Received: from localhost (unknown [200.46.204.187]) by postgresql.org (Postfix) with ESMTP id D70022E2DB2 for ; Mon, 21 Jan 2008 20:46:08 -0400 (AST) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.187]) (amavisd-maia, port 10024) with ESMTP id 63662-04 for ; Mon, 21 Jan 2008 20:45:55 -0400 (AST) Received: from mail.midstorm.org (mail.midstorm.org [65.99.212.143]) by postgresql.org (Postfix) with ESMTP id 1DD552E0261 for ; Mon, 21 Jan 2008 20:46:00 -0400 (AST) Received: from pmanson (201-67-30-77.bsace703.dsl.brasiltelecom.net.br [201.67.30.77]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mail.midstorm.org (Postfix) with ESMTP id 61631403BB for ; Mon, 21 Jan 2008 22:45:57 -0200 (BRST) Date: Mon, 21 Jan 2008 22:48:21 -0200 From: Fernando Ike To: pgsql-performance@postgresql.org Subject: Re: 8.3 synchronous_commit Message-ID: <20080121224821.22c2a800@pmanson> In-Reply-To: <1200959154.10057.533.camel@dogma.ljc.laika.com> References: <1200959154.10057.533.camel@dogma.ljc.laika.com> X-Mailer: Claws Mail 3.2.0 (GTK+ 2.12.5; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200801/169 X-Sequence-Number: 28408 Em Mon, 21 Jan 2008 15:45:54 -0800 Jeff Davis escreveu: > On Mon, 2008-01-21 at 18:31 -0500, Greg Smith wrote: > > pgbench doesn't handle 100 clients at once very well on the same > > box as the server, unless you have a pretty serious system. The > > pgbench program itself has a single process model that doesn't > > handle the CFQ round-robin very well at all. On top of that, the > > database scale should be bigger > > He was referring to the CFQ I/O scheduler. I don't think that will > affect pgbench itself, because it doesn't read/write to disk, right? > No. But pgbench local running, it will be concurrency with PostgreSQL. I'm realized some test and really confirm disable *synchronous_commit* performance degrade with CFQ and Deadline. Kind Regards, -- Fernando Ike http://www.midstorm.org/~fike/weblog