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Date: Mon, 7 Oct 2024 12:27:19 -0700
From: Stephen Hemminger <stephen@networkplumber.org>
To: Thomas Monjalon <thomas@monjalon.net>
Cc: dev@dpdk.org, David Marchand <david.marchand@redhat.com>,
stable@dpdk.org, Morten =?UTF-8?B?QnLDuHJ1cA==?=
<mb@smartsharesystems.com>, Anatoly Burakov <anatoly.burakov@intel.com>,
Tyler Retzlaff <roretzla@linux.microsoft.com>, Narcisa Vasile
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Konstantin Ananyev <konstantin.v.ananyev@yandex.ru>, Andrew Rybchenko
<andrew.rybchenko@oktetlabs.ru>
Subject: Re: [PATCH v6 1/1] eal/unix: allow creating thread with real-time
priority
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In-Reply-To: <20231027081158.1358064-1-thomas@monjalon.net>
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Errors-To: dev-bounces@dpdk.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.
>=20
> There is a known issue with ring behaviour,
> but it should not be completely forbidden.
>=20
> 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.
>=20
> 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
>=20
> Signed-off-by: Thomas Monjalon <thomas@monjalon.net>
> Acked-by: Morten Br=C3=B8rup <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.