Re: [PATCH v6 1/1] eal/unix: allow creating thread with real-time priority

[Stephen Hemminger <stephen@networkplumber.org>]

On Fri, 27 Oct 2023 10:08:52 +0200
Thomas Monjalon <thomas@monjalon.net> wrote:

> 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.
> 
> Real-time thread can block some kernel threads on the same core,
> making the system unstable.
> That's why a sleep is added in the test thread,
> and a warning is logged when using real-time priority.
> 
> 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@dpdk.org
> 
> Signed-off-by: Thomas Monjalon <thomas@monjalon.net>
> Acked-by: Morten Brørup <mb@smartsharesystems.com>
> ---

If RT threads are allowed on Linux, then a couple more things are necessary.

1. A functional test, maybe something with two threads exchanging packets
   ping-pong or something similar and show that the test does not crash
   or hang the CI system.

2. Sufficient documentation in programmers guide. Probably need a whole
   chapter on what is RT, when to use RT, and caveats.
   Make it clear to users that RT is not a faster mode, it is more about
   working with existing RT applications.