Created attachment 8537372 [details] compositor_flush.png While profiling 4k h.264 video playback, I have observed that the overhead of flush calls in the compositor are causing significant overhead of about 21% of the firefox.exe process. This may be a factor in the choppy playback. http://dxr.mozilla.org/mozilla-central/source/gfx/layers/d3d11/CompositorD3D11.cpp#923 See the attached call stack from WPA showing the path to flush. Removing the flush shifts the available CPU resources to other work, but I'm not sure if this will have drawbacks elsewhere. According to MSDN, these calls to Flush() shouldn't be necessary. http://msdn.microsoft.com/en-us/library/windows/desktop/ff476425%28v=vs.85%29.aspx
Milan, radar'ing this with you...
We have been known to add Flush() to make things more robust, with more drivers, but I don't know about these ones in particular. Bas would.
In most cases we shouldn't be flushing excessively, if we are, we can fix that, in general though, the amount of CPU time spent in 'flush' can be very misleading, as it's when most of the work actually happens anyway.