From owner-freebsd-current Wed Nov 1 22:54:48 2000 Delivered-To: freebsd-current@freebsd.org Received: from cs.utep.edu (mail.cs.utep.edu [129.108.5.3]) by hub.freebsd.org (Postfix) with ESMTP id CD94D37B4CF for ; Wed, 1 Nov 2000 22:54:44 -0800 (PST) Received: from gecko (gecko [129.108.5.51]) by cs.utep.edu (8.10.1/8.10.1) with ESMTP id eA26sax12910; Wed, 1 Nov 2000 23:54:36 -0700 (MST) Date: Wed, 1 Nov 2000 23:54:37 -0700 (MST) From: X-Sender: janb@gecko To: David Greenman Cc: freebsd-current@FreeBSD.ORG Subject: Re: current paging strategy In-Reply-To: <200011020631.WAA12676@implode.root.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG Interesting. THis needs about two bytes per page for the counter? JAn On Wed, 1 Nov 2000, David Greenman wrote: > >What paging strategy does FreeBSD currently use? Is it LRU or some > >approximation to it? How much memory does this strategy take up in its > >current implementation? > > It's probably nothing like anything you've heard of before. It's closest > to LOU (least often used). We look at the page's reference flag and > increment/decrement a counter depending on it. The rate that we look at > the reference flag is also roughly proportional to the rate at which new > pages are needed. This algorithm has proven to be extremely effective and > does much better than simple LRU. > > -DG > > David Greenman > Co-founder, The FreeBSD Project - http://www.freebsd.org > President, TeraSolutions, Inc. - http://www.terasolutions.com > Pave the road of life with opportunities. > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message