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    SubjectRe: Is sendfile all that sexy?
    Hi,

    On Thu, 18 Jan 2001, Linus Torvalds wrote:

    > > Actually, this is a great example, because at one point I was working
    > > on a device interface which would offload all of the disk-disk copying
    > > overhead to the disks themselves, and not involve the CPU/RAM at all.
    >
    > It's a horrible example.
    >
    > device-to-device copies sound like the ultimate thing.
    >
    > They suck. They add a lot of complexity and do not work in general. And,
    > if your "normal" usage pattern really is to just move the data without
    > even looking at it, then you have to ask yourself whether you're doing
    > something worthwhile in the first place.
    >
    > Not going to happen.

    device-to-device is not the same as disk-to-disk. A better example would
    be a streaming file server. Slowly the pci bus becomes a bottleneck, why
    would you want to move the data twice over the pci bus if once is enough
    and the data very likely not needed afterwards? Sure you can use a more
    expensive 64bit/60MHz bus, but why should you if the 32bit/30MHz bus is
    theoretically fast enough for your application?
    So I'm not advising it as "the ultimate thing", but I don't understand,
    why it shouldn't happen.

    bye, Roman

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