[Intel-gfx] [PATCH i-g-t v3] tests/kms_flip: Adjust tolerance when counting frames

[Chris Wilson]

On Fri, May 13, 2016 at 02:45:09PM +0300, Gabriel Feceoru wrote:
> basic-flip-vs-wf_vblank subtest sometimes fails asserting counted frames to
> be aproximately equal with the estimated number.
> 
> This is a false negative, one of the reasons being the precision lost when
> truncating a fractional number.
> 
> Fixed this by using floating point arithmetic.
> 
> Cc: Jani Nikula <jani.nikula at intel.com>
> Cc: Daniel Vetter <daniel.vetter at intel.com>
> Signed-off-by: Gabriel Feceoru <gabriel.feceoru at intel.com>
> ---
>  tests/kms_flip.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/tests/kms_flip.c b/tests/kms_flip.c
> index eda2fcc..6ec97d0 100644
> --- a/tests/kms_flip.c
> +++ b/tests/kms_flip.c
> @@ -1182,13 +1182,13 @@ 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;
> +		double expected;
>  		int count = es->count;
>  
>  		count *= o->seq_step;
> -		expected = elapsed / frame_time(o);

int expected = count * frame_time(o);
igt_assert_f(100 * expected >= elasped * 99 && 100 * count <= expected * 101,
	     "dropped frames, expected %d, counted %d, encoder type %d\n",
	     elapsed / frame_time(o), count, o->kencoder[0]->encoder_type);

if I understood your concern correctly, as the only loss of precison
there would be from calculating 'expected'.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre