[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH 2 of 2 RFC] xl: allow for moving the domain's memory when changing vcpu affinity
On Fri, 2012-07-06 at 14:30 +0100, George Dunlap wrote: > On 06/07/12 14:25, Ian Campbell wrote: > > On Fri, 2012-07-06 at 13:53 +0100, George Dunlap wrote: > >> On 06/07/12 10:54, Dario Faggioli wrote: > >>> By introducing a new '-M' option to the `xl vcpu-pin' command. The actual > >>> memory "movement" is achieved suspending the domain to a ttemporary file > >>> and > >>> resuming it with the new vcpu-affinity > >> Hmm... this will work and be reliable, but it seems a bit clunky. Long > >> term we want to be able to do node migration in the background without > >> shutting down a VM, right? If that can be done in the 4.3 timeframe, > >> then it seems unnecessary to implement something like this. > > We could do something cleverer for HVM (or hybrid) guests to migrate > > pages while the guest is live but migrating a page under a PV guest's > > feet requires quiescing it in the style of a migrate. > > > > We could probably manage to make it such that you just need the > > pause/frob/unpause phases without actually writing RAM to disk, and that > > infrastructure might be useful for other reasons I suppose. (e.g. I > > think bad page offlining currently uses a similar save/restore trick) > Yes, I think doing this chunks at a time is likely to be much > preferrable to writing the whole thing to disk and reading it out > again. Doing it "live" may end up with more total overhead, but it > wont' require the VM being actually down for the suspend/resume cycle, > which on a large guest may be tens of seconds. Tim also suggested a PV protocol whereby the tools hint to the guest "if you XENMEM_exchange this MFN you will get back an MFN which is much better for your performance". (at least I think that's what Tim suggested, I may have misunderstood) Ian. _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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