X-Original-To: pgsql-hackers-postgresql.org@localhost.postgresql.org Received: from localhost (av.hub.org [200.46.204.144]) by postgresql.org (Postfix) with ESMTP id 1D5149DCAB2 for ; Tue, 29 Nov 2005 00:14:54 -0400 (AST) Received: from postgresql.org ([200.46.204.71]) by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) with ESMTP id 03800-10 for ; Tue, 29 Nov 2005 00:14:51 -0400 (AST) X-Greylist: from auto-whitelisted by SQLgrey- Received: from linuxworld.com.au (unknown [203.34.46.50]) by postgresql.org (Postfix) with ESMTP id 077CC9DCAB3 for ; Tue, 29 Nov 2005 00:14:50 -0400 (AST) Received: from linuxworld.com.au (IDENT:swm@localhost.localdomain [127.0.0.1]) by linuxworld.com.au (8.13.2/8.13.2) with ESMTP id jAT4EcqF018375; Tue, 29 Nov 2005 15:14:38 +1100 Received: from localhost (swm@localhost) by linuxworld.com.au (8.13.2/8.13.2/Submit) with ESMTP id jAT4EcJH018372; Tue, 29 Nov 2005 15:14:38 +1100 Date: Tue, 29 Nov 2005 15:14:38 +1100 (EST) From: Gavin Sherry To: David Boreham cc: pgsql-hackers@postgresql.org Subject: Re: ice-broker scan thread In-Reply-To: <438BD493.3070507@boreham.org> Message-ID: References: <438BD493.3070507@boreham.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Virus-Scanned: by amavisd-new at hub.org X-Spam-Status: No, score=0 required=5 tests=[none] X-Spam-Score: 0 X-Spam-Level: X-Archive-Number: 200511/1453 X-Sequence-Number: 76735 On Mon, 28 Nov 2005, David Boreham wrote: > Gavin Sherry wrote: > > > MySQL, Oracle and others implement read-ahead threads to simulate async IO > > I always believed that Oracle used async file I/O. Not that I've seen their > code, but I'm fairly sure they funded the addition of kernel aio to Linux > a few years back. That's right. > > But....Oracle comes from a time long ago when threads and decent > filesystems didn't exist, so some of the things they do may not be > appropriate > to add to a product that doesn't have them today. The paper I linked to seemed to suggest that they weren't using async IO in 9.2 -- which is fairly old. I'm not sure why the authors didn't test 10g. Gavin