X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org Received: from localhost (av.hub.org [200.46.204.144]) by postgresql.org (Postfix) with ESMTP id B80199DD54F for ; Tue, 21 Mar 2006 06:32:22 -0400 (AST) Received: from postgresql.org ([200.46.204.71]) by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) with ESMTP id 25141-10 for ; Tue, 21 Mar 2006 06:32:23 -0400 (AST) X-Greylist: from auto-whitelisted by SQLgrey- Received: from noel.decibel.org (noel.decibel.org [67.100.216.10]) by postgresql.org (Postfix) with ESMTP id 70FA39DD54C for ; Tue, 21 Mar 2006 06:32:17 -0400 (AST) Received: by noel.decibel.org (Postfix, from userid 1001) id AE86756427; Tue, 21 Mar 2006 04:32:20 -0600 (CST) Received: (hashcash-sendmail, from uid 1001); Tue, 21 Mar 2006 04:32:20 -0600 Date: Tue, 21 Mar 2006 04:32:19 -0600 From: "Jim C. Nasby" To: Vivek Khera Cc: Postgresql Performance Subject: Re: Best OS & Configuration for Dual Xeon w/4GB & Adaptec RAID 2200S Message-ID: <20060321103219.GD15742@pervasive.com> References: <20060317221116.GA14661@juniper.net> <8F6490E1-64E2-406B-A559-7DA8BA1EB197@khera.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <8F6490E1-64E2-406B-A559-7DA8BA1EB197@khera.org> X-Operating-System: FreeBSD 6.0-RELEASE-p4 amd64 X-Distributed: Join the Effort! http://www.distributed.net User-Agent: Mutt/1.5.11 X-Hashcash: 1:20:060321:vivek@khera.org::AYOpbj62Jo32N0iU:001rxk X-Hashcash: 1:20:060321:pgsql-performance@postgresql.org::llE8jcg1Dmcl40y/:00000 0000000000000000000000005yMC X-Virus-Scanned: by amavisd-new at hub.org X-Spam-Status: No, score=0.108 required=5 tests=[AWL=0.108] X-Spam-Score: 0.108 X-Spam-Level: X-Archive-Number: 200603/375 X-Sequence-Number: 17812 On Mon, Mar 20, 2006 at 02:15:22PM -0500, Vivek Khera wrote: > I think FreeBSD has a hard upper limit on the total ram it will use > for disk cache. I haven't been able to get reliable, irrefutable, > answers about it, though. It does not. Any memory in the inactive queue is effectively your 'disk cache'. Pages start out in the active queue, and if they aren't used fairly frequently they will move into the inactive queue. From there they will be moved to the cache queue, but only if the cache queue falls below a certain threshold, because in order to go into the cache queue the page must be marked clean, possibly incurring a write to disk. AFAIK pages only go into the free queue if they have been completely released by all objects that were referencing them, so it's theoretically posisble for that queue to go to 0. -- Jim C. Nasby, Sr. Engineering Consultant jnasby@pervasive.com Pervasive Software http://pervasive.com work: 512-231-6117 vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461