From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Robert Hancock <hancockr@shaw.ca>
Cc: linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: sched_yield() makes OpenLDAP slow
Date: Sat, 20 Aug 2005 14:18:46 +1000 [thread overview]
Message-ID: <4306AF26.3030106@yahoo.com.au> (raw)
In-Reply-To: <4306A176.3090907@shaw.ca>
Robert Hancock wrote:
>
> I fail to see how sched_yield is going to be very helpful in this
> situation. Since that call can sleep from a range of time ranging from
> zero to a long time, it's going to give unpredictable results.
>
Well, not sleep technically, but yield the CPU for some undefined
amount of time.
> It seems to me that this sort of thing is why we have POSIX pthread
> synchronization primitives.. sched_yield is basically there for a
> process to indicate that "what I'm doing doesn't matter much, let other
> stuff run". Any other use of it generally constitutes some kind of hack.
>
In SCHED_OTHER mode, you're right, sched_yield is basically meaningless.
In a realtime system, there is a very well defined and probably useful
behaviour.
Eg. If 2 SCHED_FIFO processes are running at the same priority, One can
call sched_yield to deterministically give the CPU to the other guy.
--
SUSE Labs, Novell Inc.
Send instant messages to your online friends http://au.messenger.yahoo.com
next prev parent reply other threads:[~2005-08-20 4:18 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <4D8eT-4rg-31@gated-at.bofh.it>
2005-08-20 3:20 ` sched_yield() makes OpenLDAP slow Robert Hancock
2005-08-20 4:18 ` Nick Piggin [this message]
2005-08-20 18:38 ` Howard Chu
2005-08-20 20:57 ` Lee Revell
2005-08-20 21:24 ` Howard Chu
2005-08-21 0:36 ` Nick Piggin
2005-08-21 11:33 ` Nikita Danilov
2005-08-22 8:06 ` Howard Chu
2005-08-20 21:50 ` Lee Revell
2005-08-21 1:04 ` Robert Hancock
2005-08-22 11:44 ` linux-os (Dick Johnson)
2005-08-22 14:26 ` Robert Hancock
2005-08-23 11:17 ` linux-os (Dick Johnson)
2005-08-23 12:07 ` Denis Vlasenko
2005-08-24 3:37 ` Lincoln Dale
2006-01-24 22:59 e100 oops on resume Stefan Seyfried
2006-01-24 23:21 ` Mattia Dongili
2006-01-25 9:02 ` Olaf Kirch
2006-01-25 12:11 ` Olaf Kirch
2006-01-25 13:51 ` sched_yield() makes OpenLDAP slow Howard Chu
2006-01-25 14:38 ` Robert Hancock
2006-01-25 17:49 ` Christopher Friesen
2006-01-26 1:07 ` David Schwartz
2006-01-26 8:30 ` Helge Hafting
2006-01-26 9:01 ` Nick Piggin
2006-01-26 10:50 ` Nikita Danilov
[not found] <5uZqb-4fo-15@gated-at.bofh.it>
2006-01-14 22:47 ` Robert Hancock
-- strict thread matches above, loose matches on Subject: below --
2006-01-14 19:29 Howard Chu
[not found] <43057641.70700@symas.com.suse.lists.linux.kernel>
[not found] ` <17157.45712.877795.437505@gargle.gargle.HOWL.suse.lists.linux.kernel>
[not found] ` <430666DB.70802@symas.com.suse.lists.linux.kernel>
2005-08-20 13:48 ` Andi Kleen
2005-08-21 19:47 ` Florian Weimer
2005-08-22 5:09 ` Howard Chu
2005-08-22 13:06 ` Andi Kleen
2005-08-22 18:47 ` Howard Chu
2005-08-22 13:20 ` Florian Weimer
2005-08-22 23:19 ` Howard Chu
2005-08-19 6:03 Howard Chu
2005-08-19 6:34 ` Nick Piggin
2005-08-19 6:59 ` Chris Wedgwood
2005-08-19 22:45 ` Howard Chu
2005-08-19 10:21 ` Nikita Danilov
2005-08-19 23:10 ` Howard Chu
2005-08-20 13:23 ` Nikita Danilov
2005-08-20 19:49 ` Howard Chu
2005-08-20 22:08 ` Nikita Danilov
[not found] <4303DB48.8010902@develer.com.suse.lists.linux.kernel>
[not found] ` <20050818010703.GA13127@nineveh.rivenstone.net.suse.lists.linux.kernel>
[not found] ` <4303F967.6000404@yahoo.com.au.suse.lists.linux.kernel>
[not found] ` <43054D9A.7090509@develer.com.suse.lists.linux.kernel>
2005-08-19 3:19 ` Andi Kleen
2005-08-19 3:30 ` Bernardo Innocenti
2005-08-18 0:50 Bernardo Innocenti
2005-08-18 0:47 ` Con Kolivas
2005-08-18 10:48 ` Maciej Soltysiak
2005-08-18 1:07 ` Joseph Fannin
2005-08-18 2:25 ` Bernardo Innocenti
2005-08-18 2:58 ` Nick Piggin
2005-08-19 3:10 ` Bernardo Innocenti
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