[Bug 49603] [regression] Fullscreen video no longer smooth with GPU in low power mode

bugzilla-daemon at freedesktop.org bugzilla-daemon at freedesktop.org
Tue May 8 03:43:29 PDT 2012


--- Comment #2 from Simon Farnsworth <simon.farnsworth at onelan.co.uk> 2012-05-08 03:43:29 PDT ---
Created attachment 61213
  --> https://bugs.freedesktop.org/attachment.cgi?id=61213
Different route to spinning in preference to in-kernel waits for short fences

If Michel's patch helps, would you mind trying this patch instead? The
difference is that Michel's patch doesn't have the early abort if the kernel
says the GPU has completed the command batch we're waiting for, while this
patch does. Both patches will cause Mesa to spin 256 times before it goes to
sleep waiting for the GPU to have completed a command batch.

For background, I'm working with the Fusion E-350 chip; I'm thus CPU-limited.
The goal of the original patch is twofold:

1) Don't spin on CPU when you're going to have to wait for a long time for the
GPU to finish work - go to sleep waiting for the GPU to complete.

2) Don't keep spinning when the GPU has completed the command batch that
includes the fence - it's not going to change state again, absent bugs, so we
should cease spinning now.

If Michel's patch helps, and this patch does not, it indicates that there are
problems with attempting to wait in the kernel. If neither patch helps, we have
a deeper issue to diagnose.

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