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    SubjectRe: [Question] Explanation of zero-copy networking
    Alan Cox wrote:
    > > so there's still single copy for write() of a mmap()ed page?
    >
    > An mmap page will go direct to disk.

    Looking at the 2.4.4 code, mmap() of file followed by write() to socket
    will copy the data once.

    I could be mistaken (only glanced at the code quickly) but I base that
    on the only call to ->sendpage being through sendfile.

    So yes, there's a single copy overhead for mmap()+write().

    -- Jamie
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