[lkml]   [2000]   [Jul]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    SubjectAn important fact about real time computing
    The first sentence my professor maid on the real time computing
    course was :

    "A common misconception : Real-time computing is fast computing."

    I missed the real-time and low latency debate, but reading the
    kernel traffic pages [*] I saw that this misconception is very

    For example Linus himself said :

    > I personally would rather see that nobody ever needed RTlinux
    > at all. I think hard realtime is a waste of time, myself, and
    > only to be used for the case where the CPU speed is not
    > overwhelmingly fast enough (and these days, for most problems
    > the CPU _is_ so overwhelmingly "fast enough" that hard realtime
    > should be a non-issue).

    And on other place :

    > If you're doing just audio that needs approximately 1%
    > of the CPU resources, and you have to use hard-realtime,
    > the system needs work.

    And also:

    > I think RTLinux is perfect for those things that truly need
    > latency guarantees: no OS at _all_ in the way. But using it
    > for "normal" stuff like just streaming audio and video is
    > overkill. They don't have microsecond latency requirements.

    Processor speed (and the size/length of the deadline) is
    irrelevant. Even with a 10 GHz Pentium-X
    your audio will pop if the IDE driver disables interrupts
    long enough. Or if you are sorting a long list with an O(n^2)
    algorithm ( I don't know an actual example from kernel, but
    maybe some memory management code might do this ).

    ( and video _does_ have latency requirements, not microsecond
    but around 20 millisecond )

    Again , real time is making the dead-line, not
    making the deadline fast.

    David Balazic

    * -

    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to
    Please read the FAQ at

     \ /
      Last update: 2005-03-22 13:57    [W:0.027 / U:5.936 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site