From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jens Axboe Subject: Re: [PATCH] dm thin: optimize away writing all zeroes to unprovisioned blocks Date: Fri, 05 Dec 2014 10:27:56 -0700 Message-ID: <5481EB1C.4000202@kernel.dk> References: <20141204153358.GA19315@redhat.com> Reply-To: device-mapper development Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20141204153358.GA19315@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com To: Mike Snitzer , Eric Wheeler Cc: dm-devel@redhat.com, ejt@redhat.com, LVM2 development List-Id: dm-devel.ids 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. 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? -- Jens Axboe From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jens Axboe Date: Fri, 05 Dec 2014 10:27:56 -0700 Subject: [PATCH] dm thin: optimize away writing all zeroes to unprovisioned blocks In-Reply-To: <20141204153358.GA19315@redhat.com> References: <20141204153358.GA19315@redhat.com> Message-ID: <5481EB1C.4000202@kernel.dk> List-Id: To: lvm-devel@redhat.com MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit 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. 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? -- Jens Axboe