[PATCH] eal/unix: allow creating thread with real-time priority

[Morten Brørup]

> From: Thomas Monjalon [mailto:thomas at monjalon.net]
> Sent: Tuesday, 24 October 2023 14.54
> 
> When adding an API for creating threads,
> the real-time priority has been forbidden on Unix.
> 
> There is a known issue with ring behaviour,
> but it should not be completely forbidden.
> 
> Fixes: ca04c78b6262 ("eal: get/set thread priority per thread identifier")
> Fixes: ce6e911d20f6 ("eal: add thread lifetime API")
> Fixes: a7ba40b2b1bf ("drivers: convert to internal control threads")
> Cc: stable at dpdk.org
> 
> Signed-off-by: Thomas Monjalon <thomas at monjalon.net>
> ---

[...]

> @@ -815,7 +815,9 @@ Known Issues
> 
>    4. It MAY be used by preemptible multi-producer and/or preemptible multi-
> consumer pthreads whose scheduling policy are all SCHED_OTHER(cfs), SCHED_IDLE
> or SCHED_BATCH. User SHOULD be aware of the performance penalty before using
> it.
> 
> -  5. It MUST not be used by multi-producer/consumer pthreads, whose
> scheduling policies are SCHED_FIFO or SCHED_RR.
> +  5. It MUST not be used by multi-producer/consumer pthreads
> +     whose scheduling policies are ``SCHED_FIFO``
> +     or ``SCHED_RR`` (``RTE_THREAD_PRIORITY_REALTIME_CRITICAL``).

Do the RTS or HTS ring modes make any difference here?

Anyway, I agree that real-time priority should not be forbidden on Unix.

Acked-by: Morten Brørup <mb at smartsharesystems.com>