Re: [Xen-devel] [PATCH] (resent) NUMA node migration

Mark Williamson
Sun, 23 Dec 2007 21:12:02 -0000

> for PV, is there a fast checkpoint mechanism available ? how does it
> work , that is ,what paremeters in the common line"xm migration
",or how
> to invoke it?

xm save -c does a checkpoint

The "Checkpoint" operation means that the guest is resumed immediately
after
the save has completed, rather than being stopped or migrated.

> and how does it work ,say ,fast checkpoint for PV in an
> incremental way such as live migration, or how to fast checkpoint ?

It''s not an incremental process in the case of a checkpoint: at the
moment it
still stops the guests execution for the period of the save - just like
normal xm save does.

After the save continues, the guest is instructed to resume its own execution.

Cheers,
Mark

>
> Thanks in advance
>
> Ian Pratt 写道:
> > Doing page migration for HVM guests is easy as you can just stop the
> > guest, copy a bunch of pages and update the p2m table, flush the
shadow
> > page table cache and all VCPU''s TLBs, then resume. Doing it
live is a
> > little tricky as you have to go from MFN''s to PTE''s
which currently
> > requires a full shadow page table scan. [Though some of the
experimental
> > page sharing patches maintain linked lists of backpointers, and we
could
> > switch to a shadow mode that supports this while doing page migration]
> >
> > PV guests are a little more challenging as all references in the
> > direct-mode page tables need to be updated. We also need to make sure
> > that the guest isn''t holding MFNs outside of pagetables, so
we need to
> > get all the VCPUs into a known state. The best way of handling this is
> > to use the PV fast checkpoint support to freeze the guest, copy the
> >
> >
> > badly located pages, scan and update all pagetables, resume from
> > checkpoint. This would make a nice little project for someone...
> >
> > Ian
> >
> >
> >
> > _______________________________________________
> > Xen-devel mailing list
> > Xen-devel@lists.xensource.com
> > http://lists.xensource.com/xen-devel
>
> _______________________________________________
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> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel



--
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