linux-kernel - Re: CFS review

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Message-ID: <14311.1188333968@turing-police.cc.vt.edu>
Date:	Tue, 28 Aug 2007 16:46:08 -0400
From:	Valdis.Kletnieks@...edu
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Al Boldi <a1426z@...ab.com>, Ingo Molnar <mingo@...e.hu>,
	Peter Zijlstra <peterz@...radead.org>,
	Mike Galbraith <efault@....de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org
Subject: Re: CFS review

On Mon, 27 Aug 2007 22:05:37 PDT, Linus Torvalds said:
> 
> 
> On Tue, 28 Aug 2007, Al Boldi wrote:
> > 
> > No need for framebuffer.  All you need is X using the X.org vesa-driver.  
> > Then start gears like this:
> > 
> >   # gears & gears & gears &
> > 
> > Then lay them out side by side to see the periodic stallings for ~10sec.
> 
> I don't think this is a good test.
> 
> Why?
> 
> If you're not using direct rendering, what you have is the X server doing 
> all the rendering, which in turn means that what you are testing is quite 
> possibly not so much about the *kernel* scheduling, but about *X-server* 
> scheduling!

I wonder - can people who are doing this as a test please specify whether
they're using an older X that has the libX11 or the newer libxcb code? That
may have a similar impact as well.

(libxcb is pretty new - it landed in Fedora Rawhide just about a month ago,
after Fedora 7 shipped.  Not sure what other distros have it now...)

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