[LTP] Realtime testsuite

[Petr Vorel]

Hi all,

we have ticket about realtime testsuite evaluation [1].
I put there some old investigation made by Mel Gorman.
At the time we wanted to migrate everything to rt-tests.

Cyril considered sched_football useful enough also for regular non-RT systems,
thus I ported it to new library in 43dc52fafa ("sched_football: Rewrite into new
API"). And there is a followup patchset [3] [4] which among other things always
enables realtime and put sched_football also to runtest/sched.

But we should decide what to do with the rest. Would you have time to have look
if something else is good enough to be kept in LTP?

I suggest to contribute pi_perf and prio-wake to rt-tests and ask also
linux-rt-users community to have look on the tests (specially
realtime/stress/pi-tests and testcases/realtime/perf/latency which Mel did not
reviewed) and act based on their investigation (port or remove).

BTW Mel reported about sched_football:

	Interesting, might be worth reimplementing. The
	concept is interesting as a test but it has
	weaknesses. The sched_yield usage is one thing
	but also, it only works if the number of players
	equals the number of CPUs and small changes in
	sched_yield semantics would break the test.

IMHO we should remove -n option, so that ncpu is always used. I also wonder,
what breaks -i2.

Kind regards,
Petr

[1] https://github.com/linux-test-project/ltp/issues/1078
[2] https://git.kernel.org/pub/scm/utils/rt-tests/rt-tests.git
[3] https://patchwork.ozlabs.org/project/ltp/list/?series=415662&state=*
[4] https://lore.kernel.org/ltp/20240717171713.687339-1-pvorel@suse.cz/