Date: Thu, 11 Jul 2002 16:10:32 -0700 (PDT) From: Julian Elischer <julian@elischer.org> To: Bosko Milekic <bmilekic@unixdaemons.com> Cc: Luigi Rizzo <rizzo@icir.org>, freebsd-net@FreeBSD.ORG Subject: Re: mbuf external buffer reference counters Message-ID: <Pine.BSF.4.21.0207111606440.47612-100000@InterJet.elischer.org> In-Reply-To: <20020711171255.A19014@unixdaemons.com>
next in thread | previous in thread | raw e-mail | index | archive | help
On Thu, 11 Jul 2002, Bosko Milekic wrote: > > Well, I can use a different map, I guess (I use a different map for > mbufs in order to not let huge cluster allocations eat up all of the > address space reserved for mbufs). However, it seems that jumbo bufs > and clusters are logically equivalent (your driver will either use one > or the other) so it would make sense to have them share the same > `chunk' of address space. > > As for the gaps, they are quite huge. I think we calculated a week or > so ago when discussing jumbo bufs that we would probably end up > allocating them in chunks of 3 or 4 at a time. So that would mean at > least ~9 page 'holes' in the address space from which clusters are > allocated, so that would mean ~18 counters wasted, at least, for every > hole. With the number of jumbo bufs we would have, that can really > add up. Don't forget that "external" does not neccesarily mean "cluster". I still consider the method used in (hmm was it NetBSD or OSF/1?) to be very good.. mbufs that referred to the same object were linked together. I forget the details exactly. maybe someone else can remember.. it did it without ref counts somehow.. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?Pine.BSF.4.21.0207111606440.47612-100000>