From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jens Axboe Subject: Re: [PATCHSET block#for-2.6.36-post] block: replace barrier with sequenced flush Date: Wed, 25 Aug 2010 13:31:49 +0200 Message-ID: <4C74FF25.3060200@fusionio.com> 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> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20100823140823.GA23490@lst.de> Sender: linux-raid-owner@vger.kernel.org To: Christoph Hellwig Cc: Ric Wheeler , 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" List-Id: linux-raid.ids On 2010-08-23 16:08, 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. Agree, that would be fine. -- Jens Axboe