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



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

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

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