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Re: nanosleep() for shorted than schedule slice

On 07/03/17 07:25, Michael van Elst wrote: (Johnny Billquist) writes:

Having the normal wall clock driven by a tick interrupt has its points.
We usually avoid this and use what hardware timer the platform offers.

Basically yes, but as these timers wrap after a while we need to checkpoint (call tc_windup() often enough) the hw counters at at least twice the wrapping frequency.. It is not magic either, but needs some care handling
to keep our monotonic- and wall-clock- time keeping and NTP happy.

If I remember correctly FreeBSD already made the step to tickless, last time I looked.
It's just that for high resolution timers, ticks are not a good source.
For anything else, they are just fine. So why conflate the two?
Because you don't need two clock interrupts. The regular interrupt is
just another event that happens to be scheduled in a regular interval.


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