Date: Wed, 23 Oct 2002 14:27:40 -0700 (PDT) From: Julian Elischer <julian@elischer.org> To: Jeff Roberson <jroberson@chesapeake.net> Cc: 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: <Pine.BSF.4.21.0210231418520.36940-100000@InterJet.elischer.org> In-Reply-To: <20021023163758.R22147-100000@mail.chesapeake.net>
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On Wed, 23 Oct 2002, Jeff Roberson wrote: > > I do, however, like the page unwiring idea. As long as it's not too > expensive. I have been somewhat disappointed that the buffer cache's > buffers are hands off for the vm. I'm confused about your approach > though. I think that the rewire function is unnecessary. You could move > this code into allocbuf() which would limit the number of times that you > have to make a pass over this list and keep the maintenance of it in a > more central place. This would also remove the need for truncating the > buf. > 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 The number of slots was going to be somehow tunable but I don't remember the details. When you wanted to access a buffer, it was mapped for you (unless already mapped).. It would be unmapped when it's slot was needed for something else. WHen you accessed a buffer already mapped it would move it back to the top of the list. Various events could pre-unmap a buffer. e.g. the related vm object was closed. (0 references). To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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