Thursday, December 13, 2018

Re: Setitimer() resolution?

On Thu, Dec 13, 2018 at 09:27:12PM +0000, Paul Swanson wrote:
> Hi,
>
> I'm trying to understand how interval timers work in OpenBSD,
> but I'm a little stuck on this line from the getitimer / setitimer man page:
>
> "Time values smaller than the resolution of the system clock
> are rounded up to this resolution (typically 10 milliseconds)."
>
> Does this mean that 10 milliseconds is the shortest interval possible
> with a system interval timer?
>
> If so, are there other userland options for more precise timers?
>
> I'm mainly interested in AMD64.
>
> Thanks in advance,
>
> Paul

The resolution of the system clock is governed by hz.

man 9 hz

On amd64, it's set to 100, which means 10ms. We don't have a tickless model
to support arbitrary precision timers.

-ml

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