[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Xen-devel] [PATCH 6 of 8 [RFC]] libxc: introduce xc_domain_move_memory

On 02/05/13 15:32, Tim Deegan wrote:

This looks like a promising start.  Two thoughts:

1. You currently move memory into a bufferm free it, allocate new memory
    and restore the contents.  Copying directly from old to new would be
    significantly faster, and you could do it for _most_ batches:
    - copy old batch 0 to the backup buffer; free old batch 0;
    - allocate new batch 1; copy batch 1 directly; free old batch 1;
    - allocate new batch n; copy batch n directly; free old batch n;
    - allocate new batch 0; copy batch 0 from the backup buffer.

Hmm -- isn't it the case that if there is not *free* memory lying around somewhere, then this operation is fairly pointless? What will happen is that after freeing batch 0, "allocate new batch 1" will get that memory. So copying it to a temporary buffer in dom0 seems like not a particularly useful thing to do -- it should try to allocate a new buffer to copy into directly, and if that fails, just say "No point trying -- no empty memory to move into."

Unless of course we were trying to do this to two (or more) VMs at the same time, but that seems like the next level.


Xen-devel mailing list



Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.