From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vladislav Bolkhovitin Subject: Re: [RFC] relaxed barrier semantics Date: Thu, 05 Aug 2010 23:32:04 +0400 Message-ID: <4C5B11B4.9020807@vlnb.net> References: <4C4FE58C.8080403@kernel.org> <20100728082447.GA7668@lst.de> <4C4FECFE.9040509@kernel.org> <20100728085048.GA8884@lst.de> <4C4FF136.5000205@kernel.org> <20100728090025.GA9252@lst.de> <4C4FF592.9090800@kernel.org> <20100728092859.GA11096@lst.de> <20100802173930.GP16630@think> <4C5AB89C.5080700@vlnb.net> <20100805170933.GB10728@lst.de> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Chris Mason , Tejun Heo , Vivek Goyal , Jan Kara , jaxboe@fusionio.com, James.Bottomley@suse.de, linux-fsdevel@vger.kernel.org, linux-scsi@vger.kernel.org, tytso@mit.edu, swhiteho@redhat.com, konishi.ryusuke@lab.ntt.co.jp To: Christoph Hellwig Return-path: In-Reply-To: <20100805170933.GB10728@lst.de> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org Christoph Hellwig, on 08/05/2010 09:09 PM wrote: > On Thu, Aug 05, 2010 at 05:11:56PM +0400, Vladislav Bolkhovitin wrote: >> Chris Mason, on 08/02/2010 09:39 PM wrote: >>> I regret putting the ordering into the original barrier code...it >>> definitely did help reiserfs back in the day but it stinks of magic and >>> voodoo. >> >> But if the ordering isn't in the common (block) code, how to implement >> the "hardware offload" for ordering, i.e. ORDERED commands, in an >> acceptable way? > > Right now we have no working implementation of actually using ordered > tags for a storage device in Linux. There's very little need for common > code in that implementation - basically we just need flag in the bio / > request to make this one an ordered tag in addition to the existing > reordering preventing in the block queue. New flag.. Easy to add, hard to live with. Aren't you already tied of the existing flags hell? Vlad