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    SubjectRe: a joint letter on low latency and Linux

    > > On Wed, 5 Jul 2000, Richard Gooch wrote:
    > > > RTLinux doesn't have to be conservative this way. It doesn't have to
    > > > work around broken hardware ("Oh, it hangs? Go use decent hardware").
    > > > This is a key point I'm finding difficult to get across.
    > >
    > > Youre saying we cant do better than 4000ms? Ouch.
    > I'm saying we can't do better than N ms, where N is an unknown
    > quantity (because all drivers and core kernel code has not been
    > audited, and said auditing would take man-years and be an ongoing
    > project). And people have reported large values of N. Apparently the
    > PS/2 driver has N >= 50. There may be other stuff that is much worse.
    > I think Andrew Morton measured something with N = 160.

    With fbcon on machine with loaded PCI bus (usb modem), N can be ~500,
    even more with really full screen. You know, fbcon is running with
    interrupts disabled.

    > But people should not fool themselves into thinking that anybody has a
    > clue how big N could be. Even with a specific hardware combination,
    > there may always be some kernel slow algorithm that is lurking, ready
    > to blow out N.

    I'm "In my country we have almost anarchy and I don't care."
    Panos Katsaloulis describing me w.r.t. patents at

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