X-Original-To: pgsql-performance-postgresql.org@postgresql.org Received: from localhost (wm.hub.org [200.46.204.128]) by postgresql.org (Postfix) with ESMTP id 8C9A49FA50D; Fri, 21 Jul 2006 10:42:51 -0300 (ADT) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.128]) (amavisd-new, port 10024) with ESMTP id 42004-10; Fri, 21 Jul 2006 13:42:47 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey- X-Greylist: from auto-whitelisted by SQLgrey- Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) by postgresql.org (Postfix) with ESMTP id C95FC9FA4A8; Fri, 21 Jul 2006 10:42:47 -0300 (ADT) Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) by sss.pgh.pa.us (8.13.6/8.13.6) with ESMTP id k6LDgjGA021890; Fri, 21 Jul 2006 09:42:46 -0400 (EDT) To: Robert Lor cc: Tatsuo Ishii , pgsql-hackers@postgresql.org, pgsql-performance@postgresql.org Subject: Re: Sun Donated a Sun Fire T2000 to the PostgreSQL In-reply-to: <44C088C8.9050303@sun.com> References: <20060617.101521.95879771.t-ishii@sraoss.co.jp> <10226.1150511655@sss.pgh.pa.us> <20060617.111838.39487910.t-ishii@sraoss.co.jp> <20060713.180234.45872055.t-ishii@sraoss.co.jp> <8669.1153422118@sss.pgh.pa.us> <44C088C8.9050303@sun.com> Comments: In-reply-to Robert Lor message dated "Fri, 21 Jul 2006 00:56:56 -0700" Date: Fri, 21 Jul 2006 09:42:45 -0400 Message-ID: <21889.1153489365@sss.pgh.pa.us> From: Tom Lane X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200607/207 X-Sequence-Number: 20067 Robert Lor writes: > I ran pgbench and fired up a DTrace script using the lwlock probes we've > added, and it looks like BufMappingLock is the most contended lock, but > CheckpointStartLocks are held for longer duration! Those numbers look a bit suspicious --- I'd expect to see some of the LWLocks being taken in both shared and exclusive modes, but you don't show any such cases. You sure your script is counting correctly? Also, it'd be interesting to count time spent holding shared lock separately from time spent holding exclusive. regards, tom lane