Gentoo Forums
Gentoo Forums
Gentoo Forums
Quick Search: in
[SOLVED] lower frequency with intel pstate
View unanswered posts
View posts from last 24 hours

 
Reply to topic    Gentoo Forums Forum Index Kernel & Hardware
View previous topic :: View next topic  
Author Message
potuz
Guru
Guru


Joined: 30 Jan 2010
Posts: 378

PostPosted: Mon Feb 09, 2015 6:04 pm    Post subject: [SOLVED] lower frequency with intel pstate Reply with quote

This is the first time that I am using the intel pstate driver on a new computer with a core i5 CPU. I noticed that the CPU is always running at maximal speed. I managed to lower this via

#echo 1 > /sys/devices/system/cpu/intel_pstate/no_turbo

but now the CPU runs at the maximum nominal speed (without turbo). Is there anyway to lower this? As I understand from Documentation/cpu-freq/intel_pstate.txt the governor is irrelevant since the speed is decided by the processor. In anycase it's set to powersave.


Last edited by potuz on Wed Feb 11, 2015 11:06 am; edited 1 time in total
Back to top
View user's profile Send private message
potuz
Guru
Guru


Joined: 30 Jan 2010
Posts: 378

PostPosted: Tue Feb 10, 2015 2:48 am    Post subject: Reply with quote

I found out that adding to /sys/class/thermal/coolling_device0/cur_state will lower the frequency of the cpus and hence the temperature of the system.
Back to top
View user's profile Send private message
hephooey
n00b
n00b


Joined: 24 Feb 2003
Posts: 74

PostPosted: Tue Feb 10, 2015 11:52 pm    Post subject: Reply with quote

First of all, I do not know how did you check you CPU frequency. I would suggest to try turbostat in the kernel source or powertop to get the precise statistics. pstate will turbo cpus if there is something keeps the system busy. The averaged frequency you got in turbostat when the system is idle should be a few MHz.
If you just really want to lower the cpu frequency and do not care about the speed of the system, try to tune the number in sys/devices/system/cpu/intel_pstate/max_perf_pct.
Back to top
View user's profile Send private message
potuz
Guru
Guru


Joined: 30 Jan 2010
Posts: 378

PostPosted: Wed Feb 11, 2015 1:42 am    Post subject: Reply with quote

I get the current frequency directly from /proc/cpuinfo and with conky freq_g which I think it does the same. In any case it is true that this system is kept busy but I do not know by what. Running top shows a kworker taking up 74% of one core constantly and this is from a fresh boot. Taking a couple of traces with echo -l > /proc/sysrq-trigger show always the corresponding kworker at some acpi function (acpi_os_execute_deferred, acpi_ns_search_and_enter) etc... since this is a very new laptop it's going to be a pain to debug this.
Back to top
View user's profile Send private message
potuz
Guru
Guru


Joined: 30 Jan 2010
Posts: 378

PostPosted: Wed Feb 11, 2015 11:05 am    Post subject: Reply with quote

After looking for a bit I found a firmware bug that was affecting this machine. After upgrading the firmware the issue is resolved and the CPU throttles down to normal indices. Good thing I kept Mac OS X on this one. https://bugzilla.kernel.org/show_bug.cgi?id=85881
Back to top
View user's profile Send private message
Display posts from previous:   
Reply to topic    Gentoo Forums Forum Index Kernel & Hardware All times are GMT
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum