From owner-freebsd-hackers Sun Jan 26 21:44:51 2003 Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id E2E5C37B401 for ; Sun, 26 Jan 2003 21:44:49 -0800 (PST) Received: from kientzle.com (h-66-166-149-50.SNVACAID.covad.net [66.166.149.50]) by mx1.FreeBSD.org (Postfix) with ESMTP id A163543F18 for ; Sun, 26 Jan 2003 21:44:48 -0800 (PST) (envelope-from kientzle@acm.org) Received: from acm.org (UGLY.x.kientzle.comg [66.166.149.51] (may be forged)) by kientzle.com (8.11.3/8.11.3) with ESMTP id h0R5iKR18377; Sun, 26 Jan 2003 21:44:20 -0800 (PST) (envelope-from kientzle@acm.org) Message-ID: <3E34C734.8010801@acm.org> Date: Sun, 26 Jan 2003 21:44:20 -0800 From: Tim Kientzle Reply-To: kientzle@acm.org User-Agent: Mozilla/5.0 (X11; U; FreeBSD i386; en-US; rv:0.9.6) Gecko/20011206 X-Accept-Language: en-us, en MIME-Version: 1.0 To: "Brian T. Schellenberger" Cc: Sean Hamilton , hackers@FreeBSD.ORG Subject: Re: Random disk cache expiry References: <000501c2c4dd$f43ed450$16e306cf@slugabed.org> <3E34A6BB.2090601@acm.org> <001801c2c5c0$5666de10$16e306cf@slugabed.org> <200301270019.44066.bschellenberger@nc.rr.com> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG Brian T. Schellenberger wrote: > This to me is imminently sensible. > In fact there seem like two rules that have come up in this discussion: > > 1. For sequential access, you should be very hesitant to throw away > *another* processes blocks, at least once you have used more than, say, > 25% of the cache or potential cache. > > 2. For sequential access, you should stop caching before you throw away > your own blocks. If it's sequential it is, it seems to me, always a > lose to throw away your *own* processes older bllocks on thee same > file. The question isn't "should I throw away blocks or not?". Obviously, the ideal is to keep everything in the cache, but that's not possible. The question is "what blocks should be discarded?" You've ruled out quite a few possibilities here. What blocks _should_ be discarded? Tim Kientzle To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message