On Sat, Dec 10 2022 at 07:52, Biju Das wrote:
> scheduling tick is 4millisec. so if we want callback at 1 microsec,
> then we need to use clock_nanosleep. Getting 1 microsec callback to
> user space is challenging as the scheduling tick is only 4 millisec.
The tick is only relevant if high resolution timers are disabled because
then hrtimers are expired in the tick. If high resolution timers are
enabled then the hrtimer expiry happens at the exact expiry time.
What's challenging about the 1 microsecond accuracy is that the system
immanent latencies are already in that range. So while the timer fires
exactly, the actual execution of the woken up task in user space is not
exact as that is subject to the worst case sum of latencies in the
system.
Thanks,
tglx
