver that can be used with other governors, the hotplugging is done by the governor which was common on older devices like the Samsung Galaxy S3. Native hotplugging may offer better stability and the governor should perform better in battery life and performance (your experience may vary) because it was designed for this specific governor.
Custom kernels may have their own hotplugging drivers but they are usually based on these ones.
Battery life:
mpdecision
Mako Hotplug
Intelliplug
Alucard
For performance:
mpdecision
For balanced:
Bricked Hotplug
Mako Hotplug
Intelliplug
mpdecision
GPU governors
-----------------------
Simple: An open-source alternative to Qualcomm's closed-sourced governors. Developed by Faux123, it is highly customisable which will allow more fine-grained control over how the GPU scales up and down.
simple_ondemand: As the name implies, it is a simpler version of the CPU governor ondemand. simple_ondemand will ramp up the frequency when a load is detected. It has a good balance between performance and battery savings.
msm-adreno-tz: The default GPU governor used by Qualcomm for their adreno GPUs. It is based on the ondemand governor but is biased towards performance, therefore it should give better performance in games but less battery life.
Performance: As the name suggests, this keeps your GPU running at the max frequency. This is a governor if you want the best possible experience in games but you don't care about your battery life.
Powersave: Like the CPU governor, this keeps your GPU running at the lowest possible frequency. Best battery life, extreme lag in games.
Adreno Idler: It is an idling algorithm, an efficient workaround for msm-adreno-tz's overheads. Main goal is to lower the power consumptions while maintaining high-performance. Since msm-adreno-tz tends to *not* use the lowest frequency even on idle, Adreno idler replaces msm-adreno-tz's algorithm when it comes to calculating idle frequency(mostly by ondemand's method). The higher frequencies are not touched with this algorithm, so high-demanding games will (most likely) not suffer from worsened performance.
Userspace: This governor basically allows the user is able to set a desired frequency for the GPU to run at.
cpubw_hwmon: A hardware monitor based governor that attempts to determine bandwidth (BW) needed by CPU and other hardware. Because it samples bandwidth using polling intervals, it has been made to be biased towards performance to compensate for the possible slower response times during heavy loads.
MSM Cpufreq: The MSM CPUfreq governor determines the CPU to DDR bandwidth vote based on the current CPU frequency of all the active CPUs. In other words, this governor scales based on CPU usage which could mean more performance.
Governor types:
----------------------
All governors are coded to behave on certain principles which can affect the performance, battery life, stability of your device. I won't be updating this guide often because there is simply too many governors.
1) Ondemand Based:
Works on "ramp-up on high load" principle. CPU busy-time is taken into consideration for scaling decisions. Members: Ondemand, OndemandX, Intellidemand, Lazy, Lagfree, PegasusQ, HYPER, Wheatley, Hotplug, HotplugX, AbyssPlug, AbyssPlugv2, Nightmare, Sleepy.
2) Conservative Based:
Works by biasing the phone to prefer the lowest possible clockspeed as often as possible. Members: Conservative, Lionheart, LionheartX
3) Interactive Based:
Works on "make scaling decision when CPU comes out of idle-loop" principle. Members: Interactive, InteractiveX, Intelliactive, Lulzactive, Luzactiveq, Smartass, SmartassV2, SmartassH3, Brazilianwax, SavagedZen, Dyninteractive, Interactive Pro
4) Unique Category:
These do not fall into any other category above and/or possess unique attributes. Members: Userspace, Powersave, Performance, Min Max, ZZmove, MSM DCVS, IntelliMM
5) Hybrid Category:
These have a mix of two (or more) CPU governor behaviors. Members: Smartmax, Dancedance, Performance May Cry(PMC), Ktoonservative, KtoonservativeQ
Recommendations:
-----------------------------
For performance:
Interactive/InteractiveX
Intelliactive
Performance
ElementalX
HYPER
Lionheart/LionheartX
Blu_active
For battery life:
Ondemand
Conservative
Perfomance may cry (PMC)
Powersave
Smartmax
Intellimm
Alucard
For balanced battery life and performance:
Interactive/InteractiveX
Intelliactive
Ondemand/Ondemand
ElementalX
Yankactive/YanksusQ
PegasusQ
HYPER
Impulse
ZZMoove
For gaming:
Interactive/InteractiveX
Intelliactive
Performance
Lionheart/LionheartX
PegasusQ
ElementalX
Ondemand/OndemandX
HYPER
Individual-core CPU governor selection
Some kernels will allow you to set a governor on a per-core basis. This can introduce a wider range of configurations which can alter the scaling of specific part of the CPU. While there is no definite guidelines on how to achieve optimal settings, here are some configurations you can do:
All cores running the same governor:
This will give the best stability and the CPU will behave as expected. This is the stock default on all devices.
