From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:55748) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SfEmw-0001ax-A3 for qemu-devel@nongnu.org; Thu, 14 Jun 2012 14:28:59 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1SfEmt-0002H4-2v for qemu-devel@nongnu.org; Thu, 14 Jun 2012 14:28:57 -0400 Received: from e28smtp07.in.ibm.com ([122.248.162.7]:58529) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SfEms-0002GX-5b for qemu-devel@nongnu.org; Thu, 14 Jun 2012 14:28:55 -0400 Received: from /spool/local by e28smtp07.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 14 Jun 2012 23:58:44 +0530 Received: from d28av03.in.ibm.com (d28av03.in.ibm.com [9.184.220.65]) by d28relay04.in.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id q5EISfer3998018 for ; Thu, 14 Jun 2012 23:58:41 +0530 Received: from d28av03.in.ibm.com (loopback [127.0.0.1]) by d28av03.in.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id q5ENvv36007640 for ; Fri, 15 Jun 2012 09:57:57 +1000 Message-ID: <4FDA2D57.8030504@linux.vnet.ibm.com> Date: Thu, 14 Jun 2012 23:58:39 +0530 From: Supriya Kannery MIME-Version: 1.0 References: <4FD0B759.8030002@redhat.com> <4FD1FBF1.10305@redhat.com> <4FD20D11.1080603@redhat.com> <4FD22422.1080301@redhat.com> <4FD23A73.8080502@redhat.com> <4FD5E97A.2010207@redhat.com> <4FD610B9.8070507@redhat.com> <4FD9F3E8.8080306@linux.vnet.ibm.com> <4FD9F52E.3050507@redhat.com> In-Reply-To: <4FD9F52E.3050507@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Subject: Re: [Qemu-devel] CoW image commit+shrink(= make_empty) support Reply-To: supriyak@linux.vnet.ibm.com List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: jcody@redhat.com Cc: Kevin Wolf , zhihuili@cn.ibm.com, Taisuke Yamada , Stefan Hajnoczi , qemu-devel@nongnu.org, Zhi Hui Li On 06/14/2012 07:59 PM, Jeff Cody wrote: > On 06/14/2012 10:23 AM, Zhi Hui Li wrote: >> On 2012年06月11日 23:37, Jeff Cody wrote: >>> On 06/11/2012 10:24 AM, Stefan Hajnoczi wrote: >>>> On Mon, Jun 11, 2012 at 1:50 PM, Kevin Wolf wrote: >>>>> Am 11.06.2012 14:09, schrieb Stefan Hajnoczi: >>>>>> On Fri, Jun 8, 2012 at 6:46 PM, Jeff Cody wrote: >>>>>>> On 06/08/2012 12:11 PM, Kevin Wolf wrote: >>>>>>>> Am 08.06.2012 16:32, schrieb Jeff Cody: >>>>>>>>> On 06/08/2012 09:53 AM, Stefan Hajnoczi wrote: >>>>>>>>>> On Fri, Jun 8, 2012 at 2:19 PM, Jeff Cody wrote: >>>>>>>>>>> On 06/08/2012 08:42 AM, Stefan Hajnoczi wrote: >>>>>>>>>>>> Let's figure out how to specify block-commit so we're all happy, that >>>>>>>>>>>> way we can avoid duplicating work. Any comments on my notes above? >>>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> I think we are almost completely on the same page - devil is in the >>>>>>>>>>> details, of course (for instance, on how to convert the destination base >>>>>>>>>>> from r/o to r/w). >>>>>>>>>> >>>>>>>>>> Great. The atomic r/o -> r/w transition and the commit coroutine can >>>>>>>>>> be implemented on in parallel. Are you happy to implement the atomic >>>>>>>>>> r/o -> r/w transition since you wrote bdrv_append()? Then Zhi Hui can >>>>>>>>>> assume that part already works and focus on implementing the commit >>>>>>>>>> coroutine in the meantime. I'm just suggesting a way to split up the >>>>>>>>>> work, please let me know if you think this is good. >>>>>>>>> >>>>>>>>> I am happy to do it that way. I'll shift my focus to the atomic image >>>>>>>>> reopen in r/w mode. I'll go ahead and post my diagrams and other info >>>>>>>>> for block-commit on the wiki, because I don't think it conflicts with we >>>>>>>>> discussed above (although I will modify my diagrams to not show commit >>>>>>>>> from the top-level image). Of course, feel free to change it as >>>>>>>>> necessary. >>>>>>>> >>>>>>>> I may have mentioned it before, but just in case: I think Supriya's >>>>>>>> bdrv_reopen() patches are a good starting point. I don't know why they >>>>>>>> were never completed, but I think we all agreed on the general design, >>>>>>>> so it should be possible to pick that up. >>>>>>>> >>>>>>>> Though if you have already started with your own work on it, Jeff, I >>>>>>>> expect that it won't be much different because it's basically the same >>>>>>>> transactional approach that you know and that we already used for group >>>>>>>> snapshots. >>>>>>>> >>>>>>> >>>>>>> I will definitely use parts of Supriya's as it makes sense - what I >>>>>>> started work on is similar to bdrv_append() and the current transaction >>>>>>> approach, so there will be plenty in common to reuse, even with some >>>>>>> differences. >>>>>> >>>>>> I have CCed Supriya who has been working on the reopen patch series. >>>>>> She is close to posting a new version. >>>>> >>>>> It's just a bit disappointing that it takes several months between each >>>>> two versions of the patch series. We'd like to have this in qemu 1.2, >>>>> not only in qemu 1.14. >>>>> >>>>> I can understand if someone can't find the time, but then allow at least >>>>> someone else to pick it up. >>>> >>>> Hey, don't shoot the messenger :). I just wanted add Supriya to CC so >>>> she can join the discussion and see how much overlap there is with >>>> what she's doing. We all contribute to QEMU from different angles and >>>> with different priorities. If there is a time critical dependency on >>>> the reopen code then discuss it here and the result will be that >>>> someone officially drives the feature on. >>>> >>> >>> I am more than happy to take the previous reopen() patches, and drive >>> those forward, and also do whatever else is needed for live block >>> commit. >>> >>> It sounds like Zhi Hui is working on live block commit patches, and >>> Supriya is working on the bdrv_reopen() portion - I don't want to >>> duplicate any effort, but if there is anything I can do to help with >>> either of those areas, just let me know. >>> >>> Thanks, >>> Jeff >>> >>> >>> >> Jeff please go ahead with block-commit, I >> am finishing up my fdc async conversion patch series first. I will >> reply when I'm ready to work on block-commit. >> >> Thank you very much! >> > > Hi Zhi, > > I will do that. Thanks! > > Jeff > Jeff, Need another day's time for posting bdrv_reopen() patchset. Getting few hmp related build errors in hostcache toggling code when built on latest git. Will correct those and post the patchset soon. - Supriya