From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hannes Reinecke Subject: Re: [PATCHSET block#for-2.6.36-post] block: replace barrier with sequenced flush Date: Mon, 30 Aug 2010 12:04:56 +0200 Message-ID: <4C7B8248.5070602@suse.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> <20100823140823.GA23490@lst.de> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <20100823140823.GA23490@lst.de> Sender: linux-ide-owner@vger.kernel.org To: Christoph Hellwig Cc: Jens Axboe , 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" List-Id: dm-devel.ids 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 ena= bled >> AND don't implement SYNC_CACHE as a noop. Do any of them exist, or a= re >> they purely urban legend? >=20 > I haven't seen it. I don't care particularly about this case, but on= ce > it a while people want to disable flushing for testing or because the= y > really don't care. >=20 aacraid for one falls into this category. SYNC_CACHE is no-oped in the driver. Otherwise you get a _HUGE_ performance loss. Cheers, Hannes --=20 Dr. Hannes Reinecke zSeries & Storage hare@suse.de +49 911 74053 688 SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 N=FCrnberg GF: Markus Rex, HRB 16746 (AG N=FCrnberg)