> > > * Liang Li (liang.z...@intel.com) wrote: > > > > The current QEMU live migration implementation mark the all the > > > > guest's RAM pages as dirtied in the ram bulk stage, all these > > > > pages will be processed and that takes quit a lot of CPU cycles. > > > > > > > > From guest's point of view, it doesn't care about the content in > > > > free pages. We can make use of this fact and skip processing the > > > > free pages in the ram bulk stage, it can save a lot CPU cycles and > > > > reduce the network traffic significantly while speed up the live > > > > migration process obviously. > > > > > > > > This patch set is the QEMU side implementation. > > > > > > > > The virtio-balloon is extended so that QEMU can get the free pages > > > > information from the guest through virtio. > > > > > > > > After getting the free pages information (a bitmap), QEMU can use > > > > it to filter out the guest's free pages in the ram bulk stage. > > > > This make the live migration process much more efficient. > > > > > > Hi, > > > An interesting solution; I know a few different people have been > > > looking at how to speed up ballooned VM migration. > > > > > > > Ooh, different solutions for the same purpose, and both based on the > balloon. > > We were also tying to address similar problem, without actually needing to > modify the guest driver. Please find patch details under mail with subject. > migration: skip sending ram pages released by virtio-balloon driver > > Thanks, > - Jitendra >
Great! Thanks for your information. Liang > > > > > I wonder if it would be possible to avoid the kernel changes by > > > parsing /proc/self/pagemap - if that can be used to detect > > > unmapped/zero mapped pages in the guest ram, would it achieve the > same result? > > >
