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    SubjectRe: [Fwd: Re: [patch] Real-Time Preemption, -RT-2.6.9-mm1-V0.4]
    On Sun, 31 Oct 2004 13:48:28 +0100
    Ingo Molnar <mingo@elte.hu> wrote:

    >
    > * Ingo Molnar <mingo@elte.hu> wrote:
    >
    > > ok, could you try the -RT-V0.6.0 patch i've just uploaded? It could i
    > > believe improve these latencies.
    >
    > hm, CONFIG_PARPORT_1284 seems broken, and USB too, it locks up during
    > bootup. Investigating ...

    i will try anyways since i don't use neither USB nor my parallel port :)

    also, i have uploaded an overhauled version of the wakeup timer program. It
    now deferres all output to another SCHED_FIFO thread [with prio 1 lower than
    the main process]. The data is passed via a lockless fifo [ripped from jack
    sourcecode]. Also it handles commandline options better and has sensible [?]
    defaults:

    ~/source/my_projects/wakeup$ ./rtc_wakeup -h
    usage: wakeup [options]
    options:
    -f freqency(hz) (default 1024)
    -p realtime prio (default 90(91))
    -n max number of interrupts (default 0: run until stopped)
    -t jitter threshold (%) (default 5)
    -o history_file (default /dev/null)
    -h show help

    The "history" file contains three rows: irq #, cycle count at wakeup,
    jitter(%). The first few entries are probably off [due to startup stuff, all
    reporting during runtime takes only irq's after the third into account, to
    avoid the startup mess]..

    grab it at http://affenbande.org/~tapas/rtc_wakeup.tgz

    Here's a typical run (still on V0.5.16, will try V0.6 now):

    ~/source/my_projects/rtc_wakeup$ ./rtc_wakeup
    rtc_wakeup - press ctrl-c to stop
    freq: 1024
    max # of irqs: 0 (run until stopped)
    jitter threshold: 5%
    output filename: /dev/null
    rt priority: 90(91)
    getting cpu speed
    1194909286.409 Hz (1194.909 MHz)
    # of cycles for "perfect" period: 1166903
    setting up ringbuffer
    setting up consumer thread
    setting up /dev/rtc.
    locking memory...
    turning irq on, beginning measurement (might take a while).
    new max. jitter: 0.268231%
    threshold violated: 2523891286957 (26.3406%)
    new max. jitter: 26.3406%
    threshold violated: 2523892156958 (25.4436%)
    threshold violated: 2523896074240 (36.5712%)
    new max. jitter: 36.5712%
    threshold violated: 2523896831195 (35.1313%)
    threshold violated: 2523899757527 (50.2766%)
    new max. jitter: 50.2766%
    threshold violated: 2523900328433 (51.0751%)
    new max. jitter: 51.0751%
    threshold violated: 2523903338753 (57.0041%)
    new max. jitter: 57.0041%
    threshold violated: 2523903827419 (58.1228%)
    new max. jitter: 58.1228%
    threshold violated: 2523905321471 (28.0357%)
    threshold violated: 2523906161154 (28.0417%)
    threshold violated: 2523909924647 (22.6959%)
    threshold violated: 2523911166386 (6.41322%)
    threshold violated: 2523911990002 (29.4186%)
    threshold violated: 2523913267054 (9.43943%)
    threshold violated: 2523914321799 (9.6116%)
    threshold violated: 2523915653813 (14.1495%)
    threshold violated: 2523916760657 (5.14687%)
    threshold violated: 2523917830826 (8.28981%)
    threshold violated: 2523920520433 (29.74%)
    threshold violated: 2523921329137 (30.6966%)
    done.
    total # of irqs: 2754
    missed irqs: 0
    threshold violations: 20
    max jitter: 58.1228%


    flo
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