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

Thomas Gleixner
2021-04-10T09:04:57Z

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?

Thanks,

tglx