Re: [PATCH 2/6] posix-cpu-timers: Don't start process wide cputime counter if timer is disabled

[Peter Zijlstra]

On Wed, Jun 16, 2021 at 01:26:30PM +0200, Peter Zijlstra wrote:
> Right, so by the time patch #5 comes around, you seem to be at the point
> where you can do:
> 
>  * fetch cputime and start threadgroup counter
> 
>  * possibly arm timer

- possibly

> 
>  * if expired:
>    - fire now
>    - if armed, disarm (which leads to stop)
> 
> Which is the other 'obvious' solution to not starting it.

So we unconditionally start and arm, and then have the early expire do
the same things as regular expire.