Victor Yodaiken wrote:
> Docs are going to be written soon, I swear.
> The idea is simple. If you set a timer to interrupt every 1000 time
> units then if you have a single task with period 1000 things work out great.
> If you add a task with period 500, then you can simply get the clock to
> interrupt every 500 ticks.
> Now add a task with period 1291. One option is to make the clock
> interrupt very 200 ticks and then sit on the timer 91 ticks until
> it's time to run the third task. But if you add a task with period 558
> even this solution is not good. So, RTL has a "oneshot" option, where
> the timer period is dynamically reset by the schduler ever interrupt.
> For example, we set the clock to interupt after 558 ticks.
> reset it to interrupt after another 442 ticks to get to 1000
> reset it to interrupt after another 291 ticks
> the disadvantage of one-shot on uniprocessor x86 machines is that
> reprogramming the clock takes 10 microseconds or so. If you can use
> the periodic mode, it's more efficient in reprogramming time. but
> if your schedule does not fit a good period, then oneshot is
> much better.
>
> In situations where we can use on board timers, e.g. the APIC timer, the
> oneshot reprogram is fast enough to make it a better tradeoff.
>
Hi there,
isn't this oneshot technic used in the KURT UTIME Patch, too?
Greeting
S.Heursch
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