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    SubjectRe: [RFC/T/D][PATCH 2/2] Linux/Guest cooperative unmapped page cache control
    On 06/14/2010 08:16 PM, Balbir Singh wrote:
    > * Dave Hansen<dave@linux.vnet.ibm.com> [2010-06-14 10:09:31]:
    >
    >
    >> On Mon, 2010-06-14 at 22:28 +0530, Balbir Singh wrote:
    >>
    >>> If you've got duplicate pages and you know
    >>> that they are duplicated and can be retrieved at a lower cost, why
    >>> wouldn't we go after them first?
    >>>
    >> I agree with this in theory. But, the guest lacks the information about
    >> what is truly duplicated and what the costs are for itself and/or the
    >> host to recreate it. "Unmapped page cache" may be the best proxy that
    >> we have at the moment for "easy to recreate", but I think it's still too
    >> poor a match to make these patches useful.
    >>
    >>
    > That is why the policy (in the next set) will come from the host. As
    > to whether the data is truly duplicated, my experiments show up to 60%
    > of the page cache is duplicated.

    Isn't that incredibly workload dependent?

    We can't expect the host admin to know whether duplication will occur or
    not.

    --
    error compiling committee.c: too many arguments to function



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