Received: from localhost (unknown [200.46.204.183]) by mail.postgresql.org (Postfix) with ESMTP id 22E496501DC for ; Wed, 26 Nov 2008 19:09:27 -0400 (AST) Received: from mail.postgresql.org ([200.46.204.86]) by localhost (mx1.hub.org [200.46.204.183]) (amavisd-maia, port 10024) with ESMTP id 86967-06 for ; Wed, 26 Nov 2008 19:09:24 -0400 (AST) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from gwmta.wicourts.gov (gwmta.wicourts.gov [165.219.244.99]) by mail.postgresql.org (Postfix) with ESMTP id 6FC9E65014C for ; Wed, 26 Nov 2008 19:09:24 -0400 (AST) Received: from Courts-MTA by gwmta.wicourts.gov with Novell_GroupWise; Wed, 26 Nov 2008 17:09:23 -0600 Message-Id: <492D82BB.EE98.0025.0@wicourts.gov> X-Mailer: Novell GroupWise Internet Agent 7.0.3 Date: Wed, 26 Nov 2008 17:09:15 -0600 From: "Kevin Grittner" To: "Ryan Hansen" , "pgsql-performance@postgresql.org" , "Scott Carey" Subject: Re: Memory Allocation References: <011101c95013$b6fca0a0$24f5e1e0$@hansen@brightbuilders.com> In-Reply-To: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Content-Disposition: inline X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200811/277 X-Sequence-Number: 32008 >>> Scott Carey wrote: > Set swappiness to 0 or 1. We recently converted all 72 remote county databases from 8.2.5 to 8.3.4. In preparation we ran a test conversion of a large county over and over with different settings to see what got us the best performance. Setting swappiness below the default degraded performance for us in those tests for identical data, same hardware, no other changes. Our best guess is that code which really wasn't getting called got swapped out leaving more space in the OS cache, but that's just a guess. Of course, I'm sure people would not be recommending it if they hadn't done their own benchmarks to confirm that this setting actually improved things in their environments, so the lesson here is to test for your environment when possible. -Kevin