Received: from localhost (unknown [200.46.204.183]) by developer.postgresql.org (Postfix) with ESMTP id 8ACF52E002D for ; Thu, 17 Apr 2008 15:15:41 -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 53489-02 for ; Thu, 17 Apr 2008 15:15:36 -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 C185F2E0054 for ; Thu, 17 Apr 2008 15:15:35 -0300 (ADT) Received: from westnet.com (localhost [127.0.0.1]) by westnet.com (8.14.0/8.14.0) with ESMTP id m3HIFVE8023483; Thu, 17 Apr 2008 14:15:31 -0400 (EDT) Received: from localhost (gsmith@localhost) by westnet.com (8.14.0/8.13.2/Submit) with ESMTP id m3HIFVfg023478; Thu, 17 Apr 2008 14:15:31 -0400 (EDT) X-Authentication-Warning: westnet.com: gsmith owned process doing -bs Date: Thu, 17 Apr 2008 14:15:31 -0400 (EDT) From: Greg Smith X-X-Sender: gsmith@westnet.com To: Jeffrey Baker cc: 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: 200804/247 X-Sequence-Number: 29740 On Thu, 17 Apr 2008, Jeffrey Baker wrote: > This has been discussed recently on linux-kernel. Excellent pointer, here's direct to the interesting link there: http://marc.info/?l=linux-kernel&m=120574906013029&w=2 Ingo's test system has 16 cores and dives hard at >32 clients; my 4-core system has trouble with >8 clients; looks like the same behavior. And it seems to be fixed in 2.6.25, which just "shipped" literally in the middle of my testing last night. Had I waited until today to grab a kernel I probably would have missed the whole thing. I'll have to re-run to be sure (I just love running a kernel with the paint still wet) but it looks like the conclusion here is "don't run PostgreSQL on kernels 2.6.23 or 2.6.24". Good thing I already hated FC8. If all these kernel developers are using sysbench, we really should get that thing cleaned up so it runs well with PostgreSQL. -- * Greg Smith gsmith@gregsmith.com http://www.gregsmith.com Baltimore, MD