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<b><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - [IVB/HSW/BYT-M/BDW] GpuTest_v0.5_triangle is slower by 10%~50% in fullscreen than in windowed & composited mode"
href="https://bugs.freedesktop.org/show_bug.cgi?id=80705#c1">Comment # 1</a>
on <a class="bz_bug_link
bz_status_NEW "
title="NEW --- - [IVB/HSW/BYT-M/BDW] GpuTest_v0.5_triangle is slower by 10%~50% in fullscreen than in windowed & composited mode"
href="https://bugs.freedesktop.org/show_bug.cgi?id=80705">bug 80705</a>
from <span class="vcard"><a class="email" href="mailto:eero.t.tamminen@intel.com" title="Eero Tamminen <eero.t.tamminen@intel.com>"> <span class="fn">Eero Tamminen</span></a>
</span></b>
<pre>According to Mengmeng, this issue happens only with DRI3, not DRI2.
Can you check with intel_gpu_top (on BYT where it works fine) what is the
"render" value both in fullscreen and windowed mode?
I.e. is GPU 100% utilized in both cases, like it's with DRI2.
FYI: In an unrelated test it was noticed that with DRI3, X still does
occasionally Vsync wait although test had zeroed swap interval.
According to Chris' comment on that test:
---------
The current implementation requires 4 buffers to run the entire pipeline in an
synchronous manner, Keith is only feeding in 3 (from mesa/src/glx/dri3_glx.c)
and so forces the synchronization.
---------
-> With Vsync, test wouldn't be using GPU fully.</pre>
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