Re: [PATCH PREEMPT_RT] kcov: fix locking splat from kcov_remote_start()

Thomas Gleixner
2021-08-11T12:27:16Z

On Wed, Aug 11 2021 at 11:00, Sebastian Andrzej Siewior wrote:
> On 2021-08-10 22:38:30 [+0200], Thomas Gleixner wrote:
>> And that matters because? kcov has a massive overhead and with that
>> enabled you care as much about latencies as you do when running with
>> lockdep enabled.
>
> I wasn't aware of that. However, with that local_irq_save() ->
> local_lock_irqsave() swap and that first C code from
> Documentation/dev-tools/kcov.rst I don't see any spike in cyclictest's
> results. Maybe I'm not using it right…

The problem starts with remote coverage AFAICT.