Hi -- According to the Xen Roadmap for 2006, there was talk of copy-on-write functionality that could be developed easily from the save/restore/migration code to enable features such as fast checkpoints or even VM forks. Has there been any progress on such work? Our research work would be highly interested in something to this effect, and could contribute to the effort if it''s still in progress. Thanks, Mike Sun Xen Roadmap 2006 "The save/restore/relocate in Xen provides almost all we need to be able to take copy-on-write snapshots of VM''s memory, to be used for rollback or to checkpoint long running jobs (if the guest is communicating with other machines then the wider effect of such a rollback must be considered). To be able to support checkpoints, we need to extend the tools to coordinate snapshotting of virtual disks with taking the execution state snapshot. As well as enabling such checkpoints to be initiated from the control tools, perhaps providing the ability to trigger them from within the guest would be useful too. A natural progression from supporting checkpointing would be to enable "VM forking". Rather than creating a read-only checkpoint, the VM effectively becomes cloned, running in a different domain, writing to a CoW snapshot of the disk." _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
At 14:59 -0500 on 05 Dec (1196866790), Mike Sun wrote:> According to the Xen Roadmap for 2006, there was talk of copy-on-write > functionality that could be developed easily from the > save/restore/migration code to enable features such as fast > checkpoints or even VM forks.FSVO "easily". :) I am working on extending the typed P2M work I did a while ago to allow pages to be marked copy-on-write, and other similar memory tricks. It''s still in the planning stage, but I hope to have some patches for comment fairly soon. Brendan Cully gave a talk on this area at the last Summit, and I know there is more work going on at UBC too. Tim -- Tim Deegan <Tim.Deegan@citrix.com> Principal Software Engineer, Citrix Systems. [Company #5334508: XenSource UK Ltd, reg''d c/o EC2Y 5EB, UK.] _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
hi I am interested in the COW VM memory ,and are there some code or patch about it ,or still in process ,or in plan? and if it has been implemented and integrated in the source tree, then ,what is the way to use it ? say , fast checkpoint, or VM fork ?or something else? is it available to use ? or how to do it ? Thanks Tim Deegan 写道:> At 14:59 -0500 on 05 Dec (1196866790), Mike Sun wrote: > >> According to the Xen Roadmap for 2006, there was talk of copy-on-write >> functionality that could be developed easily from the >> save/restore/migration code to enable features such as fast >> checkpoints or even VM forks. >> > > FSVO "easily". :) I am working on extending the typed P2M work I did a > while ago to allow pages to be marked copy-on-write, and other similar > memory tricks. It''s still in the planning stage, but I hope to have > some patches for comment fairly soon. > > Brendan Cully gave a talk on this area at the last Summit, and I know > there is more work going on at UBC too. > > Tim > >_______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Hi -- I'm currently in the process of implementing the COW functionality. It will probably take me some time, but I'll get back to you when I have a better idea of what the timeline will be. Mike On Jan 15, 2008 10:23 PM, tgh <wwwwww4187@sina.com.cn> wrote:> hi > I am interested in the COW VM memory ,and are there some code or patch > about it ,or still in process ,or in plan? and if it has been > implemented and integrated in the source tree, then ,what is the way to > use it ? say , fast checkpoint, or VM fork ?or something else? is it > available to use ? or how to do it ? > > Thanks > > > > > Tim Deegan 写道: > > > At 14:59 -0500 on 05 Dec (1196866790), Mike Sun wrote: > > > >> According to the Xen Roadmap for 2006, there was talk of copy-on-write > >> functionality that could be developed easily from the > >> save/restore/migration code to enable features such as fast > >> checkpoints or even VM forks. > >> > > > > FSVO "easily". :) I am working on extending the typed P2M work I did a > > while ago to allow pages to be marked copy-on-write, and other similar > > memory tricks. It's still in the planning stage, but I hope to have > > some patches for comment fairly soon. > > > > Brendan Cully gave a talk on this area at the last Summit, and I know > > there is more work going on at UBC too. > > > > Tim_______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Hi -- I'm attempting to implement some sort of COW functionality for use in fast snapshotting, but have a few questions I'm hoping people can help out with. As per typical OS COW implementations, I mark the memory pages I want COW to read only protection. When I receive the page protection fault in the hypervisor page fault handler, is there a way for me to determine if the protection fault is the result my my COW action as opposed to a protection fault actually incurred by the guest (i.e. perhaps the guest OS is implementing its own COW on portions of its memory)? The only method I can think of is to keep track of the protection bits of the pages before I have the hypervisor modify them to read only, and use this information in the hypervisor's page fault handler to determine what it should reset the page's protection bits to be after the page has been copied. Thanks, Mike 2008/1/15 Mike Sun <msun@gatech.edu>:> Hi -- > > I'm currently in the process of implementing the COW functionality. > It will probably take me some time, but I'll get back to you when I > have a better idea of what the timeline will be. > > Mike > > > On Jan 15, 2008 10:23 PM, tgh <wwwwww4187@sina.com.cn> wrote: > > hi > > I am interested in the COW VM memory ,and are there some code or patch > > about it ,or still in process ,or in plan? and if it has been > > implemented and integrated in the source tree, then ,what is the way to > > use it ? say , fast checkpoint, or VM fork ?or something else? is it > > available to use ? or how to do it ? > > > > Thanks > > > > > > > > > > Tim Deegan 写道: > > > > > At 14:59 -0500 on 05 Dec (1196866790), Mike Sun wrote: > > > > > >> According to the Xen Roadmap for 2006, there was talk of copy-on-write > > >> functionality that could be developed easily from the > > >> save/restore/migration code to enable features such as fast > > >> checkpoints or even VM forks. > > >> > > > > > > FSVO "easily". :) I am working on extending the typed P2M work I did a > > > while ago to allow pages to be marked copy-on-write, and other similar > > > memory tricks. It's still in the planning stage, but I hope to have > > > some patches for comment fairly soon. > > > > > > Brendan Cully gave a talk on this area at the last Summit, and I know > > > there is more work going on at UBC too. > > > > > > Tim >_______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Mike Sun, le Mon 04 Feb 2008 22:14:26 -0500, a écrit :> is there a way for me to determine if the protection fault is the > result my my COW action as opposed to a protection fault actually > incurred by the guest (i.e. perhaps the guest OS is implementing its > own COW on portions of its memory)?Not that I''m aware of.> The only method I can think of is to keep track of the > protection bits of the pages before I have the hypervisor modify them > to read only,Yes. Samuel _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel