Received: from localhost (unknown [200.46.204.183]) by mail.postgresql.org (Postfix) with ESMTP id 91B7364FCBE for ; Fri, 2 Jan 2009 15:26:27 -0400 (AST) Received: from mail.postgresql.org ([200.46.204.86]) by localhost (mx1.hub.org [200.46.204.183]) (amavisd-maia, port 10024) with ESMTP id 02247-09 for ; Fri, 2 Jan 2009 15:26:24 -0400 (AST) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from westnet.com (westnet.com [216.187.52.2]) by mail.postgresql.org (Postfix) with ESMTP id 4016064FC85 for ; Fri, 2 Jan 2009 15:26:24 -0400 (AST) Received: from westnet.com (localhost [127.0.0.1]) by westnet.com (8.14.0/8.14.0) with ESMTP id n02JPm0v017711; Fri, 2 Jan 2009 14:25:48 -0500 (EST) Received: from localhost (gsmith@localhost) by westnet.com (8.14.0/8.13.2/Submit) with ESMTP id n02JPlpO017698; Fri, 2 Jan 2009 14:25:47 -0500 (EST) X-Authentication-Warning: westnet.com: gsmith owned process doing -bs Date: Fri, 2 Jan 2009 14:25:47 -0500 (EST) From: Greg Smith X-X-Sender: gsmith@westnet.com To: Tom Lane cc: Robert Haas , Gregory Stark , ITAGAKI Takahiro , Postgres Subject: Re: posix_fadvise v22 In-Reply-To: <24481.1230910405@sss.pgh.pa.us> Message-ID: References: <8347.1229012970@sss.pgh.pa.us> <4136ffa0812110911x4914a951o6ca502879e3dede7@mail.gmail.com> <87k5a6tmy7.fsf@oxford.xeocode.com> <603c8f070901011230t1afa6644racb715b975078054@mail.gmail.com> <10658.1230843315@sss.pgh.pa.us> <603c8f070901011843p121e40afu35c4a7bdc51c051c@mail.gmail.com> <24481.1230910405@sss.pgh.pa.us> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=0 tagged_above=0 required=5 tests=none X-Spam-Level: X-Archive-Number: 200901/66 X-Sequence-Number: 130710 On Fri, 2 Jan 2009, Tom Lane wrote: > ISTM that you *should* be able to see an improvement on even > single-spindle systems, due to better overlapping of CPU and I/O effort. The earlier synthetic tests I did: http://archives.postgresql.org/pgsql-hackers/2008-09/msg01401.php Showed a substantial speedup even in the single spindle case on a couple of systems, but one didn't really seem to benefit. So we could theorize that Robert's test system is more like that one. If someone can help out with making a more formal test case showing this in action, I'll dig into the details of what's different between that system and the others. -- * Greg Smith gsmith@gregsmith.com http://www.gregsmith.com Baltimore, MD