Re: [LTP] [REGRESSION] pidns05 timeout (was: [PATCH 1/2] lib: multiply the timeout if detect slow kconfigs)

[Petr Vorel <pvorel@suse.cz>]

> > On Thu, Jan 16, 2025 at 6:42 AM Petr Vorel <pvorel@suse.cz> wrote:

> > > Hi Li, Cyril, all,

> > > ...
> > > > +++ b/lib/tst_test.c
> > > > @@ -555,9 +555,6 @@ static int multiply_runtime(int max_runtime)

> > > >       parse_mul(&runtime_mul, "LTP_RUNTIME_MUL", 0.0099, 100);

> > > > -     if (tst_has_slow_kconfig())
> > > > -             max_runtime *= 4;
> > > > -
> > > >       return max_runtime * runtime_mul;
> > > >  }

> > > > @@ -1706,6 +1703,9 @@ unsigned int tst_multiply_timeout(unsigned int
> > > timeout)
> > > >       if (timeout < 1)
> > > >               tst_brk(TBROK, "timeout must to be >= 1! (%d)", timeout);

> > > > +     if (tst_has_slow_kconfig())
> > > > +             timeout *= 4;

> > > FYI this change, merged as 893ca0abe7 ("lib: multiply the timeout if
> > > detect slow
> > > kconfigs") caused a regression on *all* tests which use tst_net.sh.
> ...

> FYI also at least pidns05.c sometimes fails due timeout with this change.
> On some of SLES product previously pidns05.c run for 3 sec. With this change it
> runs 12s and therefore timeouts.

I'm sorry for a wrong report. Looking about it twice there is "*** stack
smashing detected ***: terminated" => some other problem, which causes slow
down. IMHO it's not optimal to run the detection many times + basically now
requiring kernel config for each LTP test, but performance impact is probably
low.

Kind regards,
Petr

> In pidns05.c case child is run 5x. For each of this child we again detect if we
> run on slow config. Maybe we should have used struct tst_test member to cache
> the value.

> What bothers me more that how much time we waste for whole LTP testing with
> repeatedly detecting slow config for all tests (runtest/syscalls has 1457 items,
> we run it more times for each product with different kernel cmdline parameters).
> I don't know what was supposed to be fixed by this feature, is it really worth
> of slowdown? Why not just set LTP_RUNTIME_MUL=2 on slow kernels? We could have
> tool which would 'exit 1' on "slow" kernel and 'exit 0' on normal kernel to do
> automatic detection, which could be run by frameworks just once.

> Kind regards,
> Petr

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