Re: [PATCH v4] posix-timers: Prefer delivery of signals to the current thread

Oleg Nesterov
2023-01-28T20:16:25Z

Forgot to mention ...

On 01/28, Oleg Nesterov wrote:
>
> Dmitry,
>
> I agree with what you said, just one note...
>
> On 01/27, Dmitry Vyukov wrote:
> >
> > After this change the test passes quickly (within a second for me).
>
> yet perhaps it makes sense to slightly change it? It does
>
> +static void *distribution_thr(void *arg) {
> + while (__atomic_load_n(&remain, __ATOMIC_RELAXED));
> + return NULL;
> +}
>
> so distribution_thr() eats CPU even after this thread gets a signal and thus
> (in theory) it can "steal" cpu_timer_fire() from other threads unpredictably
> long ? How about
>
> - while (__atomic_load_n(&remain, __ATOMIC_RELAXED));
> + while (__atomic_load_n(&got_signal, __ATOMIC_RELAXED));
>
> ?

Of course, in this case it also makes sense to change the main() function the
same way and add BUG_ON(remain) after the "for (...) pthread_join()" block.

Oleg.