Date: Tue, 12 Sep 2000 12:11:05 +0930 From: Greg Lehey <grog@lemis.com> To: Matthew Jacob <mjacob@feral.com> Cc: Frank Mayhar <frank@exit.com>, John Baldwin <jhb@pike.osd.bsdi.com>, Mark Murray <markm@FreeBSD.ORG>, FreeBSD-arch@FreeBSD.ORG Subject: Re: 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: <20000912121105.J88615@wantadilla.lemis.com> In-Reply-To: <Pine.LNX.4.21.0009111801490.25916-100000@zeppo.feral.com>; from mjacob@feral.com on Mon, Sep 11, 2000 at 06:02:26PM -0700 References: <200009120101.e8C11nN56928@realtime.exit.com> <Pine.LNX.4.21.0009111801490.25916-100000@zeppo.feral.com>
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On Monday, 11 September 2000 at 18:02:26 -0700, Matt Jacob wrote: >> Greg Lehey wrote: >>> I've been wondering whether we shouldn't associate mutexes with data >>> structures rather than code. It's possible that it would make it >>> easier to avoid deadlocks. Thoughts? >> >> Speaking as a BSD/OS (and former Unixware) developer: YES! > > Hmm. I would rather have assumed that this is what mutexes are > about. Semaphores gate entry in code. Mutexes provide locking on > data. Simple enough. That's a matter of definition. The big difference I see between a semaphore and a blocking "mutex" is that there's no count associated with the blocking "mutex": it's a degenerate case of a semaphore. At Tandem, we used semaphores exclusively (well, we had a mutex instruction, but it was really interrupt lockout). As far as I can recall, the semaphore counter was always 1, so the effect was identical to the current blocking "mutexes". Greg -- Finger grog@lemis.com for PGP public key See complete headers for address and phone numbers To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
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