linux-kernel - Re: [REPORT] cfs-v4 vs sd-0.44

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Message-Id: <200704220054.58639.vda.linux@googlemail.com>
Date:	Sun, 22 Apr 2007 00:54:58 +0200
From:	Denis Vlasenko <vda.linux@...glemail.com>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Con Kolivas <kernel@...ivas.org>, Willy Tarreau <w@....eu>,
	William Lee Irwin III <wli@...omorphy.com>,
	linux-kernel@...r.kernel.org,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Nick Piggin <npiggin@...e.de>, Mike Galbraith <efault@....de>,
	Arjan van de Ven <arjan@...radead.org>,
	Peter Williams <pwil3058@...pond.net.au>,
	Thomas Gleixner <tglx@...utronix.de>, caglar@...dus.org.tr,
	Gene Heskett <gene.heskett@...il.com>
Subject: Re: [REPORT] cfs-v4 vs sd-0.44

On Saturday 21 April 2007 18:00, Ingo Molnar wrote:
> correct. Note that Willy reniced X back to 0 so it had no relevance on 
> his test. Also note that i pointed this change out in the -v4 CFS 
> announcement:
> 
> || Changes since -v3:
> ||
> ||  - usability fix: automatic renicing of kernel threads such as 
> ||    keventd, OOM tasks and tasks doing privileged hardware access
> ||    (such as Xorg).
> 
> i've attached it below in a standalone form, feel free to put it into 
> SD! :)

But X problems have nothing to do with "privileged hardware access".
X problems are related to priority inversions between server and client
processes, and "one server process - many client processes" case.

I think syncronous nature of Xlib (clients cannot fire-and-forget
their commands to X server, with Xlib each command waits for ACK
from server) also add some amount of pain.
--
vda
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