Re: [PATCH v0.9.1 3/6] sched/umcg: implement UMCG syscalls

On Mon, Nov 29, 2021 at 11:07:07PM +0100, Thomas Gleixner wrote:

On Fri, Nov 26 2021 at 22:52, Peter Zijlstra wrote:

The size is the same, i.e. 1 bit per nanosecond :)

:-)

quoted

The only time that's relevant though is when you're going to mix these
timestamps with CLOCK_THREAD_CPUTIME_ID, which might just be
interesting.

Uuurg. If you want to go towards CLOCK_THREAD_CPUTIME_ID, that's going
to be really nasty. Actually you can sleep on that clock, but that's a
completely different universe. If anything like that is desired then we
need to rewrite that posix CPU timer muck completely with all the bells
and whistels and race conditions attached to it. *Shudder*

Oh, I wasn't thinking anything as terrible as that. Sleeping on that
clock is fundamentally daft since it doesn't run when thats is
sleeping, consider trying to sleep on your own runtime :-)

I was only considering combining THREAD_CPUTIME timestamps with the
UMCG timestamps to compute how much unmanaged time there was, or other
such things.

Anyway, lets forget I bought this up and assume that for practical
purposes all [ns] are of equal length.