From: Hubert Tonneau <hubert.tonneau@fullpliant.org>
To: linux-kernel@vger.kernel.org
Subject: Re: Network slowdown due to CFS
Date: Mon, 01 Oct 2007 22:27:52 GMT [thread overview]
Message-ID: <07E3AEH11@briare1.fullpliant.org> (raw)
Ingo Molnar wrote:
>
> Really, i have never seen a _single_ mainstream app where the use of
> sched_yield() was the right choice.
Pliant 'FastSem' semaphore implementation (as oppsed to 'Sem') uses 'yield'
http://old.fullpliant.org/
Basically, if the ressource you are protecting with the semaphore will be held
for a significant time, then a full semaphore might be better, but if the
ressource will be held just a fiew cycles, then light aquiering might bring best
result because the most significant cost is in aquiering/releasing.
So the aquiering algorithm for fast semaphores might be:
try to aquire with a hardware atomic read and set instruction, then if it fails,
call yield then retry (at least on a single processor single core system).
next reply other threads:[~2007-10-01 21:37 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-10-01 22:27 Hubert Tonneau [this message]
-- strict thread matches above, loose matches on Subject: below --
2007-09-26 8:52 Network slowdown due to CFS Martin Michlmayr
2007-09-26 9:34 ` Ingo Molnar
2007-09-26 9:47 ` Ingo Molnar
2007-09-26 10:08 ` Martin Michlmayr
2007-09-26 10:18 ` Ingo Molnar
2007-09-26 10:20 ` Mike Galbraith
2007-09-26 10:23 ` Mike Galbraith
2007-09-26 10:48 ` Martin Michlmayr
2007-09-26 11:21 ` Ingo Molnar
2007-09-26 11:29 ` Martin Michlmayr
2007-09-26 12:00 ` David Schwartz
2007-09-26 13:31 ` Ingo Molnar
2007-09-26 15:40 ` Stephen Hemminger
2007-09-26 15:46 ` Stephen Hemminger
2007-09-27 9:30 ` Jarek Poplawski
2007-09-27 9:46 ` Ingo Molnar
2007-09-27 12:27 ` Jarek Poplawski
2007-09-27 13:31 ` Ingo Molnar
2007-09-27 14:42 ` Jarek Poplawski
2007-09-28 6:10 ` Nick Piggin
2007-10-01 8:43 ` Jarek Poplawski
2007-10-01 16:25 ` Ingo Molnar
2007-10-01 16:49 ` David Schwartz
2007-10-01 17:31 ` Ingo Molnar
2007-10-01 18:23 ` David Schwartz
2007-10-02 6:06 ` Ingo Molnar
2007-10-02 6:47 ` Andi Kleen
2007-10-03 8:02 ` Jarek Poplawski
2007-10-03 8:16 ` Ingo Molnar
2007-10-03 8:56 ` Jarek Poplawski
2007-10-03 9:10 ` Ingo Molnar
2007-10-03 9:50 ` Jarek Poplawski
2007-10-03 10:55 ` Dmitry Adamushko
2007-10-03 10:58 ` Dmitry Adamushko
2007-10-03 11:20 ` Jarek Poplawski
2007-10-03 11:22 ` Ingo Molnar
2007-10-03 11:40 ` Jarek Poplawski
2007-10-07 7:18 ` Ingo Molnar
2007-10-04 5:33 ` Casey Dahlin
2007-10-02 6:08 ` Ingo Molnar
2007-10-02 6:26 ` Ingo Molnar
2007-10-01 19:53 ` Arjan van de Ven
2007-10-01 22:17 ` David Schwartz
2007-10-01 22:35 ` Arjan van de Ven
2007-10-01 22:44 ` David Schwartz
2007-10-01 22:55 ` Arjan van de Ven
2007-10-02 15:37 ` David Schwartz
2007-10-03 7:15 ` Jarek Poplawski
2007-10-03 11:31 ` Helge Hafting
2007-10-04 0:31 ` Rusty Russell
2007-10-01 16:55 ` Chris Friesen
2007-10-01 17:09 ` Ingo Molnar
2007-10-01 17:45 ` Chris Friesen
2007-10-02 9:03 ` Jarek Poplawski
2007-10-02 13:39 ` Jarek Poplawski
2007-10-02 9:26 ` Jarek Poplawski
2007-09-27 9:49 ` Ingo Molnar
2007-09-27 10:54 ` Martin Michlmayr
2007-09-27 10:56 ` Ingo Molnar
2007-09-27 11:12 ` Martin Michlmayr
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