From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761277AbYD3KiZ (ORCPT ); Wed, 30 Apr 2008 06:38:25 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755766AbYD3KiQ (ORCPT ); Wed, 30 Apr 2008 06:38:16 -0400 Received: from mx1.redhat.com ([66.187.233.31]:57137 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755247AbYD3KiP (ORCPT ); Wed, 30 Apr 2008 06:38:15 -0400 Date: Wed, 30 Apr 2008 11:38:00 +0100 From: Alasdair G Kergon To: Jens Axboe Cc: Mike Anderson , Mikulas Patocka , linux-kernel@vger.kernel.org Subject: Re: [PATCH] Optimize lock in queue unplugging Message-ID: <20080430103759.GM18935@agk.fab.redhat.com> Mail-Followup-To: Alasdair G Kergon , Jens Axboe , Mike Anderson , Mikulas Patocka , linux-kernel@vger.kernel.org References: <20080429192556.GB12774@kernel.dk> <20080429202928.GB10641@linux.vnet.ibm.com> <20080430071415.GM12774@kernel.dk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080430071415.GM12774@kernel.dk> User-Agent: Mutt/1.4.1i Organization: Red Hat UK Ltd. Registered in England and Wales, number 03798903. Registered Office: Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SL4 1TE. Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Apr 30, 2008 at 09:14:15AM +0200, Jens Axboe wrote: > So it's basically dm calling into blk_unplug() all the time, which > doesn't check if the queue is plugged. The reason why I didn't like the > initial patch is that ->unplug_fn() really should not be called unless > the queue IS plugged. So how about this instead: > > http://git.kernel.dk/?p=linux-2.6-block.git;a=commit;h=c44993018887e82abd49023e92e8d8b6000e03ed > > That's a lot more appropriate, imho. Makes sense to me, ack. Alasdair -- agk@redhat.com