Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753526Ab0HWOIx (ORCPT ); Mon, 23 Aug 2010 10:08:53 -0400 Received: from verein.lst.de ([213.95.11.210]:40144 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751861Ab0HWOIw (ORCPT ); Mon, 23 Aug 2010 10:08:52 -0400 Date: Mon, 23 Aug 2010 16:08:23 +0200 From: Christoph Hellwig To: Jens Axboe Cc: Ric Wheeler , Christoph Hellwig , Tejun Heo , "linux-fsdevel@vger.kernel.org" , "linux-scsi@vger.kernel.org" , "linux-ide@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-raid@vger.kernel.org" , "James.Bottomley@suse.de" , "tytso@mit.edu" , "chris.mason@oracle.com" , "swhiteho@redhat.com" , "konishi.ryusuke@lab.ntt.co.jp" , "dm-devel@redhat.com" , "vst@vlnb.net" , "jack@suse.cz" , "hare@suse.de" Subject: Re: [PATCHSET block#for-2.6.36-post] block: replace barrier with sequenced flush Message-ID: <20100823140823.GA23490@lst.de> References: <1281616891-5691-1-git-send-email-tj@kernel.org> <20100820132214.GA6184@lst.de> <4C6E9CAF.5010202@redhat.com> <4C7269E9.9070304@kernel.org> <20100823124815.GA20095@lst.de> <4C727E96.5020801@redhat.com> <4C727F2B.6060501@fusionio.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4C727F2B.6060501@fusionio.com> User-Agent: Mutt/1.3.28i X-Spam-Score: 0 () Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 967 Lines: 19 On Mon, Aug 23, 2010 at 04:01:15PM +0200, Jens Axboe wrote: > The problem purely exists on arrays that report write back cache enabled > AND don't implement SYNC_CACHE as a noop. Do any of them exist, or are > they purely urban legend? I haven't seen it. I don't care particularly about this case, but once it a while people want to disable flushing for testing or because they really don't care. What about adding a sysfs attribue to every request_queue that allows disabling the cache flushing feature? Compared to the barrier option this controls the feature at the right level and makes it available to everyone instead of beeing duplicated. After a while we can then simply ignore the barrier/nobarrier options. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/