From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: [PATCHSET block#for-2.6.36-post] block: replace barrier with sequenced flush Date: Fri, 13 Aug 2010 15:21:36 +0200 Message-ID: <4C6546E0.7070208@kernel.org> References: <1281616891-5691-1-git-send-email-tj@kernel.org> <4C6540C5.8070108@vlnb.net> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4C6540C5.8070108@vlnb.net> Sender: linux-fsdevel-owner@vger.kernel.org To: Vladislav Bolkhovitin Cc: jaxboe@fusionio.com, 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, hch@lst.de, James.Bottomley@suse.de, tytso@mit.edu, chris.mason@oracle.com, swhiteho@redhat.com, konishi.ryusuke@lab.ntt.co.jp, dm-devel@redhat.com, jack@suse.cz, rwheeler@redhat.com, hare@suse.de List-Id: linux-raid.ids Hello, On 08/13/2010 02:55 PM, Vladislav Bolkhovitin wrote: > If requested, I can develop the interface further. I still think the benefit of ordering by tag would be marginal at best, and what have you guys measured there? Under the current framework, there's no easy way to measure full ordered-by-tag implementation. The mechanism for filesystems to communicate the ordering information (which would be a partially ordered graph) just isn't there and there is no way the current usage of ordering-by-tag only for barrier sequence can achieve anything close to that level of difference. Ripping out the original ordering by tag mechanism doesn't amount to much. The use of ordering-by-tag was pretty half-assed there anyway. If you think exporting full ordering information from filesystem to the lower layers is worthwhile, please go ahead. It would be very interesting to see how much actual difference it can make compared to ordering-by-filesystem and if it's actually better and the added complexity is manageable, there's no reason not to do that. Thank you. -- tejun