From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:38510) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bpAJx-00072n-0U for qemu-devel@nongnu.org; Wed, 28 Sep 2016 04:34:29 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bpAJv-0007iP-Si for qemu-devel@nongnu.org; Wed, 28 Sep 2016 04:34:28 -0400 Date: Wed, 28 Sep 2016 10:34:15 +0200 From: Kevin Wolf Message-ID: <20160928083415.GC5236@noname.redhat.com> References: <1474893981-5302-1-git-send-email-vsementsov@virtuozzo.com> <27bd2bc9-b879-81ef-c7b6-31335e6be84f@virtuozzo.com> <912490881.3041685.1474971311025.JavaMail.zimbra@redhat.com> <61b997ac-f9b9-37a2-6a0b-412ad77ddedd@virtuozzo.com> <2133222015.3059876.1474978044995.JavaMail.zimbra@redhat.com> <2c6d5867-3f0b-3ae6-3d3c-7b515243f39a@virtuozzo.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Subject: Re: [Qemu-devel] [PATCH] proto: add 'shift' extension. List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Denis V. Lunev" Cc: Paolo Bonzini , Vladimir Sementsov-Ogievskiy , qemu-devel@nongnu.org, qemu-block@nongnu.org, nbd-general@lists.sourceforge.net, alex@alex.org.uk, eblake@redhat.com, stefanha@redhat.com, w@uter.be Am 27.09.2016 um 20:59 hat Denis V. Lunev geschrieben: > On 09/27/2016 08:04 PM, Paolo Bonzini wrote: > > > > On 27/09/2016 15:28, Denis V. Lunev wrote: > >> On 09/27/2016 03:07 PM, Paolo Bonzini wrote: > >>> ----- Original Message ----- > >>>> From: "Denis V. Lunev" > >>>> To: "Paolo Bonzini" > >>>> Cc: "Vladimir Sementsov-Ogievskiy" , qemu-devel@nongnu.org, qemu-block@nongnu.org, > >>>> nbd-general@lists.sourceforge.net, alex@alex.org.uk, eblake@redhat.com, kwolf@redhat.com, stefanha@redhat.com, > >>>> w@uter.be > >>>> Sent: Tuesday, September 27, 2016 12:25:54 PM > >>>> Subject: Re: [PATCH] proto: add 'shift' extension. > >>>> > >>>> On 09/27/2016 01:15 PM, Paolo Bonzini wrote: > >>>>>> We could go in a different direction and export flag > >>>>>> 'has_zero_init' which will report that the storage is > >>>>>> initialized with all zeroes at the moment. In this > >>>>>> case mirroring code will not fall into this > >>>>>> branch. > >>>>> Why don't you add the zero_init flag to QEMU's NBD driver instead? > >>>> for all cases without knowing real backend on the server side? > >>>> I think this would be wrong. > >>> Add it to the command line, and leave it to libvirt or the user to > >>> pass "-drive file.driver=nbd,...,file.zero-init=on". > >> I have started with something very similar for 'drive-mirror' command. > >> We have added additional flag for this to improve migration speed > >> and this was rejected. > > You can add it through the filename path too, through a URI option > > "nbd://...?zero-init=on". > > > > Paolo > ha, cool idea! Thanks! What's the advantage of writing "?zero-init=on" instead of ",zero-init=on"? Doesn't it only add more string parsing code for no benefit? Kevin