Bug 59895 - Weird clocking issue with atom laptop with gen3 intel graphics
Summary: Weird clocking issue with atom laptop with gen3 intel graphics
Status: RESOLVED DUPLICATE of bug 30364
Alias: None
Product: xorg
Classification: Unclassified
Component: Driver/intel (show other bugs)
Version: git
Hardware: x86 (IA32) Linux (All)
: medium enhancement
Assignee: Chris Wilson
QA Contact: Intel GFX Bugs mailing list
Depends on:
Reported: 2013-01-26 10:58 UTC by sergio.callegari
Modified: 2013-01-26 11:14 UTC (History)
0 users

See Also:
i915 platform:
i915 features:


Description sergio.callegari 2013-01-26 10:58:51 UTC

this is a minor thing, an 'enhancement'.

On this rather underpowered machine, if you run something that is intensive only for the GPU, but not for the CPU the opengl rendering speed becomes orrible. And you have a weird situation where loading the machine improves the graphical performance rather than reducing it.

Sample case using glxgears. I know that it is not a benchmark, but here I am using it precisely because it loads the GPU and only very modestly the CPU.

Due to vsync, glxgears should give approximately 60 fps.

If I start glxgears, with nothing else running, I see 60fps for the first 5 seconds, then 20-30 fps. At this point, if I launch something else that makes the cpu work, glxgears rises back to 60fps, if I stop the extra CPU load glxgears goes back to 30fps.

I suspect that when the cpu is not loaded enough the CPU clock drops down also bringing down the GPU clock or the memory clock with it and this degrades the GPU performance a lot. Should the GPU driver be able to tell the kernel 'I'm making the GPU work hard, do not drop down the clock speed?'
Comment 1 Chris Wilson 2013-01-26 11:14:15 UTC

*** This bug has been marked as a duplicate of bug 30364 ***

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