Received: from maia.hub.org (maia-2.hub.org [200.46.204.251]) by mail.postgresql.org (Postfix) with ESMTP id C7AE21337B81 for ; Fri, 5 Nov 2010 17:39:09 -0300 (ADT) Received: from mail.postgresql.org ([200.46.204.86]) by maia.hub.org (mx1.hub.org [200.46.204.251]) (amavisd-maia, port 10024) with ESMTP id 46620-01 for ; Fri, 5 Nov 2010 20:39:02 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from mail.anarazel.de (mail.anarazel.de [217.115.131.40]) by mail.postgresql.org (Postfix) with ESMTP id 8F37C1336971 for ; Fri, 5 Nov 2010 17:39:02 -0300 (ADT) Received: by mail.anarazel.de (Postfix, from userid 108) id 3F4B7448008; Fri, 5 Nov 2010 21:39:00 +0100 (CET) Received: from anarazel.de (g225137037.adsl.alicedsl.de [92.225.137.37]) by mail.anarazel.de (Postfix) with ESMTPSA id 1F67A448005; Fri, 5 Nov 2010 21:38:56 +0100 (CET) Received: by anarazel.de (Postfix, from userid 1000) id 1B4221C0111; Fri, 5 Nov 2010 21:38:54 +0100 (CET) From: Andres Freund To: pgsql-performance@postgresql.org Subject: Re: Major Linux performance regression; shouldn't we be worried about RHEL6? Date: Fri, 5 Nov 2010 21:38:54 +0100 User-Agent: KMail/1.13.5 (Linux/2.6.37-rc1-andres-00005-gd88c092; KDE/4.5.1; x86_64; ; ) Cc: Josh Berkus References: <4CD465D8.4070007@agliodbs.com> In-Reply-To: <4CD465D8.4070007@agliodbs.com> MIME-Version: 1.0 Content-Type: Text/Plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <201011052138.54791.andres@anarazel.de> X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=-1.91 tagged_above=-10 required=5 tests=BAYES_00=-1.9, T_RP_MATCHES_RCVD=-0.01 X-Spam-Level: X-Archive-Number: 201011/66 X-Sequence-Number: 41090 On Friday 05 November 2010 21:15:20 Josh Berkus wrote: > All, > > Domas (of Facebook/Wikipedia, MySQL geek) pointed me to this report: > > http://www.phoronix.com/scan.php?page=article&item=linux_perf_regressions&n I guess thats the O_DSYNC thingy. See the "Defaulting wal_sync_method to fdatasync on Linux for 9.1?" (performance) and "Revert default wal_sync_method to fdatasync on Linux 2.6.33+" on hackers. O_DSYNC got finally properly implemented on linux with 2.6.33 (and thus 2.6.32- rc1). > um=1 http://www.phoronix.com/scan.php?page=article&item=ext4_then_now&num=6 That one looks pretty uninteresting. Barriers are slower then no barriers. No surprise there. Andres