Received: from localhost (unknown [200.46.204.187]) by postgresql.org (Postfix) with ESMTP id B43719FC99B for ; Fri, 26 Oct 2007 16:08:29 -0300 (ADT) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.187]) (amavisd-maia, port 10024) with ESMTP id 86257-08 for ; Fri, 26 Oct 2007 16:08:20 -0300 (ADT) X-Greylist: from auto-whitelisted by SQLgrey-1.7.5 Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) by postgresql.org (Postfix) with ESMTP id 580209FC998 for ; Fri, 26 Oct 2007 16:08:22 -0300 (ADT) Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) by sss.pgh.pa.us (8.14.1/8.14.1) with ESMTP id l9QJ8GbN024693; Fri, 26 Oct 2007 15:08:16 -0400 (EDT) To: "Jignesh K. Shah" cc: Josh Berkus , pgsql-performance@postgresql.org, Gregory Stark , pgsql-hackers@postgresql.org Subject: Re: [HACKERS] 8.3beta1 testing on Solaris In-reply-to: <472219D6.6030001@sun.com> References: <4720FB72.8060800@sun.com> <871wbi95nb.fsf@oxford.xeocode.com> <29721.1193359867@sss.pgh.pa.us> <200710251956.56744.josh@agliodbs.com> <2139.1193369168@sss.pgh.pa.us> <4721ED75.7090607@sun.com> <47220B96.4080009@sun.com> <472219D6.6030001@sun.com> Comments: In-reply-to "Jignesh K. Shah" message dated "Fri, 26 Oct 2007 12:46:14 -0400" Date: Fri, 26 Oct 2007 15:08:16 -0400 Message-ID: <24692.1193425696@sss.pgh.pa.us> From: Tom Lane X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200710/304 X-Sequence-Number: 27326 "Jignesh K. Shah" writes: > So the ratio of reads vs writes to clog files is pretty huge.. It looks to me that the issue is simply one of not having quite enough CLOG buffers. Your first run shows 8 different pages being fetched and the second shows 10. Bearing in mind that we "pin" the latest CLOG page into buffers, there are only NUM_CLOG_BUFFERS-1 buffers available for older pages, so what we've got here is thrashing for the available slots. Try increasing NUM_CLOG_BUFFERS to 16 and see how it affects this test. regards, tom lane