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 565989DCCF0 for ; Mon, 6 Mar 2006 13:47:55 -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 65148-03 for ; Mon, 6 Mar 2006 13:47:54 -0400 (AST) X-Greylist: from auto-whitelisted by SQLgrey- Received: from tigger.fuhr.org (tigger.fuhr.org [63.214.45.158]) by postgresql.org (Postfix) with ESMTP id E65A39DCCB1 for ; Mon, 6 Mar 2006 13:47:52 -0400 (AST) Received: from winnie.fuhr.org (winnie.fuhr.org [10.1.0.1]) by tigger.fuhr.org (8.13.3/8.13.3) with ESMTP id k26HlhBV085206 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Mon, 6 Mar 2006 10:47:46 -0700 (MST) (envelope-from mfuhr@winnie.fuhr.org) Received: from winnie.fuhr.org (localhost [127.0.0.1]) by winnie.fuhr.org (8.13.4/8.13.4) with ESMTP id k26HlhSB013878; Mon, 6 Mar 2006 10:47:43 -0700 (MST) (envelope-from mfuhr@winnie.fuhr.org) Received: (from mfuhr@localhost) by winnie.fuhr.org (8.13.4/8.13.4/Submit) id k26HlgV1013877; Mon, 6 Mar 2006 10:47:42 -0700 (MST) (envelope-from mfuhr) Date: Mon, 6 Mar 2006 10:47:42 -0700 From: Michael Fuhr To: Joost Kraaijeveld Cc: "Pgsql-Performance (E-mail)" Subject: Re: Can anyone explain this pgbench results? Message-ID: <20060306174742.GA13788@winnie.fuhr.org> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Virus-Scanned: by amavisd-new at hub.org X-Spam-Status: No, score=0.122 required=5 tests=[AWL=0.122] X-Spam-Score: 0.122 X-Spam-Level: X-Archive-Number: 200603/39 X-Sequence-Number: 17476 On Mon, Mar 06, 2006 at 04:29:49PM +0100, Joost Kraaijeveld wrote: > Below are some results of running pgbench, run on a machine that > is doing nothing else than running PostgreSQL woth pgbench. The > strange thing is that the results are *constantly alternating* hight > (750-850 transactions)and low (50-80 transactions), no matter how > many test I run. If I wait a long time (> 5 minutes) after running > the test, I always get a hight score, followed by a low one, followed > by a high one, low one etc. The default checkpoint_timeout is 300 seconds (5 minutes). Is it coincidence that the "long time" between fast results is about the same? What's your setting? Are your test results more consistent if you execute CHECKPOINT between them? -- Michael Fuhr