[LTP] [PATCH v4 1/2] lib: introduce tst_timeout_remaining()

[Cyril Hrubis <chrubis@suse.cz>]

Hi!
> > > Fair enough, also the alarm() in the test library pid is set before we
> > > run the test setup, so if the test setup would take a few seconds we
> > > will be off with the calculation. Although that could be fixed by
> > > calling heartbeat before we run the loop in testrun(), which I guess
> > > should be done anyway. That in turn would allow for your patch to have
> > > the clock_gettime only in the heartbeat function, right?
> 
> Correct. We could replace it with call to hearbeat():
> 
> --- a/lib/tst_test.c
> +++ b/lib/tst_test.c
> @@ -929,9 +929,7 @@ static void testrun(void)
>         unsigned long long stop_time = 0;
>         int cont = 1;
>  
> -       if (tst_clock_gettime(CLOCK_MONOTONIC, &tst_start_time))
> -               tst_res(TWARN | TERRNO, "tst_clock_gettime() failed");
> -
> +       heartbeat();
>         add_paths();
>         do_test_setup();
>  
> but then we should get rid of extra alarm() call in tst_set_timeout(),
> because new hearbeat() call will do it anyway (it will send signal,
> and handler in lib will call alarm()):
> 
> @@ -1038,9 +1036,7 @@ void tst_set_timeout(int timeout)
>                 results->timeout/3600, (results->timeout%3600)/60,
>                 results->timeout % 60);
>  
> -       if (getpid() == lib_pid)
> -               alarm(results->timeout);
> -       else
> +       if (getpid() != lib_pid)
>                 heartbeat();
>  }

That would mean that the test library will not timeout unless the child
process managed to send it a signal, so I would like to keep it there,
since it's more robust that way.

Well, we may change this, so that the first alarm in the test library
runs with something as 30 seconds, which should be enough before we get
the heartbeat() from the child that would reset the alarm with a correct
timemout.

> > 
> > Actually we would have to do the heartbeat before and after the setup.
> 
> Why after setup? Doesn't the time spent in setup count towards test time?

Actually it does, the setup + first iteration of the test share the
timeout, since the first call to alarm(timeout) in the test library
happens before we call the test setup. Subsequent iterations does not
run the setup at all, so the whole timeout applies only to the actuall
test function.

This haven't been a problem since our tests are usually very fast, but
it would probably be better if we do heartbeat() before and after
do_test_setup().

-- 
Cyril Hrubis
chrubis@suse.cz