Date: Tue, 18 Jul 2000 20:16:21 +0100 From: David Malone <dwmalone@maths.tcd.ie> To: freebsd-bugs@freebsd.org Cc: bmilekic@dsuper.net, bright@wintelcom.net, iedowse@maths.tcd.ie, sheldonh@freebsd.org, jlemon@freebsd.org, wollman@freebsd.org Subject: Re: kern/19866: The mbuf subsystem refcount stuff. Message-ID: <200007182016.aa47290@salmon.maths.tcd.ie>
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> David, could you use your proximity to Ian to garner a > third opinion on this one? :-) Well, the current refcount code is definitely icky. I think everyone reckons it needs to be improved. My suggestion would be the following: 1) Abstract the management of external references using macros, but with no functional change initially. This might mean adding macros like Bosko's MEXT_IS_REF, MEXT_ADD_REF and MEXTADD - for the moment using the current referencing system. 2) While we're doing this, and testing it, we can assess any options people have for reference counting in the mbuf system. 3) Impliment whatever seems the most sensible, which should be relatively easy as most of work will just involve changing the macros. As far as I can make out, using the linked list to track mbuf references is not an unreasonable idea. NetBSD have been using it since 1997, see revision 1.23 of: http://www.FreeBSD.org/cgi/cvsweb.cgi/syssrc/sys/sys/mbuf.h?cvsroot=netbsd for details of when it was introduced. That's not to say there isn't a better system, but we have evidence this system can work. If this seems like a reasonable plan, I can work with Bosko to extract step 1 from his patches. David. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-bugs" in the body of the message
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