Re: [Xen-devel] [PATCH 2 of 2 RFC] xl: allow for moving the domain's memory when changing vcpu affinity

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

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)

Ian.



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