[LTP] tst_fuzzy_sync01 sporadically fails

[Richard Palethorpe <rpalethorpe@suse.de>]

Hello Petr,

Petr Vorel <pvorel@suse.cz> writes:

> Hi Richie,
>
>> Hello Petr,
>
>> Petr Vorel <pvorel@suse.cz> writes:
>
>> > Hi Richie,
>
>> > ...
>> >> > tst_fuzzy_sync01.c:224: TFAIL: acs:1  act:1  art:3  | =:3    -:2999996 +:1   
>
>> >> It looks like the CI machines are too noisy/contended. The avg_dev is
>> >> very high. Probably we could relax the dev_ratio threshold to 0.2 or
>> >> 0.3. Although we would still get failures occassionally. As this is a
>> >> probabalistic test.
>> > Test is failing on my laptop, thus haven't enabled it in CI.
>> > But maybe it'll be working on it more reliably than my busy machine.
>
>> Is it really that busy? Perhaps we should increase the dev ratio
>> threshold. Clearly the deviations from contention are not enough to
>> reproduce the races, but are enough to prevent the radomization phase.
> I probably did some VM testing or kernel compilation or something.
> I'll try to enable for next patchset version it to see how it works on CI.
>
>> > But I'd prefer to wasting time with false positives, thus I guess we should
>> > enable only tests which are working reliably.
>
>> >> Could you change the script so that it passes so long as the test
>> >> returns TPASS or TFAIL?
>> > Well, accepting TFAIL sounds a bit strange to me :).
>> > Also next effort will be (at least for shell tests) to compare actual test
>> > output. Obviously that will not be straightforward for some tests, which aren't
>> > reproducible (avg = 11729ns could be matched by regex, but having more variants
>> > of results is kind of special case).
>
>> >> We don't want TBROK, TCONF or no result.
>> > FYI in my CI patchset is TCONF accepted. Motivation was to not require root for
>> > make test as some tests needed it. Thus TCONF will be a special case, then I
>> > guess we could add tst_fuzzy_sync01 accepting TFAIL as a special case.
>
>> At least if we run the tests and look for TPASS or TFAIL, we will catch
>> segfaults and similar.
>
>> Also, for fuzzy sync, returning TCONF would be a major error. It should
>> run on all systems.
> Well, TCONF should be used on places where it's really a configuration issue.
> IMHO only TBROK and TFAIL should be a problem. Or is fuzzy sync part somehow
> special in this?

I can't imagine any Linux config where fuzzy sync won't work. Even if we
are compiling with some libc that doesn't have POSIX threads, we can
work around that. Probably if it returns TCONF it's because some other
library func has an error in it.

For example if tst_ncpus_available starts aborting with TCONF. Then that
is an error. Fuzzy Sync should be able to work around that.

-- 
Thank you,
Richard.