Received: from localhost (unknown [200.46.204.183]) by mail.postgresql.org (Postfix) with ESMTP id 4897764FC36 for ; Fri, 2 Jan 2009 06:08:54 -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 14241-03 for ; Fri, 2 Jan 2009 06:08:51 -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 3B1F064FC1E for ; Fri, 2 Jan 2009 06:08:51 -0400 (AST) Received: from westnet.com (localhost [127.0.0.1]) by westnet.com (8.14.0/8.14.0) with ESMTP id n02A8ED5026778; Fri, 2 Jan 2009 05:08:14 -0500 (EST) Received: from localhost (gsmith@localhost) by westnet.com (8.14.0/8.13.2/Submit) with ESMTP id n02A8DW3026772; Fri, 2 Jan 2009 05:08:13 -0500 (EST) X-Authentication-Warning: westnet.com: gsmith owned process doing -bs Date: Fri, 2 Jan 2009 05:08:13 -0500 (EST) From: Greg Smith X-X-Sender: gsmith@westnet.com To: Robert Haas cc: Tom Lane , Gregory Stark , ITAGAKI Takahiro , Postgres Subject: Re: posix_fadvise v22 In-Reply-To: <603c8f070901011843p121e40afu35c4a7bdc51c051c@mail.gmail.com> 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> 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: 200901/44 X-Sequence-Number: 130688 On Thu, 1 Jan 2009, Robert Haas wrote: > The only thing I haven't been able to do is demonstrate that this change > actually produces a performance improvement. Either I'm testing the > wrong thing, or it just doesn't provide any benefit on a single-spindle > system. When I did a round of testing on the earlier prefetch test program Greg Stark put together, one of my single-spindle Linux system didn't show any real benefit. So as long as you didn't see performance degrade, your not seeing any improvement isn't bad news. I've got a stack of hardware I can do performance testing of this patch on, what I haven't been able to find time for is setting up any sort of test harness right now. If you or Greg have any benchmark or test program you could suggest that should show off the improvements here, I'd be glad to run it on a bunch of systems and report back--I've already got a stack of candidate ones I ran the earlier tests on to compare results against. -- * Greg Smith gsmith@gregsmith.com http://www.gregsmith.com Baltimore, MD