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

[Mark Williamson <mark.williamson@xxxxxxxxxxxx>]

> 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 åé:
> > 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@xxxxxxxxxxxxxxxxxxx
> > http://lists.xensource.com/xen-devel
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-devel



-- 
Dave: Just a question. What use is a unicyle with no seat?  And no pedals!
Mark: To answer a question with a question: What use is a skateboard?
Dave: Skateboards have wheels.
Mark: My wheel has a wheel!

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel