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    SubjectRe: [RFC] mmaped copy too slow?
    Hi Rik

    > While being able to deal with used-once mappings in page reclaim
    > could be a good idea, this would require us to be able to determine
    > the difference between a page that was accessed once since it was
    > faulted in and a page that got accessed several times.

    it makes sense that read ahead hit assume used-once mapping, may be.
    I will try it.

    (may be, i can repost soon)

    > Given that page faults have overhead too, it does not surprise me
    > that read+write is faster than mmap+memcpy.
    > In threaded applications, page fault overhead will be worse still,
    > since the TLBs need to be synchronized between CPUs (at least at
    > reclaim time).

    but current is unnecessary large performance difference.
    I hope improvement it because copy by mmapd is very common operation.

    > Maybe we should just advise people to use read+write, since it is
    > faster than mmap+memcpy?

    Time is solved to it :)

    - kosaki

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      Last update: 2008-01-15 04:23    [W:0.023 / U:34.472 seconds]
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