From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [PATCHSET block#for-2.6.36-post] block: replace barrier with sequenced flush Date: Mon, 23 Aug 2010 16:08:23 +0200 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 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" To: Jens Axboe Return-path: 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 Content-Disposition: inline In-Reply-To: <4C727F2B.6060501@fusionio.com> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: 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.