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    SubjectRe: [PATCH v9 0/5] make balloon pages movable by compaction
    On 08/26/2012 03:58 AM, Michael S. Tsirkin wrote:
    > On Sat, Aug 25, 2012 at 02:24:55AM -0300, Rafael Aquini wrote:
    >> Memory fragmentation introduced by ballooning might reduce significantly
    >> the number of 2MB contiguous memory blocks that can be used within a guest,
    >> thus imposing performance penalties associated with the reduced number of
    >> transparent huge pages that could be used by the guest workload.
    >> This patch-set follows the main idea discussed at 2012 LSFMMS session:
    >> "Ballooning for transparent huge pages" --
    >> to introduce the required changes to the virtio_balloon driver, as well as
    >> the changes to the core compaction & migration bits, in order to make those
    >> subsystems aware of ballooned pages and allow memory balloon pages become
    >> movable within a guest, thus avoiding the aforementioned fragmentation issue
    > Meta-question: are there any numbers showing gain from this patchset?
    > The reason I ask, on migration we notify host about each page
    > individually. If this is rare maybe the patchset does not help much.
    > If this is common we would be better off building up a list of multiple
    > pages and passing them in one go.

    The gain is in getting a better THP allocation rate inside the
    guest, allowing applications to run faster.

    The rarer it is for this code to run, the better - it means we
    are getting the benefits without the overhead :)

    All rights reversed

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      Last update: 2012-08-26 17:21    [W:0.025 / U:6.652 seconds]
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