Re: nanosleep() for shorted than schedule slice

[Frank Kardel <kardel%kardel.name@localhost>]

On 07/03/17 07:25, Michael van Elst wrote:
> bqt%softjar.se@localhost (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.
Frank