Messages in this thread | | | From | "Li, Liang Z" <> | Subject | RE: [Qemu-devel] [RFC qemu 0/4] A PV solution for live migration optimization | Date | Fri, 4 Mar 2016 10:11:00 +0000 |
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> On Fri, Mar 04, 2016 at 09:12:12AM +0000, Li, Liang Z wrote: > > > Although I wonder which is cheaper; that would be fairly expensive > > > for the guest wouldn't it? And you'd somehow have to kick the guest > > > before migration to do the ballooning - and how long would you wait for > it to finish? > > > > About 5 seconds for an 8G guest, balloon to 1G. Get the free pages > > bitmap take about 20ms for an 8G idle guest. > > > > Liang > > Where is the time spent though? allocating within guest? > Or passing the info to host? > If the former, we can use existing inflate/deflate vqs: > Have guest put each free page on inflate vq, then on deflate vq. >
Maybe I am not clear enough.
I mean if we inflate balloon before live migration, for a 8GB guest, it takes about 5 Seconds for the inflating operation to finish.
For the PV solution, there is no need to inflate balloon before live migration, the only cost is to traversing the free_list to construct the free pages bitmap, and it takes about 20ms for a 8GB idle guest( less if there is less free pages), passing the free pages info to host will take about extra 3ms.
Liang > -- > MST
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