Date: Thu, 21 Jan 2010 05:31:23 -0500 (EST)
From: Daniel Eischen <deischen@freebsd.org>
To: Bernard van Gastel <bvgastel@bitpowder.com>
Cc: =?iso-8859-1?Q?Dag-Erling_Sm=F8rgrav?= <des@des.no>, freebsd-hackers@freebsd.org
Subject: Re: pthread_{mutex,cond} & fifo/starvation/scheduling policy
Message-ID: <Pine.GSO.4.64.1001210526560.28344@sea.ntplx.net>
In-Reply-To: <72CE899C-5941-4659-B922-DC65BB0CE67D@bitpowder.com>
References: <71A129DC-68A0-46C3-956D-C8AFF1BA29E1@bitpowder.com> <86hbqifip8.fsf@ds4.des.no> <72CE899C-5941-4659-B922-DC65BB0CE67D@bitpowder.com>
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On Thu, 21 Jan 2010, Bernard van Gastel wrote: > But the descheduling of threads if the mutex is not available is done > by the library. And especially the order of rescheduling of the > threads (thats what I'm interested in). Or am I missing something in > the sys/kern/sched files (btw I don't have the umtx file). No, it's done by the kernel. Threads block on a umtx in the kernel, and they are also woken up by the kernel. The threads library does not wake up a specific thread - it just calls into the kernel to unlock the umtx and the kernel decides which thread to wake up. You should probably see src/sys/kern/kern_umtx.c. -- DE
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