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    SubjectRe: [QUICKLIST 0/6] Arch independent quicklists V1
    On Sun, 11 Mar 2007, David Miller wrote:

    > I'm going to make the radical declaration that it be perhaps often
    > better to always initialize page table chunks to all zeros on
    > allocation.

    That is the case if most of the page is going to be used soon. If we have
    sparse access patterns then not zeroing can avoid uselessly bringing
    cachelines in.

    > The reason is that every time I've monitored the allocation patterns
    > of these things on SMP, the page table chunks always get released on a
    > different cpu than where they were initialized.

    But its even advantageous in that case for sparse allocs.

    > The allocator side just does nothing but emit L2 cache line ownership
    > transactions as the pte page is touched. Especially on chips like
    > PowerPC where zero initialization is absurdly cheap, we can avoid all
    > of the cache line transfers if we just initialize it at allocation
    > time.

    We have no need to touch all the cache lines w/o initialization if we
    alloc from the quicklist. And that is a performance benefit.

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