Sleeping in poll or on a futex already supports nanosecond resolution if the platform supports it. We use it when a scheduler decides that it needs to sleep a fraction of a millisecond before the timer would fire. i.e. timer should fire at 5ms, but scheduler decides to sleep at 2.545 ms.
What would need to be done is to change the resolution of the timer wheel that dispatches timeouts, and of course expose the APIs.
Regarding which API would be the best to use, I’ve not really experimented all that much. clock_gettime in virtualized environments does have problems, but when running native it usually works good enough.
I think that in general though if you need nanosecond accuracy of your timers, linux may not be the operating system to use.
). My guess is that the timer wheel would introduce quite some load on the CPU compared to 1ms slots but I might be wrong.