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    SubjectRe: 2.6.9-rc1: page_referenced_one() CPU consumption
    Nikita Danilov wrote:

    > I ran tests few times, and difference between patched and un-patched
    > kernels is within noise, so you are right, try-lock does not help.
    >

    Well I'm glad - because I much prefer the spin_lock over the trylock :)

    > But now I have new great idea instead. :)
    >
    > I think page_referenced() should transfer dirtiness to the struct page
    > as it scans pte's. Basically the earlier we mark page dirty the better
    > file system write-back performs, because page has more chances to be
    > bulk-written by ->writepages(). This is better than my previous patches
    > to this end (that used separate function to transfer dirtiness from
    > pte's to the page), because
    >
    > - locking overhead is avoided
    >
    > - it's simpler.
    >
    > Nick, are you still in business of benchmarking random VM patches? :-)
    >

    Yeah I am, and I do have that patch sitting around. It can *really*
    help for writeout via maped memory (obviously doesn't help write()).

    I think Andrew's response was that it can theoretically cause writeout
    for workloads that don't want it, so I should come up with at least
    one real-world improvement!
    -
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