Re: [PATCH] x86: use cpufreq_quick_get() for /proc/cpuinfo "cpu MHz" again

[Linus Torvalds]

On Thu, Nov 9, 2017 at 2:30 PM, Rafael J. Wysocki <rafael@xxxxxxxxxx> wrote:
>
> c_start() can run aperfmperf_snapshot_khz() on all CPUs upfront (say
> in parallel), then wait for a while (say 5 ms; the current 20 ms wait
> is overkill) and then aperfmperf_snapshot_khz() can be run once on
> each CPU in show_cpuinfo() without taking the "stale cache" threshold
> into account.

Yeah, that won't work.

What could work is to do that "smp_call_function_many()" at open time,
and *not* set the "wait" flag, but do it entirely asynchronously.

But I don't think that's an option for 4.14 ;(

So I guess I'll have to revert.

            Linus