Received: from localhost (unknown [200.46.208.211]) by mail.postgresql.org (Postfix) with ESMTP id 44359633EAB for ; Fri, 13 Mar 2009 14:16:52 -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 31764-01 for ; Fri, 13 Mar 2009 14:16:47 -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 CF466633EAC for ; Fri, 13 Mar 2009 14:16:47 -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 n2DHGi94012293; Fri, 13 Mar 2009 13:16:44 -0400 (EDT) To: Robert Haas cc: Scott Carey , Greg Smith , "Jignesh K. Shah" , Kevin Grittner , "pgsql-performance@postgresql.org" Subject: Re: Proposal of tunable fix for scalability of 8.4 In-reply-to: <603c8f070903121829r31cf1472ha9876e5c480a542e@mail.gmail.com> References: <603c8f070903121829r31cf1472ha9876e5c480a542e@mail.gmail.com> Comments: In-reply-to Robert Haas message dated "Thu, 12 Mar 2009 21:29:52 -0400" Date: Fri, 13 Mar 2009 13:16:44 -0400 Message-ID: <12292.1236964604@sss.pgh.pa.us> From: Tom Lane X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=0.018 tagged_above=0 required=5 tests=AWL=0.018 X-Spam-Level: X-Archive-Number: 200903/166 X-Sequence-Number: 33088 Robert Haas writes: > I think that changing the locking behavior is attacking the problem at > the wrong level anyway. Right. By the time a patch here could have any effect, you've already lost the game --- having to deschedule and reschedule a process is a large cost compared to the typical lock hold time for most LWLocks. So it would be better to look at how to avoid blocking in the first place. regards, tom lane