From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:59188) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Sfddu-0001ui-LQ for qemu-devel@nongnu.org; Fri, 15 Jun 2012 17:01:20 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Sfdds-00054F-F5 for qemu-devel@nongnu.org; Fri, 15 Jun 2012 17:01:18 -0400 Received: from e28smtp01.in.ibm.com ([122.248.162.1]:36784) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Sfddr-00053K-HT for qemu-devel@nongnu.org; Fri, 15 Jun 2012 17:01:16 -0400 Received: from /spool/local by e28smtp01.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Sat, 16 Jun 2012 02:31:09 +0530 Received: from d28av03.in.ibm.com (d28av03.in.ibm.com [9.184.220.65]) by d28relay03.in.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id q5FL13fC12779930 for ; Sat, 16 Jun 2012 02:31:04 +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 q5G2UJG0028501 for ; Sat, 16 Jun 2012 12:30:20 +1000 Message-ID: <4FDBA28D.5090802@linux.vnet.ibm.com> Date: Sat, 16 Jun 2012 02:31:01 +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> <4FDA2D57.8030504@linux.vnet.ibm.com> In-Reply-To: <4FDA2D57.8030504@linux.vnet.ibm.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: supriyak@linux.vnet.ibm.com Cc: Kevin Wolf , zhihuili@cn.ibm.com, Taisuke Yamada , Stefan Hajnoczi , jcody@redhat.com, qemu-devel@nongnu.org, Zhi Hui Li On 06/14/2012 11:58 PM, Supriya Kannery wrote: > 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 > > Jeff, bdrv_reopen v1 patchset posted. Title: "Dynamic host pagecache change and image file reopen". Thanks, Supriya