[Libva] High CPU usage in __i915_wait_request when encoding video

[Steinar H. Gunderson]

On Mon, Nov 02, 2015 at 10:28:53AM +0100, Steinar H. Gunderson wrote:
>> vaSyncSurface() just calls drm_intel_bo_wait_rendering() to make sure
>> all GPU operations with the surface are finished.
>> drm_intel_bo_wait_rendering() is implemented with SET_DOMAIN ioctl(), I
>> don't think it waits with busylooping.
> Then why does it show up in perf?

I also noticed that gen6_ring_get_seqno uses some CPU, again from
vaSyncSurface() -> (something) -> drm_intel_gem_bo_start_gtt_access
-> drmIoctl.

/* Steinar */
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