linux-kernel - Re: libva decoding performance regression with kernel 4.0-rc

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Date:	Fri, 10 Apr 2015 19:25:59 -0400
From:	Olivier Crête <olivier.crete@...labora.com>
To:	Chris Wilson <chris@...is-wilson.co.uk>
Cc:	Daniel Vetter <daniel.vetter@...el.com>,
	Jani Nikula <jani.nikula@...ux.intel.com>,
	David Airlie <airlied@...ux.ie>,
	intel-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org
Subject: Re: libva decoding performance regression with kernel 4.0-rc

Hello,

Thanks for the quick reply!

With my real use-cases:

1. 9x 720p60 mpeg2 videos
 - 4.0-rc6: ~12 frames per second are on time
 - 4.0-rc6 + reverts: a stable 45 frames per second are on time
 - 044307a9: 40-45 frames per second are on time
 - 0a24802a: 45-46 frames per second are on time

2. 1080i30 mpeg2 videos
 - 4.0-rc6:  5 videos
 - 044307a9: 10 videos
 - 0a24802a: 10 videos

So you basically beat my baseline too, good job, thanks a lot! Any
chance you can sneak this into 4.0 ?

Olivier

On Fri, 2015-04-10 at 07:23 +0100, Chris Wilson wrote:
> 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
> 
> http://cgit.freedesktop.org/~ickle/linux-2.6/log/?h=for-olivier-crete
> 
> on your setup.
> 
> First
> http://cgit.freedesktop.org/~ickle/linux-2.6/commit/?h=for-olivier-crete&id=044307a99b418258ac0d775460d73b20b80277c1
> 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
> http://cgit.freedesktop.org/~ickle/linux-2.6/commit/?h=for-olivier-crete&id=0a24802a5b61403b887ce401ce3efd52f5fd1eac
> to see if the command parser tuning helps.
> 
> Hope this helps,
> -Chris
> 

-- 
Olivier Crête
olivier.crete@...labora.com

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