From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vladislav Bolkhovitin Subject: Re: [RFC] relaxed barrier semantics Date: Fri, 30 Jul 2010 17:09:52 +0400 Message-ID: <4C52CF20.6090404@vlnb.net> References: <20100728090025.GA9252@lst.de> <4C4FF592.9090800@kernel.org> <20100728092859.GA11096@lst.de> <20100729014431.GD4506@thunk.org> <4C51DA1F.2040701@redhat.com> <20100729194904.GA17098@lst.de> <4C51DCF1.3010507@redhat.com> <1280433591.4441.393.camel@mulgrave.site> <20100729200327.GA17767@lst.de> <4C52C994.2040405@vlnb.net> <20100730125750.GB26118@lst.de> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: James Bottomley , Ric Wheeler , Ted Ts'o , Tejun Heo , Vivek Goyal , Jan Kara , jaxboe@fusionio.com, linux-fsdevel@vger.kernel.org, linux-scsi@vger.kernel.org, chris.mason@oracle.com, swhiteho@redhat.com, konishi.ryusuke@lab.ntt.co.jp To: Christoph Hellwig Return-path: Received: from moutng.kundenserver.de ([212.227.17.10]:65196 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756650Ab0G3NJu (ORCPT ); Fri, 30 Jul 2010 09:09:50 -0400 In-Reply-To: <20100730125750.GB26118@lst.de> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: Christoph Hellwig, on 07/30/2010 04:57 PM wrote: > On Fri, Jul 30, 2010 at 04:46:12PM +0400, Vladislav Bolkhovitin wrote: >> I supposed, with write back cache you did the queue drain after >> request(s) with ordered requirements, correct? Did you also do the queue >> drain in the same places with write through caching? > > Using the queue drains in both cases. I can only imagine keeping the > queue drained over the cache flush instead of just a few small I/Os > has nasty side effects. Sorry, I can't follow you here. What was the load pattern difference between the tests in the way how the backend device saw it? I thought, it was only in absence of the cache flush commands (SYNCHRONIZE_CACHE?) in the write through case, but looks like there is something more different? Thanks, Vlad