Re: libva decoding performance regression with kernel 4.0-rc

From: Chris Wilson
Date: Fri Apr 10 2015 - 02:23:47 EST

On Thu, Apr 09, 2015 at 09:00:43PM -0400, Olivier Crête wrote:
> Hello,
> Using an Atom E3845 board, we had a pretty bad performance regression
> when upgrading to 4.0-rc6 from 3.19. With the help of git bisect, I
> traced it back to commit 78a42377. Reverting this commit and subsequent
> related commits (b9ffd80, 71745376, etc) fixes the performance
> regression for me.

Can you please test

on your setup.

to get a baseline with nightly as that contains some fine tuning to the
batch allocations, which is pretty significant for libva on Atom (only
double clflushing one or two pages every batch rather than 128) and then
to see if the command parser tuning helps.

Hope this helps,

Chris Wilson, Intel Open Source Technology Centre
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