From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joe Thornber Subject: Re: [dm-devel] [PATCH] staging: writeboost: Add dm-writeboost Date: Wed, 10 Dec 2014 12:33:50 +0000 Message-ID: <20141210123349.GC21108@debian> References: <5484498E.4000202@gmail.com> <20141207200834.GA2322@kroah.com> <5484C0E9.3060707@gmail.com> <20141209151253.GA17660@debian> <20141210100033.GA21108@debian> <548827BD.3050803@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <548827BD.3050803@gmail.com> Sender: linux-kernel-owner@vger.kernel.org To: Akira Hayakawa Cc: ejt@redhat.com, dm-devel@redhat.com, gregkh@linuxfoundation.org, snitzer@redhat.com, agk@redhat.com, linux-kernel@vger.kernel.org List-Id: dm-devel.ids On Wed, Dec 10, 2014 at 08:00:13PM +0900, Akira Hayakawa wrote: > Hi, Joe > > Thanks for continuous evaluation. Some more details: dd, with block size 512b ------------------------ raw spindle : 143 writeboost Type 0: 137 writeboost Type 1: 130 dd, with block size 4k ---------------------- raw spindle : 31 writeboost Type 0: 29 writeboost Type 1: 81 dd, with block size 64m ----------------------- raw spindle : 8.9 writeboost Type 0: 32 writeboost Type 1: 72 So maybe it's just volume of IO that's causing the problem? What's the difference between Type 0 and Type 1? In the code I notice you have 'rambuf' structures, are you caching IO in memory?