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    SubjectRe: Scheduler ( was: Just a second ) ...

    On Tue, 18 Dec 2001, Alan Cox wrote:
    > > at 2*2 bytes per sample and 44kHz would mean that a 1kB DMA buffer empties
    > > in less than 1/100th of a second, but at least it should be < 200 irqs/sec
    > > rather than >400).
    > With a few exceptions the applications tend to use 4K or larger DMA chunks
    > anyway. Very few need tiny chunks.

    Doing another grep seems to imply that none of the other drivers even
    allow as small chunks as the sb driver does, 32 byte "events" is just
    ridiculous. At simple 2-channel, 16-bits, CD-quality sound, that's a DMA
    event every 0.18 msec (5500 times a second, 181 _micro_seconds appart).

    I obviously agree that the app shouldn't even ask for small chunks:
    whether a mp3 player reacts within 1/10th or 1/1000th of a second of the
    user asking it to switch tracks, nobody can even tell. So an mp3 player
    should probably use a big fragment size on the order of 4kB or similar
    (that still gives max fragment latency of 0.022 seconds, faster than
    humans can react).

    So it sounds like a player sillyness, but I don't think the driver should
    even allow such waste of resources, considering that no other driver
    allows it either..


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