Date: Wed, 13 Sep 2000 01:27:53 +0100 From: Brian Somers <brian@Awfulhak.org> To: Joerg Micheel <joerg@cs.waikato.ac.nz> Cc: Greg Lehey <grog@lemis.com>, Matthew Jacob <mjacob@feral.com>, Frank Mayhar <frank@exit.com>, John Baldwin <jhb@pike.osd.bsdi.com>, Mark Murray <markm@FreeBSD.org>, FreeBSD-arch@FreeBSD.org, brian@Awfulhak.org Subject: Re: Mutexes and semaphores (was: cvs commit: src/sys/conf files src/sys/sys random.h src/sys/dev/randomdev hash.c hash.h harvest.c randomdev.c yarrow.c yarro) Message-ID: <200009130027.e8D0RrH91664@hak.lan.Awfulhak.org> In-Reply-To: Message from Joerg Micheel <joerg@cs.waikato.ac.nz> of "Tue, 12 Sep 2000 16:25:06 %2B1200." <20000912162506.C41113@cs.waikato.ac.nz>
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> > What's the difference between a mutex and a semaphore?
>
> None, if it comes to the actual usage and implementation. Usually,
> people will use semaphores for locking blocks of code, mutexes for
> data structures. Not much of a difference in the end result, but
> locking data structures seems more natural to me.
I would tend to disagree.
A mutex is a way of guaranteeing that a resource isn't used more than
once. A semaphore is a mechanism for queuing a notification to a
(potentially) waiting process.
A mutex is just a binary semaphore, but I don't think that's
relevant.
--
Brian <brian@Awfulhak.org> <brian@[uk.]FreeBSD.org>
<http://www.Awfulhak.org>; <brian@[uk.]OpenBSD.org>
Don't _EVER_ lose your sense of humour !
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