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

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Message-ID: <20150410062331.GE20904@nuc-i3427.alporthouse.com>
Date:	Fri, 10 Apr 2015 07:23:31 +0100
From:	Chris Wilson <chris@...is-wilson.co.uk>
To:	Olivier Crête <olivier.crete@...labora.com>
Cc:	Brad Volkin <bradley.d.volkin@...el.com>,
	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

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

-- 
Chris Wilson, Intel Open Source Technology Centre
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