Received: from localhost (unknown [200.46.204.183]) by developer.postgresql.org (Postfix) with ESMTP id 829432E0042 for ; Thu, 17 Apr 2008 21:26:32 -0300 (ADT) Received: from developer.postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.183]) (amavisd-maia, port 10024) with ESMTP id 51140-01 for ; Thu, 17 Apr 2008 21:26:26 -0300 (ADT) X-Greylist: from auto-whitelisted by SQLgrey-1.7.5 Received: from westnet.com (westnet.com [216.187.52.2]) by developer.postgresql.org (Postfix) with ESMTP id 774832E0037 for ; Thu, 17 Apr 2008 21:26:26 -0300 (ADT) Received: from westnet.com (localhost [127.0.0.1]) by westnet.com (8.14.0/8.14.0) with ESMTP id m3I0QPGw019650 for ; Thu, 17 Apr 2008 20:26:25 -0400 (EDT) Received: from localhost (gsmith@localhost) by westnet.com (8.14.0/8.13.2/Submit) with ESMTP id m3I0QPZQ019647 for ; Thu, 17 Apr 2008 20:26:25 -0400 (EDT) X-Authentication-Warning: westnet.com: gsmith owned process doing -bs Date: Thu, 17 Apr 2008 20:26:25 -0400 (EDT) From: Greg Smith X-X-Sender: gsmith@westnet.com To: pgsql-performance@postgresql.org Subject: Re: Strange behavior: pgbench and new Linux kernels In-Reply-To: Message-ID: References: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200804/255 X-Sequence-Number: 29748 On Thu, 17 Apr 2008, Matthew wrote: > The last message in the thread says that 2.6.25-rc6 has the problem nailed. > That was a month ago. So I guess, upgrade to 2.6.25, which was released > today. Ah, even more support for me to distrust everything I read. The change has flattened out things, so now the pgbench results are awful everywhere. On this benchmark 2.6.25 is the worst kernel yet: -bash-3.00$ pgbench -S -c 4 -t 10000 pgbench | grep excluding tps = 8619.710649 (excluding connections establishing) tps = 8664.321235 (excluding connections establishing) tps = 8671.973915 (excluding connections establishing) (was 18388 in 2.6.9 and 16621 in 2.6.23-3) -bash-3.00$ pgbench -S -c 8 -t 10000 pgbench | grep excluding tps = 9011.728765 (excluding connections establishing) tps = 9039.441796 (excluding connections establishing) tps = 9206.574000 (excluding connections establishing) (was 15760 in 2.6.9 and 15551 in 2.6.23-3) -bash-3.00$ pgbench -S -c 16 -t 10000 pgbench | grep excluding tps = 7063.710786 (excluding connections establishing) tps = 6956.266777 (excluding connections establishing) tps = 7120.971600 (excluding connections establishing) (was 14148 in 2.6.9 and 7311 in 2.6.23-3) -bash-3.00$ pgbench -S -c 32 -t 10000 pgbench | grep excluding tps = 7006.311636 (excluding connections establishing) tps = 6971.305909 (excluding connections establishing) tps = 7002.820583 (excluding connections establishing) (was 13647 in 2.6.9 and 7141 in 2.6.23-3) This is what happens when the kernel developers are using results from a MySQL tool to optimize things I guess. It seems I have a lot of work ahead of me here to nail down and report what's going on here. -- * Greg Smith gsmith@gregsmith.com http://www.gregsmith.com Baltimore, MD