Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753787Ab0HWOMu (ORCPT ); Mon, 23 Aug 2010 10:12:50 -0400 Received: from hera.kernel.org ([140.211.167.34]:59855 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752708Ab0HWOMq (ORCPT ); Mon, 23 Aug 2010 10:12:46 -0400 Message-ID: <4C728210.6040605@kernel.org> Date: Mon, 23 Aug 2010 16:13:36 +0200 From: Tejun Heo User-Agent: Mozilla/5.0 (X11; U; Linux i686 (x86_64); en-US; rv:1.9.2.8) Gecko/20100802 Thunderbird/3.1.2 MIME-Version: 1.0 To: Christoph Hellwig CC: Jens Axboe , Ric Wheeler , "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 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> <20100823140823.GA23490@lst.de> In-Reply-To: <20100823140823.GA23490@lst.de> X-Enigmail-Version: 1.1.1 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.3 (hera.kernel.org [127.0.0.1]); Mon, 23 Aug 2010 14:12:22 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1211 Lines: 30 Hello, On 08/23/2010 04:08 PM, Christoph Hellwig wrote: > 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. Yeah, that sounds reasonable. blk_queue_flush() can be called anytime without locking anyway, so it should be really easy to implement too. Thanks. -- tejun -- 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/