All cores running different governors:
You should probably avoid this because it can cause stabilities and can significantly affect the performance and battery life of your CPU. Most kernel developers may not even provide support because there are too many combinations to choose from and because of the risks associated with this setup.
big.LITTLE cores running two different governors:
Similar to the previous setup, this could cause instabilities on your device and could affect how well your CPU performs. It is better just to use the same governor across all cores but there have been some setups like this.
CPU governor tunables
--------------------------------
NOTE: If you don't have some of these tunables, you might have an older version of the governor/hotplug driver and/or the kernel maintainer has made modifications to it.
1. ONDEMAND
[ PARAMETERS ]
Quote:
i) sampling_rate - Measured in uS , this is how often the kernel look at the CPU usage and make decisions on what to do about the frequency. Higher values means CPU polls less often. For lower frequencies, this could be considered an advantage since it might not jump to next frequency very often, but for higher frequencies, the scale-down time will be increased.
ii) up_threshold - defines what the average CPU usage between the samplings of 'sampling_rate' needs to be for the kernel to make a decision on whether it should increase the frequency. For example when it is set to its default value of '95' it means that between the checking intervals the CPU needs to be on average more than 95% in use to then
decide that the CPU frequency needs to be increased.
iii) powersave_bias - Default value is 0. Setting a higher value will bias the governor towards lower frequency steps. Use this if you want CPU to spend less time on higher frequencies. A better alternative would be to underclock to a lower frequency than using powersave bias.
iv) sampling_down_factor - Determines how often CPU should stay at higher frequencies when truly busy. Default behavior is fast switching to lower frequencies (1). Having sampling_down_factor set to 1 makes no changes from existing behavior (for the non-modified ondemand), but having sampling_down_factor set to a value greater than 1 causes it to act as a multiplier for the scheduling interval for re-evaluating the load when the CPU is at its highest clock frequency (which is scaling_max_freq) due to high load. T
v) down_differential - Indirectly calculates the 'down-threshold' of Ondemand. After completing sampling-down-factor*sampling-rate at max frequency because of high load, governor samples the load again to calculate an estimate of the new target frequency in a way that the lowest frequency will be chosen that would not trigger up_threshold in the next sample. Because triggering up-threshold will again cause CPU to scale up to max frequency. During this choice down_differential is taken into account as a breathing room value. Target frequency is calculated as max_load_freq / (up_threshold - down_differential).
vi) freq_step - Whenever up-scaling logic is triggered the governor instructs the CPU to raise its frequency by freq_step percentage of max allowed frequency. (max policy * (freq step / 100)). Ex: max policy is 1600 and freq step 21%, it will scale 1600 * 21% = 336.
vii) ignore_nice_load - this parameter takes a value of '0' or '1'. When set to '0' (its default), all processes are counted towards the 'cpu utilisation' value. When set to '1', the processes that are run with a 'nice' value will not count (and thus be ignored) in the overall usage calculation. This is useful if you are running a CPU intensive calculation on your laptop that you do not care how long it takes to complete as you can 'nice' it and prevent it from taking part in the deciding process of whether to increase your CPU frequency.
viii) sampling_rate_min -
The sampling rate is limited by the HW transition latency:
transition_latency * 100
Or by kernel restrictions:
If CONFIG_NO_HZ is set, the limit is 10ms fixed.
If CONFIG_NO_HZ is not set or nohz=off boot parameter is used, the
limits depend on the CONFIG_HZ option:
HZ=1000: min=20000us (20ms)
HZ=250: min=80000us (80ms)
HZ=100: min=200000us (200ms)
The highest value of kernel and HW latency restrictions is shown and
used as the minimum sampling rate.
2. LULZACTIVE/LULZACTIVEQ
1. Initial Version:-
[ PARAMETERS ]
Quote:
i) down_sampling_time - Sampling time to scale cpu down.
ii) up_sampling_time - Sampling time to scale cpu up.
