Date: Tue, 12 Sep 2000 16:19:29 +0930 From: Greg Lehey <grog@lemis.com> To: Matthew Jacob <mjacob@feral.com> Cc: Joerg Micheel <joerg@cs.waikato.ac.nz>, 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: <20000912161928.C23948@wantadilla.lemis.com> In-Reply-To: <Pine.BSF.4.21.0009112334310.70549-100000@beppo.feral.com>; from mjacob@feral.com on Mon, Sep 11, 2000 at 11:34:55PM -0700 References: <20000912145255.A41113@cs.waikato.ac.nz> <Pine.BSF.4.21.0009112334310.70549-100000@beppo.feral.com>
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On Monday, 11 September 2000 at 23:34:55 -0700, Matt Jacob wrote: >>> 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". >> >> I liked the model Sun chose for Solaris. They have mutex', rw_locks, >> condition variables. I don't like semaphores. Mutexes are for short >> locks. Condition variables are for long-term waits, they are associated >> with a mutex. You can only sleep/wakeup a CV when holding the associated >> with it, which prevents races. When having to sleep on a CV the kernel >> would unlock the mutex and reaquire it for the running thread before >> returning. > > It encouraged very sloppy programming. That begs the question "can you elaborate?". 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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