linux-kernel - Re: [PATCH 2.6.20-rc4 0/4] futexes functionalities and improvements

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Message-ID: <45ACEBDF.60602@redhat.com>
Date:	Tue, 16 Jan 2007 07:14:39 -0800
From:	Ulrich Drepper <drepper@...hat.com>
To:	Pierre Peiffer <pierre.peiffer@...l.net>
CC:	LKML <linux-kernel@...r.kernel.org>, Ingo Molnar <mingo@...e.hu>,
	Andrew Morton <akpm@...l.org>, Jakub Jelinek <jakub@...hat.com>
Subject: Re: [PATCH 2.6.20-rc4 0/4] futexes functionalities and improvements

Pierre Peiffer wrote:
> I've run this bench 1000 times with pipe and 800 groups.
> Here are the results:

This is not what I'm mostly concerned about.  The patches create a
bottleneck since _all_ processes use the same resource.  Plus, this code
has to be run on a machine with multiple processors to get RFOs into play.

So, please do this: on an SMP (4p or more) machine, rig the test so that
it runs quite a while.  Then, in a script, start the program a bunch of
times, all in parallel.  Have the script wait until all program runs are
done and time the time until the last program finishes.

-- 
➧ Ulrich Drepper ➧ Red Hat, Inc. ➧ 444 Castro St ➧ Mountain View, CA ❖

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