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    SubjectRe: rt20 scheduling latency testcase and failure data
    Date
    On Saturday 13 May 2006 11:21, Lee Revell wrote:
    > On Sat, 2006-05-13 at 11:06 -0700, Darren Hart wrote:
    > > 1 [softirq-timer/0]
    >
    > What happens if you set the softirq-timer threads to 99?
    >

    After setting all 4 softirq-timer threads to prio 99 I seemed to get only 2
    failures in 100 runs. #51 slept too long (10ms too long!), the latency
    appeared after the sleep in #90 (nearly 483ms worth). Those latencies seem
    huge to me.

    ITERATIONS 0-50 Passed

    ITERATION 51
    -------------------------------
    Scheduling Latency
    -------------------------------

    Running 10000 iterations with a period of 5 ms
    Expected running time: 50 s

    ITERATION DELAY(US) MAX_DELAY(US) FAILURES
    --------- --------- ------------- --------
    7000 10197 10197 1

    PERIOD MISSED!
    scheduled delta: 4079 us
    actual delta: 14263 us
    latency: 10183 us
    ---------------------------------------
    previous start: 35010197 us
    now: 35011117 us
    scheduled start: 35005000 us
    next scheduled start is in the past!


    Start Latency: 114 us: FAIL
    Min Latency: 9 us: PASS
    Avg Latency: 7 us: PASS
    Max Latency: 10197 us: FAIL
    Failed Iterations: 1

    ITERATIONS 52-89 Passed

    ITERATION 90
    -------------------------------
    Scheduling Latency
    -------------------------------

    Running 10000 iterations with a period of 5 ms
    Expected running time: 50 s

    ITERATION DELAY(US) MAX_DELAY(US) FAILURES
    --------- --------- ------------- --------
    2747 9 20 0

    PERIOD MISSED!
    scheduled delta: 4072 us
    actual delta: 4079 us
    latency: 6 us
    ---------------------------------------
    previous start: 13735009 us
    now: 14218183 us
    scheduled start: 13740000 us
    next scheduled start is in the past!


    Start Latency: 112 us: FAIL
    Min Latency: 8 us: PASS
    Avg Latency: 2 us: PASS
    Max Latency: 20 us: PASS
    Failed Iterations: 0

    ITERATIONS 91-99 Passed

    Thanks,

    --
    Darren Hart
    IBM Linux Technology Center
    Realtime Linux Team
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