Received: from localhost (unknown [200.46.204.183]) by mail.postgresql.org (Postfix) with ESMTP id E09B46302C8 for ; Mon, 12 Jan 2009 03:17:53 -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 23204-08 for ; Mon, 12 Jan 2009 03:17:47 -0400 (AST) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from ey-out-2122.google.com (ey-out-2122.google.com [74.125.78.27]) by mail.postgresql.org (Postfix) with ESMTP id D26B662F5D9 for ; Mon, 12 Jan 2009 03:17:47 -0400 (AST) Received: by ey-out-2122.google.com with SMTP id d26so965047eyd.61 for ; Sun, 11 Jan 2009 23:17:46 -0800 (PST) Received: by 10.210.89.4 with SMTP id m4mr8011069ebb.114.1231743359151; Sun, 11 Jan 2009 22:55:59 -0800 (PST) Received: from oxford.xeocode.com.enterprisedb.com ([87.127.95.196]) by mx.google.com with ESMTPS id g11sm23083220gve.4.2009.01.11.22.55.57 (version=TLSv1/SSLv3 cipher=RC4-MD5); Sun, 11 Jan 2009 22:55:58 -0800 (PST) To: Tom Lane Cc: "Robert Haas" , "ITAGAKI Takahiro" , Postgres Subject: Re: posix_fadvise v22 In-Reply-To: <13517.1231737582@sss.pgh.pa.us> (Tom Lane's message of "Mon\, 12 Jan 2009 00\:19\:42 -0500") User-Agent: Gnus/5.11 (Gnus v5.11) Emacs/22.1 (gnu/linux) X-Draft-From: ("nnimap+imap.gmail.com:HACKERS" 53155) 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> <13517.1231737582@sss.pgh.pa.us> From: Gregory Stark Organization: EnterpriseDB Date: Mon, 12 Jan 2009 01:55:56 -0500 Message-ID: <87mydxm2rn.fsf@oxford.xeocode.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii 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: 200901/819 X-Sequence-Number: 131463 Tom Lane writes: > "Robert Haas" writes: >> OK, here's an update of Greg's patch with the runtime configure test >> ripped out, some minor documentation tweaks, and a few unnecessary >> whitespace diff hunks quashed. I think this is about ready for >> committer review. > > I've applied most of this, with a couple of notable revisions: > > 1. The runtime check on whether posix_fadvise works is really gone. > We'll see whether we need to put anything back, but I think our first > try should be under the assumption that it works. (BTW, I was wrong > in my earlier claim that the buildfarm wouldn't exercise posix_fadvise > by default --- the patch defaults to io_concurrency = 1 if fadvise > is available, so it will try to prefetch one page ahead.) > > 2. I fixed it so that setting effective_io_concurrency to zero disables > prefetching altogether; there was no way to do that in the patch as > submitted. Hm. the original intent was that effective_io_concurrency 1 meant no prefetching because there was only one drive. I wonder if that worked earlier and got lost along the way or if I always had this wrong. -- Gregory Stark EnterpriseDB http://www.enterprisedb.com Ask me about EnterpriseDB's 24x7 Postgres support!