Date: Sat, 27 Jun 1998 12:12:25 -0400 (EDT) From: "David E. Brooks Jr" <dbj@iglou.com> To: freebsd-questions@FreeBSD.ORG, freebsd-stable@FreeBSD.ORG Subject: mmap() and process synchronization Message-ID: <Pine.BSF.3.96.980627114056.1717A-100000@localhost>
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I'm looking into using mmap() for sharing memory (read/write) between multiple process, which of course means I'll need a means of synchronization. Not being overly fond of the System V semaphore routines, I looked for alternatives. Particularly intriguing was the reference to a MAP_HASSEMAPHORE flag in the mmap(2) man page. The 'newvm' paper (in /usr/share/doc/papers) was informative, so I eagerly went looking for the mset()/mclear() code to see how it was implemented. Sadly they're not implemented in 2.2.6-STABLE. This is too bad since mset()/mclear() look far faster in concept than the System V alternative. Is there any plan to implement mset(), mclear(), msleep() and mwakeup()? It doesn't seem they would be overly difficult to implement correctly (but I've never done any kernel-level work, either). This leads me to my second question: Foregoing the availability of mset() and company, what is considered the "canonical' method of process synchronization when using mmap()? System V semaphores? flock(2)? (Neither of those approaches are particularly appealing). -- Dave -- David E. Brooks Jr dbj@iglou.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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