Received: from localhost (unknown [200.46.208.211]) by mail.postgresql.org (Postfix) with ESMTP id 31492633E02 for ; Wed, 11 Mar 2009 22:32:43 -0300 (ADT) Received: from mail.postgresql.org ([200.46.204.86]) by localhost (mx1.hub.org [200.46.208.211]) (amavisd-maia, port 10024) with ESMTP id 54680-05 for ; Wed, 11 Mar 2009 22:32:32 -0300 (ADT) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) by mail.postgresql.org (Postfix) with ESMTP id BA066632B60 for ; Wed, 11 Mar 2009 22:32:38 -0300 (ADT) Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) by sss.pgh.pa.us (8.14.2/8.14.2) with ESMTP id n2C1WaO6029081; Wed, 11 Mar 2009 21:32:36 -0400 (EDT) To: "Kevin Grittner" cc: pgsql-performance@postgresql.org, "Jignesh K. Shah" Subject: Re: Proposal of tunable fix for scalability of 8.4 In-reply-to: <49B7F470.EE98.0025.0@wicourts.gov> References: <49B824DD.7090302@sun.com> <49B7F470.EE98.0025.0@wicourts.gov> Comments: In-reply-to "Kevin Grittner" message dated "Wed, 11 Mar 2009 17:27:12 -0500" Date: Wed, 11 Mar 2009 21:32:36 -0400 Message-ID: <29080.1236821556@sss.pgh.pa.us> From: Tom Lane X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=0.022 tagged_above=0 required=5 tests=AWL=0.022 X-Spam-Level: X-Archive-Number: 200903/110 X-Sequence-Number: 33032 "Kevin Grittner" writes: > I'm wondering about the testing methodology. Me too. This test case seems much too far away from real world use to justify diddling low-level locking behavior; especially a change that is obviously likely to have very negative effects in other scenarios. In particular, I think it would lead to complete starvation of would-be exclusive lockers in the face of competition from a steady stream of shared lockers. AFAIR the existing behavior was designed to reduce the odds of that, not for any other purpose. regards, tom lane