Re: [patch V6 01/37] tracing/hwlat: Use ktime_get_mono_fast_ns()

From: Thomas Gleixner
Date: Wed May 20 2020 - 18:21:17 EST


Peter Zijlstra <peterz@xxxxxxxxxxxxx> writes:

> On Sat, May 16, 2020 at 01:45:48AM +0200, Thomas Gleixner wrote:
>> Timestamping in the hardware latency detector uses sched_clock() underneath
>> and depends on CONFIG_GENERIC_SCHED_CLOCK=n because sched clocks from that
>> subsystem are not NMI safe.
>
> AFAICT that's not actually true, see commit:
>
> 1809bfa44e10 ("timers, sched/clock: Avoid deadlock during read from NMI")
>
> that said, no objection to switching to ktime, people that run HPET
> clocks deserve all the pain and suffering available with those setups.

Correct ...