Received: from localhost (unknown [200.46.208.211]) by mail.postgresql.org (Postfix) with ESMTP id 4F57A632FAB for ; Thu, 12 Mar 2009 15:28:18 -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 00171-07 for ; Thu, 12 Mar 2009 15:28:04 -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 65BF6632969 for ; Thu, 12 Mar 2009 15:28:03 -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 n2CIS1ar012917; Thu, 12 Mar 2009 14:28:01 -0400 (EDT) To: Scott Carey cc: Kevin Grittner , "pgsql-performance@postgresql.org" , "Jignesh K. Shah" Subject: Re: Proposal of tunable fix for scalability of 8.4 In-reply-to: References: Comments: In-reply-to Scott Carey message dated "Thu, 12 Mar 2009 10:39:05 -0700" Date: Thu, 12 Mar 2009 14:28:01 -0400 Message-ID: <12916.1236882481@sss.pgh.pa.us> From: Tom Lane X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=0.02 tagged_above=0 required=5 tests=AWL=0.020 X-Spam-Level: X-Archive-Number: 200903/135 X-Sequence-Number: 33057 Scott Carey writes: > They are not meaningless. It is certainly more to understand, but the test is entirely valid without that. In a CPU bound / RAM bound case, as concurrency increases you look for the throughput trend, the %CPU use trend and the context switch rate trend. More information would be useful but the test is validated by the evidence that it is held up by lock contention. Er ... *what* evidence? There might be evidence somewhere that proves that, but Jignesh hasn't shown it. The available data suggests that the first-order performance limiter in this test is something else. Otherwise it should be possible to max out the performance with a lot less than 1000 active backends. regards, tom lane