From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Snitzer Subject: Re: dm thin: optimize away writing all zeroes to unprovisioned blocks Date: Fri, 5 Dec 2014 13:33:42 -0500 Message-ID: <20141205183342.GA27397@redhat.com> References: <20141204153358.GA19315@redhat.com> <5481EB1C.4000202@kernel.dk> Reply-To: LVM2 development Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <5481EB1C.4000202@kernel.dk> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: lvm-devel-bounces@redhat.com Errors-To: lvm-devel-bounces@redhat.com To: Jens Axboe Cc: Eric Wheeler , dm-devel@redhat.com, ejt@redhat.com, LVM2 development List-Id: dm-devel.ids On Fri, Dec 05 2014 at 12:27pm -0500, Jens Axboe wrote: > On 12/04/2014 08:33 AM, Mike Snitzer wrote: > > > >Here is a revised patch that is more like I'd expect to land upstream. > >Jens are you OK with us adding bio_is_zero_filled to block/bio.c? If so > >should I split it out as a separate patch for you to pick up or just > >carry it as part of the patch that lands in linux-dm.git? > > Yeah I'm fine with adding that helper. Good to know, thanks. > I do wonder what the performance impact is on this for dm. Have you > tried a (worst case) test of writing blocks that are zero filled, but > with the last byte not being a zero? I haven't tested that yet, but I share your concern. Does fio offer the ability to slap down a specific pattern like this? If not is there a logical place to extend fio to enable this? -- lvm-devel mailing list lvm-devel@redhat.com https://www.redhat.com/mailman/listinfo/lvm-devel From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Snitzer Date: Fri, 5 Dec 2014 13:33:42 -0500 Subject: dm thin: optimize away writing all zeroes to unprovisioned blocks In-Reply-To: <5481EB1C.4000202@kernel.dk> References: <20141204153358.GA19315@redhat.com> <5481EB1C.4000202@kernel.dk> Message-ID: <20141205183342.GA27397@redhat.com> List-Id: To: lvm-devel@redhat.com MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit On Fri, Dec 05 2014 at 12:27pm -0500, Jens Axboe wrote: > On 12/04/2014 08:33 AM, Mike Snitzer wrote: > > > >Here is a revised patch that is more like I'd expect to land upstream. > >Jens are you OK with us adding bio_is_zero_filled to block/bio.c? If so > >should I split it out as a separate patch for you to pick up or just > >carry it as part of the patch that lands in linux-dm.git? > > Yeah I'm fine with adding that helper. Good to know, thanks. > I do wonder what the performance impact is on this for dm. Have you > tried a (worst case) test of writing blocks that are zero filled, but > with the last byte not being a zero? I haven't tested that yet, but I share your concern. Does fio offer the ability to slap down a specific pattern like this? If not is there a logical place to extend fio to enable this?