From owner-freebsd-current Wed Oct 23 14:40:10 2002 Delivered-To: freebsd-current@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id CA01B37B401; Wed, 23 Oct 2002 14:40:08 -0700 (PDT) Received: from rwcrmhc52.attbi.com (rwcrmhc52.attbi.com [216.148.227.88]) by mx1.FreeBSD.org (Postfix) with ESMTP id 20D4243E3B; Wed, 23 Oct 2002 14:40:08 -0700 (PDT) (envelope-from julian@elischer.org) Received: from InterJet.elischer.org ([12.232.206.8]) by rwcrmhc52.attbi.com (InterMail vM.4.01.03.27 201-229-121-127-20010626) with ESMTP id <20021023214007.JWUL28719.rwcrmhc52.attbi.com@InterJet.elischer.org>; Wed, 23 Oct 2002 21:40:07 +0000 Received: from localhost (localhost.elischer.org [127.0.0.1]) by InterJet.elischer.org (8.9.1a/8.9.1) with ESMTP id OAA37325; Wed, 23 Oct 2002 14:27:41 -0700 (PDT) Date: Wed, 23 Oct 2002 14:27:40 -0700 (PDT) From: Julian Elischer To: Jeff Roberson Cc: Seigo Tanimura , Bruce Evans , current@FreeBSD.ORG, tanimura@FreeBSD.ORG Subject: Re: Dynamic growth of the buffer and buffer page reclaim In-Reply-To: <20021023163758.R22147-100000@mail.chesapeake.net> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG 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