Re: [PATCH v1] perf test: Add a runs-per-test flag

[Ian Rogers]

On Mon, Nov 11, 2024 at 7:52 AM Liang, Kan <kan.liang@xxxxxxxxxxxxxxx> wrote:
>
>
>
> On 2024-11-09 11:02 a.m., Ian Rogers wrote:
> > To detect flakes it is useful to run tests more than once. Add a
> > runs-per-test flag that will run each test multiple times.
> >
> > Signed-off-by: Ian Rogers <irogers@xxxxxxxxxx>
> > ---
> >  tools/perf/tests/builtin-test.c | 38 ++++++++++++++++++++-------------
> >  1 file changed, 23 insertions(+), 15 deletions(-)
> >
> > diff --git a/tools/perf/tests/builtin-test.c b/tools/perf/tests/builtin-test.c
> > index d2cabaa8ad92..574fbd5caff0 100644
> > --- a/tools/perf/tests/builtin-test.c
> > +++ b/tools/perf/tests/builtin-test.c
> > @@ -42,6 +42,8 @@
> >  static bool dont_fork;
> >  /* Fork the tests in parallel and wait for their completion. */
> >  static bool sequential;
> > +/* Numer of times each test is run. */
> > +static unsigned int runs_per_test = 1;
> >  const char *dso_to_test;
> >  const char *test_objdump_path = "objdump";
> >
> > @@ -490,10 +492,10 @@ static int __cmd_test(struct test_suite **suites, int argc, const char *argv[],
> >                               len = strlen(test_description(*t, subi));
> >                               if (width < len)
> >                                       width = len;
> > -                             num_tests++;
> > +                             num_tests += runs_per_test;
> >                       }
> >               } else {
> > -                     num_tests++;
> > +                     num_tests += runs_per_test;
> >               }
> >       }
>
> Seems we just need to calculate the num_tests once at the end for each
> loop. Something as below may works. (not tested)
>
> @@ -482,20 +490,19 @@ static int __cmd_test(struct test_suite **suites,
> int argc, const char *argv[],
>
>         for (struct test_suite **t = suites; *t; t++) {
>                 int len = strlen(test_description(*t, -1));
> +               int subi = 0, subn = 1;
>
>                 if (width < len)
>                         width = len;
>
>                 if (has_subtests(*t)) {
> -                       for (int subi = 0, subn = num_subtests(*t); subi
> < subn; subi++) {
> +                       for (subn = num_subtests(*t); subi < subn; subi++) {
>                                 len = strlen(test_description(*t, subi));
>                                 if (width < len)
>                                         width = len;
> -                               num_tests++;
>                         }
> -               } else {
> -                       num_tests++;
>                 }
> +               num_tests += subn * runs_per_test;
>         }
>         child_tests = calloc(num_tests, sizeof(*child_tests));
>         if (!child_tests)

It's basically the same thing, instead of doing increments and then
multiplying by runs_per_test you just add on runs_per_test and avoid
the multiply.

> >       child_tests = calloc(num_tests, sizeof(*child_tests));
> > @@ -556,21 +558,25 @@ static int __cmd_test(struct test_suite **suites, int argc, const char *argv[],
> >                       }
> >
> >                       if (!has_subtests(*t)) {
> > -                             err = start_test(*t, curr, -1, &child_tests[child_test_num++],
> > -                                              width, pass);
> > -                             if (err)
> > -                                     goto err_out;
> > +                             for (unsigned int run = 0; run < runs_per_test; run++) {
> > +                                     err = start_test(*t, curr, -1, &child_tests[child_test_num++],
> > +                                                     width, pass);
> > +                                     if (err)
> > +                                             goto err_out;
> > +                             }
> >                               continue;
> >                       }
> > -                     for (int subi = 0, subn = num_subtests(*t); subi < subn; subi++) {
> > -                             if (!perf_test__matches(test_description(*t, subi),
> > -                                                     curr, argc, argv))
> > -                                     continue;
> > -
> > -                             err = start_test(*t, curr, subi, &child_tests[child_test_num++],
> > -                                              width, pass);
> > -                             if (err)
> > -                                     goto err_out;
> > +                     for (unsigned int run = 0; run < runs_per_test; run++) {
> > +                             for (int subi = 0, subn = num_subtests(*t); subi < subn; subi++) {
> > +                                     if (!perf_test__matches(test_description(*t, subi),
> > +                                                                     curr, argc, argv))
> > +                                             continue;
> > +
> > +                                     err = start_test(*t, curr, subi, &child_tests[child_test_num++],
> > +                                                     width, pass);
> > +                                     if (err)
> > +                                             goto err_out;
> > +                             }
>
> Can we add a wrapper for the start_test()? Something similar to below?
> It avoids adding the loop for every places using the start_test.
>
> +static int start_test(struct test_suite *test, int i, int subi, struct
> child_test **child,
> +               int width, int pass)
> +{
> +       for (unsigned int run = 0; run < runs_per_test; run++) {
> +               __start_test();
> +       }
> +}

I think the issue is the code has become overly indented. Having a
start_test function that starts some number of tests feels less than
intention revealing. Perhaps (in the future I'd like to tackle other
things for now, such as new TMAs :-) ) we can create all the child
tests in one pass, then just have start_test and finish_test work with
the child tests. (Off topic) Something else I'd like is to move the
slower running tests to the end of the list of tests so you can see
the earlier results while waiting.

Thanks,
Ian


> >                       }
> >               }
> >               if (!sequential) {
> > @@ -714,6 +720,8 @@ int cmd_test(int argc, const char **argv)
> >                   "Do not fork for testcase"),
> >       OPT_BOOLEAN('S', "sequential", &sequential,
> >                   "Run the tests one after another rather than in parallel"),
> > +     OPT_UINTEGER('r', "runs-per-test", &runs_per_test,
> > +                  "Run each test the given number of times, default 1"),
> >       OPT_STRING('w', "workload", &workload, "work", "workload to run for testing, use '--list-workloads' to list the available ones."),
> >       OPT_BOOLEAN(0, "list-workloads", &list_workloads, "List the available builtin workloads to use with -w/--workload"),
> >       OPT_STRING(0, "dso", &dso_to_test, "dso", "dso to test"),
>