very bad performance

Chris Wilson chris at
Wed Aug 8 11:35:12 PDT 2012

On Wed, 8 Aug 2012 16:42:36 +0300, Mihai Donțu <mihai.dontu at> wrote:
> On Tue, 07 Aug 2012 17:28:40 +0100 Chris Wilson wrote:
> > There have bugs where the cacheability flags of the pages in memory
> > have been lost over suspend and resume, and where the GPU became
> > stuck in a low power mode. So such degradation of performance over
> > time is not unheard of. One of the key questions is if we have no
> > errors reported how do the performance characteristics of the system
> > vary over time? Running x11perf along with the benchmarks from
> > intel-gpu-tools would be a good way to get some results that should
> > help give some insight as to what changes. Along with comparing perf
> > profiles over time.
> > 
> Are there any specific x11perf tests I should be looking at? Or should
> I just script the run of all supported tests? There are many. :-)

"-copywinwin500 -putimage500 -aa10text" should give enough coverage to
suggest the next step.
> I'm looking into intel-gpu-tools too. Btw: how can I find out if the
> GPU is stuck in a low power mode?

cat /sys/kernel/debug/dri/0/i915_drpc_info, the CAGF field is the
current frquency (presuming you have a GPU that supports dynamic

Chris Wilson, Intel Open Source Technology Centre

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