Received: from localhost (unknown [200.46.208.211]) by mail.postgresql.org (Postfix) with ESMTP id 44816632DF6 for ; Fri, 20 Mar 2009 18:58:38 -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 95008-03 for ; Fri, 20 Mar 2009 18:58:32 -0300 (ADT) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from lists.commandprompt.com (host-159.commandprompt.net [207.173.203.159]) by mail.postgresql.org (Postfix) with ESMTP id EE66E632558 for ; Fri, 20 Mar 2009 18:58:33 -0300 (ADT) Received: from perhan.alvh.no-ip.org (200-126-101-194.bk7-dsl.surnet.cl [200.126.101.194]) (authenticated bits=0) by lists.commandprompt.com (8.13.8/8.13.8) with ESMTP id n2KM5CTR015353 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Fri, 20 Mar 2009 15:05:16 -0700 Received: by perhan.alvh.no-ip.org (Postfix, from userid 1000) id 9FBDC47CDF; Fri, 20 Mar 2009 17:58:13 -0400 (CLT) Date: Fri, 20 Mar 2009 17:58:13 -0400 From: Alvaro Herrera To: Scott Carey Cc: Robert Haas , "Jignesh K. Shah" , Greg Smith , Kevin Grittner , "pgsql-performance@postgresql.org" Subject: Re: Proposal of tunable fix for scalability of 8.4 Message-ID: <20090320215813.GR8313@alvh.no-ip.org> References: <603c8f070903191349p5e8fb00as2816581d584fcefd@mail.gmail.com> <20090320154601.GC8313@alvh.no-ip.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20090320154601.GC8313@alvh.no-ip.org> User-Agent: Mutt/1.5.18 (2008-05-17) X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.0 (lists.commandprompt.com [207.173.203.159]); Fri, 20 Mar 2009 15:05:17 -0700 (PDT) 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: 200903/307 X-Sequence-Number: 33229 Alvaro Herrera escribió: > Simon's explanation, however, is at odds with the code. > > http://git.postgresql.org/?p=postgresql.git;a=blob;f=src/backend/storage/lmgr/lwlock.c > > There is "queue jumping" in the regular (heavyweight) lock manager, but > that's a pretty different body of code. I'll just embarrass myself by pointing out that Neil Conway described this back in 2004: http://archives.postgresql.org//pgsql-hackers/2004-11/msg00905.php So Simon's correct. -- Alvaro Herrera http://www.CommandPrompt.com/ The PostgreSQL Company - Command Prompt, Inc.