On 13.05.2016 15:00, Chris Wilson wrote:
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@xxxxxxxxx> Cc: Daniel Vetter <daniel.vetter@xxxxxxxxx> Signed-off-by: Gabriel Feceoru <gabriel.feceoru@xxxxxxxxx> --- 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'.
That would also do it, but with care where to use the cast: int expected = (int)((double)count * frame_time(o)); vs int expected = count * (int)frame_time(o); Gabriel.
-Chris
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