2. Second Version (LulzactiveQ):-
[ PARAMETERS ]
Quote:
i) inc_cpu_load - In previous version, this was 'hard-coded' to 60. Now it's user-configurable. The frequency at which governor scales CPU up/down. Load < inc_cpu_load: cpu scaled down. Load >= inc_cpu_load: cpu scaled up
ii) pump_up_step - No of scale up steps when load >= inc_cpu_load
iii) pump_down_step - No of scale down steps when load < inc_cpu_load
iv) screen_off_min_step - Steps in frequency table to be used when screen-off. Example: If available freqs are 1600 1400 1200 1000 800 500 200 100 (L0 to L7) and screen_off_min_step=5 then 100,200 and 500 (L5 to L7) will be used during screen-off depending on the demand.
v) up_sample_time - same as initial version. (Allowed values 10,000 to 50,000)
vi) down_sample_time - same as older version. (Allowed values 10,000 to 100,000)
3. SMARTASSV2
[ PARAMETERS ]
Quote:
i) awake_ideal_freq - The frequency until which CPU is scaled up rapidly on screen-awake (from sleep). Thereafter, scaling up is less aggressive.
ii) sleep_ideal_freq - The frequency until which CPU is scaled down rapidly when screen is turned off. Thereafter, scaling down is less aggressive.
iii) up_rate_us - The minimum amount of time to spend at a frequency before we can ramp up. (Ignored below awake-ideal frequency since governor needs to rapidly scale up to awake_ideal_freq when below it)
iv) down_rate_us - The minimum amount of time to spend at a frequency before we can ramp down. (Ignored above sleep-ideal frequency since governor needs to rapidly scale down to sleep_ideal_freq when above it)
v) max_cpu_load - Same as up_threshold in other governors.
vi) min_cpu_load - Same as down_threshold in other governors.
vii) ramp_down_step - Frequency delta when ramping down below the ideal frequency. Zero disables and will calculate ramp down according to load heuristic. When above the ideal frequency we always ramp down to the ideal freq.
viii) ramp_up_step - Frequency when ramping up above the ideal frequency. Zero disables and causes to always jump straight to max frequency. When below the ideal frequency we always ramp up to the ideal freq.
ix) sleep_wakeup_freq - The frequency to set when waking up from sleep. When sleep_ideal_freq=0 this will have no effect.
4. CONSERVATIVE
[ PARAMETERS ]
Quote:
Ondemand and conservative have some tunables in common, but with a few extras:
i) freq_step - this describes what percentage steps the cpu freq should be increased and decreased smoothly by. By default the cpu frequency will increase in 5% chunks of your maximum cpu frequency. You can change this value to anywhere between 0 and 100 where '0' will effectively lock your CPU at a speed regardless of its load whilst '100' will, in theory, make
it behave identically to the "ondemand" governor.
ii) down_threshold - same as the 'up_threshold' found for the "ondemand" governor but for the opposite direction. For example when set to its default value of '20' it means that if the CPU usage needs to be below 20% between samples to have the frequency decreased.
5. INTERACTIVE
1. Generic Version
[ PARAMETERS ]
Quote:
i) hispeed_freq - An intermediate "hi speed" at which to initially ramp when CPU load hits the value specified in go_hispeed_load. If load stays high for the amount of time specified in above_hispeed_delay, then speed may be bumped higher. Default is the maximum speed allowed by the policy at governor initialization time.
ii) go_hispeed_load - The CPU load at which to ramp to hispeed_freq. Default is 99%.
iii) min_sample_time - The minimum amount of time to spend at the current frequency before ramping down. Default is 80000 uS.
iv) timer_rate - Sample rate for reevaluating CPU load when the CPU is not idle. A deferrable timer is used, such that the CPU will not be woken from idle to service this timer until something else needs to run. (The maximum time to allow deferring this timer when not running at
minimum speed is configurable via timer_slack.) Default is 20000 uS.
v) target_loads - CPU load values used to adjust speed to influence the current CPU load toward that value. In general, the lower the target load, the more often the governor will raise CPU speeds to bring load below the target. The format is a single target load, optionally followed by pairs of CPU speeds and CPU loads to target at or above those speeds. Colons can be used between the speeds and associated target loads for readability. For example:
85 1000000:90 1700000:99
targets CPU load 85% below speed 1GHz, 90% at or above 1GHz, until 1.7GHz and above, at which load 99% is targeted. If speeds are specified these must appear in ascending order. Higher target load values are typically specified for higher speeds, that is, target load values also usually appear in an ascending order. The default is target load 90% for all speeds.
vi) above_highspeed_delay - When speed is at or above hispeed_freq, wait for this long before raising speed in response to continued high load. The format is a single delay value, optionally followed by pairs of CPU speeds and the delay to use at or above those speeds. Colons can be used between the speeds and associated delays for readability. For example:
80000 1300000:200000 1500000:40000
uses delay 80000 uS until CPU speed 1.3 GHz, at which speed delay 200000 uS is used until speed 1.5 GHz, at which speed (and above) delay 40000 uS is used. If speeds are specified these must appear in ascending order. Default is 20000 uS.
vii) timer_slack - Maximum additional time to defer handling the governor sampling timer beyond timer_rate when running at speeds above the minimum. For platforms that consume additional power at idle when CPUs are running at speeds greater than minimum, this places an upper bound on how long the timer will be deferred prior to re-evaluating load and dropping speed. For example, if timer_rate is 20000uS and timer_slack is 10000uS then timers will be deferred for up to 30msec when not at lowest speed. A value of -1 means defer timers
indefinitely at all speeds. Default is 80000 uS.
viii) boost - If non-zero, immediately boost speed of all CPUs to at least hispeed_freq until zero is written to this attribute. If zero, allow CPU speeds to drop below hispeed_freq according to load as usual. Default is zero.
ix) boostpulse - On each write, immediately boost speed of all CPUs to hispeed_freq for at least the period of time specified by boostpulse_duration, after which speeds are allowed to drop below hispeed_freq according to load as usual.
x) boostpulse_duration - Length of time to hold CPU speed at hispeed_freq on a write to boostpulse, before allowing speed to drop according to load as usual. Default is 80000 uS.
2. Qualcomm Version/Intelliactive/IntelliMM
[ PARAMETERS ]
Quote:
Has some tunables in common with the generic version but with a few extras:
i) Sync_freq Feature - This feature will cause a CPU frequency to stay above a particular
value sync_freq) if certain conditions (determined by the two nodes
up_threshold_any_cpu_freq and up_threshold_any_cpu_load) are satisfied
ii) Sync_freq - Only when both of the above conditions are satisfied will the CPU not drop
below this frequency value. The higher this value, the higher the frequency to jump will
be when the above conditions are satisfied.
iii) Up_threshold_any_cpu_freq - If the maximum frequency across all the CPUs is higher
than or equal to this frequency value, do not let the current CPU fall below sync_freq.
The higher this value, the fewer the chances to go to sync_freq.
iv) Up_threshold_any_cpu_load - If the maximum load across all the CPUs is higher than
or equal to this load value, do not let the current CPU fall below sync_freq. The higher
this value, the fewer the chances to go to sync_freq.
v) up_threshold_multi_core - When the up_threshold_multi_core is crossed, the cpu is ramped up to optimal_freq.
vi) optimal_freq - When more than one CPU is online and if up_threshold_multi_core has exceeded, the governor will ramp up the CPU to this frequency. This value should be less than your device's max CPU frequency.
6. Wheatley
[ PARAMETERS ]
Quote:
target_residency - The minimum average residency in �s which is considered acceptable for a proper efficient usage of the C4 state. Default is 10000 = 10ms.
allowed_misses - The number sampling intervals in a row the average residency is allowed to be lower than target_residency before the governor reduces the frequency. This ensures that the governor is not too aggressive in scaling down the frequency and reduces it just because some background process was temporarily causing a larger number of wakeups. The default is 5.
7. Darkness/Nightmare
[ PARAMETERS ]
Quote:
cpu_up_rate - No of samples to evaluate load to scale CPU frequency up. Increasing this value will increase the time spent on a frequency.
cpu_down_rate - No of samples to evaluate load to scale CPU frequency down. Increasing this value will increase the time spent on a frequency
inc_cpu_load_at_min_freq - This threshold is used as up threshold while sampling at frequencies is less than freq_for_responsiveness.
inc_cpu_load - The frequency at which governor scales CPU up.
dec_cpu_load - The frequency at which governor scales CPU down.
Guide Part 1 Link: http://forum.xda-developers.com/lenovo-a6000/how-to/cpu-governors-hotplug-drivers-gpu-t3528762
Guide Part 2 Link: http://forum.xda-developers.com/lenovo-a6000/how-to/cpu-governors-hotplug-drivers-gpu-t3528766
Guide Part 4 Link : http://forum.xda-developers.com/lenovo-a6000/how-to/cpu-governors-hotplug-drivers-gpu-t3528772
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Hi, how to set default GPU governor in device config file?