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SubjectRe: scheduler ignores need_resched flag in 2.2.x and 2.3.x?
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Victor writes:
>I agree that you found a bug, I disagree that you will ever get 100% timing
>correctness from Linux except at the cost of making the kernel unmaintainable.
>
>Furthermore, if you do similar timing tests on VxWorks, Win-CE, and etc, I bet
>you will find that 100 milliseconds is not impossible.
>Note that even QNX quotes "typical" interrupt latency times.

True, except that we're not discussing interrupt latency time
here. We're discussing the time between a task being marked as
runnable, and the time that it actually starts running (with the
presumption that its marked SCHED_FIFO, and is thus entitled to run
immediately). Obviously, poor interrupt latencies will lead to bad
scheduling jitter. But we actually have pretty reasonable and
consistent interrupt latencies, plus some bugs that lead to bad
scheduling jitter.

--p

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