Re: [PATCH v7 clocksource 5/5] clocksource: Do pairwise clock-desynchronization checking

Paul E. McKenney
2021-04-11T00:21:55Z

On Sat, Apr 10, 2021 at 11:04:54AM +0200, Thomas Gleixner wrote:
> On Fri, Apr 02 2021 at 15:49, paulmck wrote:
> > From: "Paul E. McKenney" <paulmck@kernel.org>
> >
> > Although smp_call_function() has the advantage of simplicity, using
> > it to check for cross-CPU clock desynchronization means that any CPU
> > being slow reduces the sensitivity of the checking across all CPUs.
> > And it is not uncommon for smp_call_function() latencies to be in the
> > hundreds of microseconds.
> >
> > This commit therefore switches to smp_call_function_single(), so that
> > delays from a given CPU affect only those measurements involving that
> > particular CPU.
>
> Is there any reason I'm missing why this is not done right in patch 3/5
> which introduces this synchronization check?

None at all. I will merge this into 3/5.

Thanx, Paul