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    SubjectRe: [PATCH v2 2/2] xen/setup: Remap Xen Identity Mapped RAM
    On 20/07/14 01:01, Matt Rushton wrote:
    > Instead of ballooning up and down dom0 memory this remaps the existing mfns
    > that were replaced by the identity map. The reason for this is that the
    > existing implementation ballooned memory up and and down which caused dom0
    > to have discontiguous pages. In some cases this resulted in the use of bounce
    > buffers which reduced network I/O performance significantly. This change will
    > honor the existing order of the pages with the exception of some boundary
    > conditions.
    >
    > To do this we need to update both the Linux p2m table and the Xen m2p table.
    > Particular care must be taken when updating the p2m table since it's important
    > to limit table memory consumption and reuse the existing leaf pages which get
    > freed when an entire leaf page is set to the identity map. To implement this,
    > mapping updates are grouped into blocks with table entries getting cached
    > temporarily and then released.
    >
    > On my test system before:
    > Total pages: 2105014
    > Total contiguous: 1640635
    >
    > After:
    > Total pages: 2105014
    > Total contiguous: 2098904

    Applied to devel/for-linus-3.17

    Thanks.

    David


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