Arch Linux

bastardo

Member

Registered: 2008-11-29

Posts: 15

intel_pstate Bug in Kernel 3.18.6-1-ARCH, ivy bridge (possibly more)

Hi everyone,

I'm quite certain by now that the userspace controls for the intel_pstate driver are broken for my ivybridge processor. It would be nice, if some other people could test this on their Sandy Bridge and newer hardware.
Bug: I cannot turn off the turbo or set the max and min performance thresholds.

Details:
Setting /sys/devices/system/cpu/intel_pstate/no_turbo
(and the other controls, but this is easiest to test)
has no effect for me.

My setup:

   vendor_id	: GenuineIntel
   cpu family	: 6
   model		: 58
   model name	: Intel(R) Core(TM) i7-3632QM CPU @ 2.20GHz
   stepping	: 9
   microcode	: 0x1b

This processor has a 3.2 GHz Turbo, it also has some intermediate turbo step at 2.6 GHz, if some cores are idle and others not.

cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor 
> powersave
cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_driver 
> intel_pstate
cat /sys/devices/system/cpu/intel_pstate/no_turbo 
> 1

To reproduce, be root,

echo 1 > /sys/devices/system/cpu/intel_pstate/no_turbo
watch -n 1 "cat /proc/cpuinfo | grep MHz"

and stress the CPU.

Thanks and best,
Bas

Raynman

Member

Registered: 2011-10-22

Posts: 1,539

Re: intel_pstate Bug in Kernel 3.18.6-1-ARCH, ivy bridge (possibly more)

Turning off turbo like that works for me (also pstate/powersave).

vendor_id	: GenuineIntel
cpu family	: 6
model		: 58
model name	: Intel(R) Core(TM) i5-3475S CPU @ 2.90GHz
stepping	: 9
microcode	: 0x1b

bastardo

Member

Registered: 2008-11-29

Posts: 15

Re: intel_pstate Bug in Kernel 3.18.6-1-ARCH, ivy bridge (possibly more)

Turning off turbo like that works for me (also pstate/powersave).

Thank you! Then we already know that not the complete Ivy Bridge series is affected. Is there maybe anybody with exactly my cpu?

graysky

Wiki Maintainer

From: :wq

Registered: 2008-12-01

Posts: 10,597

Website

Re: intel_pstate Bug in Kernel 3.18.6-1-ARCH, ivy bridge (possibly more)

Haswell here and no problem.

vendor_id	: GenuineIntel
cpu family	: 6
model		: 60
model name	: Intel(R) Core(TM) i7-4790K CPU @ 4.00GHz
stepping	: 3
microcode	: 0x1c

Setting of 0 has all cores @ 4.40 GHz and setting of 1 has them capped to 4.00 GHz.  Will test on an Ivy i7-3770k in a few and post back.

Last edited by graysky (2015-02-19 20:09:40)

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CPU-optimized Linux-ck packages @ Repo-ck  • AUR packages • Zsh and other configs

graysky

Wiki Maintainer

From: :wq

Registered: 2008-12-01

Posts: 10,597

Website

Re: intel_pstate Bug in Kernel 3.18.6-1-ARCH, ivy bridge (possibly more)

Sorry, the Ivy is overclocked so the turbo setting is ignored in the BIOS.

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CPU-optimized Linux-ck packages @ Repo-ck  • AUR packages • Zsh and other configs

graysky

Wiki Maintainer

From: :wq

Registered: 2008-12-01

Posts: 10,597

Website

Re: intel_pstate Bug in Kernel 3.18.6-1-ARCH, ivy bridge (possibly more)

@op - Is this any help for you: https://bbs.archlinux.org/viewtopic.php … 8#p1505708
???

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CPU-optimized Linux-ck packages @ Repo-ck  • AUR packages • Zsh and other configs

bastardo

Member

Registered: 2008-11-29

Posts: 15

Re: intel_pstate Bug in Kernel 3.18.6-1-ARCH, ivy bridge (possibly more)

@op - Is this any help for you: https://bbs.archlinux.org/viewtopic.php?id=193983

This looks extremely promising - I can't recompile the kernel currently, because I really need my laptop for work and I don't want to risk it until Saturday.
I will check the thread for updates very frequently until then, because it sounds like a jackpot.