Re: enable i915 rc6 save 7 watt on kernel 3.2
Am Donnerstag, 19. Januar 2012 schrieb Chen Wei:
> Hi List,
Hi Chen,
> Since recently upgraded to kernel 3.2, the core temperature on my
> laptop seems raised few degrees. An external power meter shows big
> difference in power consumption. The power usage raised from 15w on
> kernel 2.6.39, to 22w on kernel 3.2.1. A bit of google later, it was
> suggested that enable i915_enable_rc6 parameter may improves power
> consumption as well as graphic performance. And indeed it is, after
> put
> “i915.i915_enable_rc6=1” in grub config, the overall power usage drops
> to 15w, while the glxgears score increases from 39xxFPS to 47xxFPS.
>
> The system: i5-2410M, using integrated HD3000 GPU
> Debian Squeeze with backports xorg
Thanks for the hint.
It is no news for me:
merkaba:~> cat /etc/modprobe.d/i915-kms.conf
# Thorsten Leemhuis, Die Woche: Ungenutztes Stromsparpotenzial
# http://www.heise.de/open/artikel/Die-Woche-Ungenutztes-
Stromsparpotenzial-1361381.html
# Eugeni Dodonov, Intel Linux Graphics
# Following the open source road from Kernel to UI toolkits
# http://www.scribd.com/doc/73071712/Intel-Linux-Graphics
options i915 modeset=1 i915_enable_rc6=1 i915_enable_fbc=1 semaphores=1
The Heise Open article is also translated at H Open somewhere.
(I do not think that the other options make a big difference regarding
power consumption.)
There is also
# The Leading Cause Of The Recent Linux Kernel Power Problems
# http://www.phoronix.com/scan.php?page=article&item=linux_2638_aspm&num=2
GRUB_CMDLINE_LINUX_DEFAULT="pcie_aspm=force threadirqs"
but I didn´t found it to make much of a difference on my ThinkPad T520.
Aside from that glxgears is not, was not and likely never will be a
meaningful benchmark - it only utilizes a tiny fraction of OpenGL while
games and compositing managers use a different and larger set of OpenGL.
There are some benchmarks at Phoronix that show increased framerates. One
suggested explaination there is that due to the power savings mechanisms
like turbo boost for overclocking can be used more often and/or longer.
Ciao,
--
Martin 'Helios' Steigerwald - http://www.Lichtvoll.de
GPG: 03B0 0D6C 0040 0710 4AFA B82F 991B EAAC A599 84C7
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