Develop Bugs

[DEV][KERNEL] Tegra3 power management notes and tricks

This thread contains findings on how to view and set kernel parameters related to power management. Although there is no kernel source for One X, some information can be obtained from Transformer Prime kernel sources (also a Tegra 3 device), and from the device itself via sysfs interface.
sysfs files related to CPU power management:
/sys/kernel/debug/tegra_hotplug/max_cpus - maximum CPUs to use. User-configurable, default 4. This is not touched by the Android OS, and will remain in whatever state we set until reboot.
Set this to "1" to make the phone a lot less power-hungry and overheating.
At the cost of performance, of course.
*NOTE: second core will activate sometimes if this is set to "1", but 3rd and 4th cores are disabled for sure.
/sys/kernel/debug/tegra_hotplug/min_cpus - minimum number of CPUs to use.
This _is_ touched by the OS, and can not be set reliably.
/sys/kernel/debug/tegra_hotplug/stats - time each core spent active. Including 5-th "low-power" core.
e.g.:
Code:
cpu: G0 G1 G2 G3 LP
transitions: 26 12 0 0 25
time plugged: 3110 1222 0 0 95122
time-stamp: 4296183486
/sys/kernel/debug/cpuidle/lp2 - another stats interface.
/sys/module/cpu_tegra/parameters/cpu_user_cap - Max frequency cap for all cores. Default 1500000 (1.5GHz), can be set to any lower value to underclock.
But it is often set by the OS different values (most frequently, back to it's maximum). Maybe, changing this string in libhtc-opt2.so via hex editor can prevent system from changing it?
/sys/kernel/cluster/active - currently active CPU cluster. "LP" for low-power core, "G" for generic (normal) cores.
Can be changed manually, but is also modified by the system at will.
All above values can be changed from root shell via "echo 'value' > /sys/path/to/file"
Maybe, this will come handy to some ROM or CPU-monitoring app developers.
References:
Asus Transformer kernel source
[DEV] Enable 2D GPU rendering in HTC One X & about build.prop tweaks
some findings by phirenz

is there any way to request more use of the companion core?

In case anyone's wondering, I just found out that /sys/kernel/cluster/active must be opened as root even for reading; opening the file as any other user will not succeed.
The other files seem to allow reading as a standard user, however.

It woulod be great is someone created an app for setting number of CPUs. It is useful sometimes to set it to 1 when you are traveling and want to get max possible battery.
It would be even better if it was possible to disable all 4 cores and force system to use LP core only. It would be brilliant max power saving mode.

I've modified OS Monitor to support Tegra 3's stuff (temperature, number of cores and determining whether it is low power/general CPU in use) and my experience is that there's no or very little battery gains to be had because the other 3 cores are off most of the time anyway (when idle)
I'm using stock 1.28. The low power core doesn't seem to like being activated for more than a few seconds at a time, too.

I've modified OS Monitor to support Tegra 3's stuff
Click to expand...
Click to collapse
Can u share the apk here...xD???

thanks to the OP.....I don't have a One X but this info helped me to force all 4 cores of my Asus TF300T go online and offline as i wish.

schriss said:
It woulod be great is someone created an app for setting number of CPUs. It is useful sometimes to set it to 1 when you are traveling and want to get max possible battery.
It would be even better if it was possible to disable all 4 cores and force system to use LP core only. It would be brilliant max power saving mode.
Click to expand...
Click to collapse
use core control or francos kernel updater works for every custom kernel also stock kernel and you can choose how many cores...but battery life is not better with deactivated cores and soemetimes even worser -.-

I used to be able to do this, but now I'm using n3o kernel and I can't find the tegra_hotplug folder inside sys/kernel/debug. Help?

joeystar said:
I used to be able to do this, but now I'm using n3o kernel and I can't find the tegra_hotplug folder inside sys/kernel/debug. Help?
Click to expand...
Click to collapse
Man ask this in kernel thread not here....-.-
Sent from my HTC One X using xda app-developers app

5\6 cores is stopped

Hey everyone,
Recently my device is very slow. I downloaded the app CPU-Z and my surprise that 5 of 6 cores are not working.
Notably, the device is not on battery saving mode.
H815 Android 5.1 no rooted.
Does anyone know what the problem is and how to fix it? Because it is nearly impossible to use the device.
Thanks

Cores 5 and 6 is for Big Cpu and they will enable only when it need
If you are sure that it not work try Download Kernel adiutor then in cpu settings click on the checkbox cpu cores
Sent from my Xperia SP

HTC 10 Qualcomm Snapdragon 820 1.59GHz - Help

I am a newbie to this forum, not sure about things here.
your inputs on this would be highly appreciated.
I recently updated my HTC 10 to 7.0 and I see CPUZ where it shows the Processor i.e. 820 clocked at 1.59Ghz and 2 cores stopped. what could be the possible reason??
Posting the screenshot for further reference - UPDATE - I am not able to post a screenshot..

Snapdragon 820 uses the big.LITTLE architecture. Which means that the processor basically has two cluster. First cluster contains 2 cores which are low power cores, clocked at 1.6 GHz. These cores are used to carry out everyday tasks that do not require much resources. The other cluster has 2 High Performance cores, clocked at 2.2 GHz. These cores are only activated when needed. For example, while playing a game etc.
Hope this helps

I already updated my HTC 10 from 2.28.401.9 to 2.41.401.4 but have the same problem. First 2 cpu 1.59 and the other 2 stopped. Antutu and other benchmark show low points. Please I need help

It's due to SELinux changes in Android 7. If you change SELinux to permissive, then it will work again. Just "security changes" by Google.

Isn't it already answered?

RogerF81 said:
It's due to SELinux changes in Android 7. If you change SELinux to permissive, then it will work again. Just "security changes" by Google.
Click to expand...
Click to collapse
thanks for answer Sir.

LeNiPa said:
Isn't it already answered?
Click to expand...
Click to collapse
So sorry but I'm Newbie. Can I change SELinux to permissive without root ? Because I don't want to root it

caeisus said:
So sorry but I'm Newbie. Can I change SELinux to permissive without root ? Because I don't want to root it
Click to expand...
Click to collapse
No, this isn't possible.

Underclocked CPU values stay persistent

Hi there,
A while back, I decided to underclock the CPU on my rooted OnePlus 3 (A3003). Can't remember which app I used to do so, but I set the max freq. on my big cores to 1324 MHz, and on my little cores to 1036 MHz, which really helped with battery life.
Lately though, I felt the need of a bit more juice from the CPUs, so I tried bumping the frequencies up a little, using Kernel Auditor on RR-OS v5.8.4. However, the settings don't seem to save... 30 seconds after I bump them up, they revert back to the original underclocked values I have been using. Changing the CPU Governor works, as well as underclocking the CPU even lower; these settings remain saved. Disabling cores also works.
Does any of you have any suggestions? Has anyone encountered this as well?
Cheers.

Ricksis said:
Hi there,
A while back, I decided to underclock the CPU on my rooted OnePlus 3 (A3003). Can't remember which app I used to do so, but I set the max freq. on my big cores to 1324 MHz, and on my little cores to 1036 MHz, which really helped with battery life.
Lately though, I felt the need of a bit more juice from the CPUs, so I tried bumping the frequencies up a little, using Kernel Auditor on RR-OS v5.8.4. However, the settings don't seem to save... 30 seconds after I bump them up, they revert back to the original underclocked values I have been using. Changing the CPU Governor works, as well as underclocking the CPU even lower; these settings remain saved. Disabling cores also works.
Does any of you have any suggestions? Has anyone encountered this as well?
Cheers.
Click to expand...
Click to collapse
Could be a bug. But I really do not recommend to underclock or disable any cores. Perhaps reset the app that set those values and do a reboot.

Puddi_Puddin said:
Could be a bug. But I really do not recommend to underclock or disable any cores. Perhaps reset the app that set those values and do a reboot.
Click to expand...
Click to collapse
Do you mean reset Kernel Auditor ? I did the tweaks a while ago, I even switched a bunch of ROMs in the meanwhile. RR-OS doesn't come with a performance app, I had to get Kernel Auditor off the store, that came already reset, right?
I also tried changing the clock speeds with 3C CPU Manager, but the values jump back (as seen in the video posted).

You should follow mega unbrick guide method 2

Ricksis said:
Do you mean reset Kernel Auditor ? I did the tweaks a while ago, I even switched a bunch of ROMs in the meanwhile. RR-OS doesn't come with a performance app, I had to get Kernel Auditor off the store, that came already reset, right?
I also tried changing the clock speeds with 3C CPU Manager, but the values jump back (as seen in the video posted).
Click to expand...
Click to collapse
Pretty sure it is a kernel issue. You probably won't be able to solve It.

Bryandu13 said:
You should follow mega unbrick guide method 2
Click to expand...
Click to collapse
Puddi_Puddin said:
Pretty sure it is a kernel issue. You probably won't be able to solve It.
Click to expand...
Click to collapse
If the problem is in the Kernel, could I do a TWRP backup, follow the mega unbrick guide method 2, then restore the backup? Would that work?

you can try, but check the resust after the unbrick flash before restore the backup

Ricksis said:
If the problem is in the Kernel, could I do a TWRP backup, follow the mega unbrick guide method 2, then restore the backup? Would that work?
Click to expand...
Click to collapse
Mostly, recovery with backup turns you to same problem.
Better way is to backup the app data using root backups like
Oandbackup from f-droid,
Or titanium backup
Then, keep it safe on desktop and start method 2.
In this way, you may preserve data for required apps.
However, some apps may misbehave if you change from one ROM to another.

SivaMaxwell said:
root backups like Oandbackup from f-droid, Or titanium backup
Click to expand...
Click to collapse
So you advise me against TWRP? I would've done separate backups for system, app data, etc. in case something goes wrong.

After much struggle, I followed method 1 for bricked phones and reinstalled everything. Frequencies are still stuck on lower than max values...

Ricksis said:
After much struggle, I followed method 1 for bricked phones and reinstalled everything. Frequencies are still stuck on lower than max values...
Click to expand...
Click to collapse
Don't think otherwise.. just go to service centre, submit it stating that you have a malfunctioning motherboard.
I had exactly the same issue, this can't be resolved no matter what. So, I did the same.
Install Oneplus recovery and OOS and go to service centre. Tell them that your phone is not working as expected. Games are lagging and all apps are lagging. They will deny at first. You have to try to call the online team.
This is what I've done.
You can find my post
https://forum.xda-developers.com/oneplus-3/help/oneplus3-hanging-lagging-doesnt-respond-t3617057
Finally, they will change your motherboard and problem is solved.
The problem is in Motherboard.
Read it until last post.
Don't ever tell that you have rooted the phone. They keep on denying that your phone's warranty is gone, etc. So don't tell anything about root, under-clocking

Why Cpu All Core Working Without Use Any App?

Cpu Every Core Working Without Use Any App in Recent List

It shows 633Mhz for me (first four cores)
which rom you are on ?
however background processes of Android do take cpu usage

YasuHamed said:
It shows 633Mhz for me (first four cores)
which rom you are on ?
however background processes of Android do take cpu usage
Click to expand...
Click to collapse
I Think Other Core Should Stop When Not Use Any App in Recent

I does not seem to work like that. I have never seen my Redmi having a single idle CPU core
Sent from my whyred using XDA Labs

RupeshRN said:
I Think Other Core Should Stop When Not Use Any App in Recent
Click to expand...
Click to collapse
You think wrong

RupeshRN said:
I Think Other Core Should Stop When Not Use Any App in Recent
Click to expand...
Click to collapse
stock min freq is little 633 mhz big 1130mjz
underclocked can go to 300mhz both big and little.
you mean a hotplug.. when not in use all cores off then whn input turn on... unfortunatelly theres no hotplug for 636.. as they say in kernel settings balme qualcomm