[Intel-gfx] [PATCH i-g-t] tests/kms_flip: Adjust tolerance when counting frames

[Chris Wilson]

On Tue, May 17, 2016 at 09:30:59AM +0200, Daniel Vetter wrote:
> On Tue, May 10, 2016 at 05:15:37PM +0300, Gabriel Feceoru wrote:
> > 
> > 
> > On 10.05.2016 16:52, Jani Nikula wrote:
> > >On Tue, 10 May 2016, Gabriel Feceoru <gabriel.feceoru at intel.com> wrote:
> > >>Comparing 2 numbers with 1% accuracy depends on which one is the
> > >>reference. If count == 100 and expected == 99 this condition fails,
> > >>although it should pass.
> > >
> > >Well, the expectation should be the reference. If you expect 50 at 50%
> > >tolerance, 25..75 is okay. 100 is clearly out of tolerance, but your
> > >method would accept it too.
> > >
> > >Would it help to round the lower limit down and upper limit up? I think
> > >that would be more acceptable.
> > 
> > Yes, you are right. I'll adjust it to 98/100 and 102/100.
> 
> Maybe also extract the computation for lower/upper limit into local
> variables, to make the code less dense and easier to understand.

Just because I have this lying around (untested):

diff --git a/tests/kms_flip.c b/tests/kms_flip.c
index eda2fcc..22b9c9d 100644
--- a/tests/kms_flip.c
+++ b/tests/kms_flip.c
@@ -1182,14 +1182,14 @@ static void check_final_state(struct test_output *o, struct event_state *es,
        /* Verify we drop no frames, but only if it's not a TV encoder, since
         * those use some funny fake timings behind userspace's back. */
        if (o->flags & TEST_CHECK_TS && !analog_tv_connector(o)) {
-               int expected;
-               int count = es->count;
+               int count = es->count * o->seq_step;
+               unsigned int min = frame_time(o) * (count - 1);
+               unsigned int max = frame_time(o) * (count + 1);
 
-               count *= o->seq_step;
-               expected = elapsed / frame_time(o);
-               igt_assert_f(count >= expected * 99/100 && count <= expected * 101/100,
+               igt_assert_f(elapsed > min && elapsed < max,
                             "dropped frames, expected %d, counted %d, encoder type %d\n",
-                            expected, count, o->kencoder[0]->encoder_type);
+                            elapsed / frame_time(o), count,
+                            o->kencoder[0]->encoder_type);
        }
 }

-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre