Root KERNELS For Dummies

[3VOcrack]

Can someone do a detail description on kernel governors?

 

[ocnbrze]

Can someone do a detail description on kernel governors?

CPU Scaling Governors
CPU governors control exactly how the CPU scales between your "max" and "min" set frequencies. Most kernels have "ondemand" and "performance." The availability
ondemand - Available in most kernels, and the default governor in most kernels. When the CPU load reaches a certain point (see "up threshold" in Advanced Settings), ondemand will rapidly scale the CPU up to meet demand, then gradually scale the CPU down when it isn't needed.
conservative - Available in some kernels. It is similar to the ondemand governor, but will scale the CPU up more gradually to better fit demand. Conservative provides a less responsive experience than ondemand, but can save battery.
performance - Available in most kernels. It will keep the CPU running at the "max" set value at all times. This is a bit more efficient than simply setting "max" and "min" to the same value and using ondemand because the system will not waste resources scanning for the CPU load. This governor is recommended for stable benchmarking.
powersave - Available in some kernels. It will keep the CPU running at the "min" set value at all times.
userspace- A method for controlling the CPU speed that isn't currently used by SetCPU. For best results, do not use the userspace governor.

this was taken from the http://androidforums.com/evo-4g-all-things-root/210253-setcpu-guide.html

now i know that it does not include some of the new governors like interactive x or the smartass v2 governor, but i think you should get a better understanding of what they do.

 

[Xicor]

Hey guys.
So I downloaded and flashed sense 3.5 as my Rom lastnight before bed. I wake up and skim over it quick to see if i like it abd i love it but one thing I took notice was man it drains my battery like heck!!!! It dropped from 98% to 77% within not even 7 mins!! Ugh help. Please what could cause this? The kernal. Idk which kernal is good for 3.5 and which are bad. I'm new to this kernal thing sorry guys plx help thank you

 

[ocnbrze]

Hey guys.
So I downloaded and flashed sense 3.5 as my Rom lastnight before bed. I wake up and skim over it quick to see if i like it abd i love it but one thing I took notice was man it drains my battery like heck!!!! It dropped from 98% to 77% within not even 7 mins!! Ugh help. Please what could cause this? The kernal. Idk which kernal is good for 3.5 and which are bad. I'm new to this kernal thing sorry guys plx help thank you

ok so all of the gingerbread sense kernels are good for sense 3.5. they should all work. now which one is good for your phone is hard to say. every kernel reacts differently on different phones. really the only way to find out is to make a nandroid backup and start flashing them. always give the kernel a few days to settle in before deciding to move on to the next one. to give you a starting place, i would try the aggressive freedom and then work your way down the list. also i would use setcpu as well and try the smartass or interactive x governors.

so read the op for this thread and
http://androidforums.com/evo-4g-all-things-root/210253-setcpu-guide.html

 

[txtoddtattoo]

I would just like to know one thing. I have V6 Supercharger v0.9 running. Do I need to stop and unsupercharge before flashing a new kernel???

 

[ocnbrze]

I would just like to know one thing. I have V6 Supercharger v0.9 running. Do I need to stop and unsupercharge before flashing a new kernel???

the supercharger script works on optimizing memory management. it has nothing to do with kernels. so just wipe dalvik cache and cache and flash your kernel of choice.

 

[frenchy714]

the supercharger script works on optimizing memory management. it has nothing to do with kernels. so just wipe dalvik cache and cache and flash your kernel of choice.

+1

 

[Palmetto Fellow]

Is the Kernel saved with a NAND? I ask because I was going to experiment with some kernels, and wanted to know the best way to get back to the stock kernel.

Once I get my MikG the way I want, I am going to NAND backup and then try tiamat. If I want to go back to the stock kernel, can I just do a NAND restore instead of flashing the stock kernel?

 

[ocnbrze]

Is the Kernel saved with a NAND? I ask because I was going to experiment with some kernels, and wanted to know the best way to get back to the stock kernel.

Once I get my MikG the way I want, I am going to NAND backup and then try tiamat. If I want to go back to the stock kernel, can I just do a NAND restore instead of flashing the stock kernel?

yes, pretty much everything is backed up in nandroids. the only thing that can't be backed up is your radios (baseband, pri, and nv). so you should always make a nandroid backup when flashing kernels.

 

[frenchy714]

yes, pretty much everything is backed up in nandroids. the only thing that can't be backed up is your radios (baseband, pri, and nv). so you should always make a nandroid backup when flashing kernels.

+1 on making nands

 

[andygu3]

Is the Kernel saved with a NAND? I ask because I was going to experiment with some kernels, and wanted to know the best way to get back to the stock kernel.

Once I get my MikG the way I want, I am going to NAND backup and then try tiamat. If I want to go back to the stock kernel, can I just do a NAND restore instead of flashing the stock kernel?

DO NOT USE tiamat with a sense rom. This kernel is for AOSP roms only

 

[nick1313]

Is the Kernel saved with a NAND? I ask because I was going to experiment with some kernels, and wanted to know the best way to get back to the stock kernel.

Once I get my MikG the way I want, I am going to NAND backup and then try tiamat. If I want to go back to the stock kernel, can I just do a NAND restore instead of flashing the stock kernel?

Couple ways you can get the stock kernel back.

1) Nand restore like you said.
2) Reflash rom over the top of your current setup by only wiping cache/dalvik
***This method will get rid of any themes/mods you did but keep all your data
3) Flash the stock kernel by wiping cache/dalvik

 

[frenchy714]

Is the Kernel saved with a NAND? I ask because I was going to experiment with some kernels, and wanted to know the best way to get back to the stock kernel.

Once I get my MikG the way I want, I am going to NAND backup and then try tiamat. If I want to go back to the stock kernel, can I just do a NAND restore instead of flashing the stock kernel?

You can find the stock sense GB kernel here.

 

[vailpass]

I just flashed my first kernel, chopsuey 9.1 universal, to go with MikG3.0. Anybody running JuiceDefender along with a custome kernel? Does it do any good?

 

[frenchy714]

I just flashed my first kernel, chopsuey 9.1 universal, to go with MikG3.0. Anybody running JuiceDefender along with a custome kernel? Does it do any good?

IMO Juice Defender tends to do more bad than good. Toggling data on/off, etc., you can do manually. Using SetCPU in conjunction w/ a custom kernel will help tremendously as well.

 

[ocnbrze]

+1 to setcpu and not using juice defender. i never used it before, never had the need.

here is a great guide on it:
http://androidforums.com/evo-4g-all-things-root/210253-setcpu-guide.html

 

[vailpass]

IMO Juice Defender tends to do more bad than good. Toggling data on/off, etc., you can do manually. Using SetCPU in conjunction w/ a custom kernel will help tremendously as well.

thanks!

 

[vailpass]

+1 to setcpu and not using juice defender. i never used it before, never had the need.

here is a great guide on it:
http://androidforums.com/evo-4g-all-things-root/210253-setcpu-guide.html

Thanks ocnbrze.
Question: since I flashed chop suey the green light at the top of my phone flashes. Ever heard of this? I no likey.

 

[ocnbrze]

Thanks ocnbrze.
Question: since I flashed chop suey the green light at the top of my phone flashes. Ever heard of this? I no likey.

actually no i have not. i have not used chopsuey since it came out. my phone never really liked it very much. i do not see anything in the changelog about it. what rom are you on?and when does it come on?

 

[youdoofus]

have you wiped the cache and dalvik? i know thats quite the "when in doubt, wipe...." type of answer, but youd be surprised how often that works. Or it could be some apk that the rom comes with throwing a notification thats not in the notif bar... Alternatively, you could try reflashing the rom to see if that corrects it. In any event, none of the aforementioned fixes take a ton of time, nor are detrimental to your OS in any way. Hope that helps ya out homie

 

[vailpass]

+1 to setcpu and not using juice defender. i never used it before, never had the need.

here is a great guide on it:
http://androidforums.com/evo-4g-all-things-root/210253-setcpu-guide.html

So I'm sure I'm getting the right SetCPU app: is it the SetCPU for Root Users by Michael Huang for $1.99?

 

[nick1313]

So I'm sure I'm getting the right SetCPU app: is it the SetCPU for Root Users by Michael Huang for $1.99?

Yup..but if you are an xda member, I think you can get it for free.

ps. I got the paid one to support the dev, though. Up to you

 

[frenchy714]

SetCPU is something we all use (for the most part) in the root community. When speaking about over/underclocking, SetCPU is the standard. *Can* you get it free, yes you can, BUT, we need to be more supportive of these Devs that devote their time and energy for us, for very little...nothing most of the time.

 

[vailpass]

SetCPU is something we all use (for the most part) in the root community. When speaking about over/underclocking, SetCPU is the standard. *Can* you get it free, yes you can, BUT, we need to be more supportive of these Devs that devote their time and energy for us, for very little...nothing most of the time.

Because you paid for the breakfast, I'm gonna tip. Normally I wouldn't.

 

[NaterTots]

I wanted to bring this over here for the Kernels for Dummies Guide.
A great write-up on the different governors.


Thanks to HipKat for bringing this into the Evo forums on XDA.
Thanks to deedii for posting this in another forum:

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




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 bitch 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."

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


Link for Wheatley description
http://forum.xda-developers.com/showpost.php?p=21864389&postcount=75

Link for Lulzactive description
http://tegrak2x.blogspot.com/2011/11/lulzactive-governor-v2.html