Date: Wed, 23 Oct 2002 23:50:35 +0200 From: Poul-Henning Kamp <phk@critter.freebsd.dk> To: Julian Elischer <julian@elischer.org> Cc: Jeff Roberson <jroberson@chesapeake.net>, Seigo Tanimura <tanimura@axe-inc.co.jp>, Bruce Evans <bde@zeta.org.au>, current@FreeBSD.ORG, tanimura@FreeBSD.ORG Subject: Re: Dynamic growth of the buffer and buffer page reclaim Message-ID: <47189.1035409835@critter.freebsd.dk> In-Reply-To: Your message of "Wed, 23 Oct 2002 14:27:40 PDT." <Pine.BSF.4.21.0210231418520.36940-100000@InterJet.elischer.org>
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In message <Pine.BSF.4.21.0210231418520.36940-100000@InterJet.elischer.org>, Ju lian Elischer writes: >Bill Jolitz had a plan for 386BSD where all the buffers were nearly >always unmapped from KVM. He was going to have a number of slots >available for mapping them which would be used in a lifo order This entire area needs to be rethought. And by "rethought" I really mean try to redesign it from scratch to match our current needs and see what that leads to compared to the stuff we have. On of my first TODO after the 5.x/6.x branch is to give struct bio the ability to communicate in a vector of separate pages, not necessarily mapped. This gives us a scatter gather ability in the entire disk I/O path. This opens up a host of possibilities for things like clustering, background writes (using copy-on-write pages) etc etc etc. Needless to say, it will also drastically change the working environment for struct buf. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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