Date: Wed, 27 Mar 2002 16:51:57 -0500 (EST) From: John Baldwin <jhb@FreeBSD.org> To: Julian Elischer <julian@elischer.org> Cc: arch@freebsd.org Subject: RE: SMP safe reference counting Message-ID: <XFMail.20020327165157.jhb@FreeBSD.org> In-Reply-To: <Pine.BSF.4.21.0203271150430.47944-100000@InterJet.elischer.org>
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On 27-Mar-2002 Julian Elischer wrote: > > [please remove -smp from your reply] > > Once again on the SMP list a lock is being used to make a reference count > safe. I'd like to re-raise the issue of a safe reference counting > fascility. > > what would be the semantics? I have refcount.patch :) What would be nice is to first implement atomic_fetchadd() (xadd on 486+, some hack on 386, fetchadd on ia64, similar to atomic_add on sparc64, alpha, and powerpc I believe, basically it would add a value to a memory location and return the result). You can then use taht for the reference_release (or whatever you call it). We could also use that to get rid of the really bloated debug version that uses a mutex and have a much smaller debug version that still uses atomic ops. -- John Baldwin <jhb@FreeBSD.org> <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve!" - http://www.FreeBSD.org/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
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