Re: [PATCH] sched/psi: clamp negative cpu_clock() skew

[Johannes Weiner]

On Tue, Sep 29, 2026 at 10:17:40AM +0200, Peter Zijlstra wrote:
> On Tue, Sep 29, 2026 at 10:10:04AM +0200, Peter Zijlstra wrote:
> 
> > > When running browser workloads on an Intel N100 with a sustained
> > > psi.mem.some of 2-3%, this underflow is observed once every couple of
> > > hours.
> 
> Reading is hard. This is sad, that's a relatively modern chip :-(

I'm still struggling, but I'm under the weather so bear with me.

That's a cpu_clock() implementation issue, right? "The value for
cpu_clock(i) is monotonic for constant i". Presumably violating that
would be a problem beyond psi?