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    SubjectRe: The performance and behaviour of the anti-fragmentation related patches
    > But if you don't require a lot of higher order allocations anyway, then
    > guest fragmentation caused by ballooning doesn't seem like much problem.

    If you only need to allocate 1 page size and smaller allocations then no it's not a
    problem. As soon as you go above that it will be. You don't need to go all the way
    up to MAX_ORDER size to see an impact, it's just increasingly more severe as you get
    away from 1 page and towards MAX_ORDER.

    > If you need higher order allocations, then ballooning is bad because of
    > fragmentation, so you need memory unplug, so you need higher order
    > allocations. Goto 1.

    Yes, it's a closed loop. But hotplug isn't the only one that needs higher order
    allocations. In fact it's pretty far down the list. I look at it like this, a lot
    of users need high order allocations for better performance and things like on-demand
    hugepages. As a bonus you get memory hot-remove.

    > Balooning probably does skew memory management stats and watermarks, but
    > that's just because it is implemented as a module. A couple of hooks
    > should be enough to allow things to be adjusted?

    That is a good idea independent of the current discussion.

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      Last update: 2007-03-05 16:23    [W:0.028 / U:125.768 seconds]
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