From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: [RFC] relaxed barrier semantics Date: Fri, 30 Jul 2010 15:07:25 +0200 Message-ID: <4C52CE8D.4020209@kernel.org> References: <20100728085048.GA8884@lst.de> <4C4FF136.5000205@kernel.org> <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> <25F5E16E-968D-4FEF-8187-70453985B19B@dilger.ca> <20100729230406.GI4506@thunk.org> <4C52CBFF.6090406@vlnb.net> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: "Ted Ts'o" , Andreas Dilger , Ric Wheeler , Christoph Hellwig , Vivek Goyal , Jan Kara , jaxboe@fusionio.com, James.Bottomley@suse.de, linux-fsdevel@vger.kernel.org, linux-scsi@vger.kernel.org, chris.mason@oracle.com, swhiteho@redhat.com, konishi.ryusuke@lab.ntt.co.jp To: Vladislav Bolkhovitin Return-path: In-Reply-To: <4C52CBFF.6090406@vlnb.net> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On 07/30/2010 02:56 PM, Vladislav Bolkhovitin wrote: > 1. 1st journal write command (SIMPLE) > > 2. 2d journal write command (SIMPLE) > > 3. 3d journal write command (SIMPLE) > > 4. SYNCHRONIZE_CACHE for blocks written by those 3 commands (ORDERED) > > 5. Necessary amount of meta-data update commands (all SIMPLE) > > 6. SYNCHRONIZE_CACHE for blocks written in 5 (ORDERED) > > 7. Command marking the transaction committed in the journal (ORDERED) > > That's all. No queue draining anywhere. Plus, sending commands > without internal order requirements as SIMPLE would allow the drive > to better schedule execution of them among internal storage (actual > disks). Are SIMPLE commands ordered against ORDERED commands? Aren't ORDERED ordered among themselves only? -- tejun