Date: Wed, 8 Apr 1998 07:00:07 +0900 (JST) From: Michael Hancock <michaelh@cet.co.jp> To: John-Mark Gurney <gurney_j@resnet.uoregon.edu> Cc: FreeBSD Current <freebsd-current@FreeBSD.ORG> Subject: Re: kernel support for memory semaphores/locks... Message-ID: <Pine.SV4.3.95.980408065757.6997A-100000@parkplace.cet.co.jp> In-Reply-To: <19980407072623.51939@hydrogen.nike.efn.org>
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On Tue, 7 Apr 1998, John-Mark Gurney wrote: > I have writen a memory block based dynamic allocation system (mmalloc).. > I was planning on using a lock to prevent multiple processes from > accessing the allocation strutures... but the only real way is using > SYSV semaphores... and these are bad because it's silly to have all the overhead of a syscall to do locking. > so, how do we go about locking on a shared memory areas? > > after discussing this with a friend, ther HAS to be a lock based on a > shared memory location... the problem with storing the SYSV semaphore > semid is that there isn't an atomic way of obtaining the new semid > and putting it in a shared location after a machine reboot... /usr/src/share/doc/papers/newvm.ascii.gz describes an interface that was never implemented, but worth reading. Regards, Mike To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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