[LTP] [PATCH] fzsync: don't compare spins_avg (float) against 1 (int)

[Jan Stancek]

tst_fzsync_pair.spins is increased at least by one on every iteration.
If during all calibration loops, both A and B manage to complete at
nearly same time, then spins is increased only by one.

spins_avg starts as 0, and tst_exp_moving_avg() will move it closer
and closer to 1, but it will never be 1:
        float f = 0; int i;
        for (i = 0; i < 4096; i++)
                f = tst_exp_moving_avg(0.25f, 1, f);
        printf("%.15f %d\n", f, f >= 1);
	$ 0.999999880790710 0

which on rare occasion can cause: "Can't calculate random delay".

Compare against float slightly smaller than 1.
Also print stats one more time when we hit the warning.

Signed-off-by: Jan Stancek <jstancek@redhat.com>
---
 include/tst_fuzzy_sync.h | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/include/tst_fuzzy_sync.h b/include/tst_fuzzy_sync.h
index de0402c9bbe9..2c0389c5d63e 100644
--- a/include/tst_fuzzy_sync.h
+++ b/include/tst_fuzzy_sync.h
@@ -73,6 +73,8 @@
 /* how much of exec time is sampling allowed to take */
 #define SAMPLING_SLICE 0.5f
 
+#define EPSILON 0.999f
+
 /** Some statistics for a variable */
 struct tst_fzsync_stat {
 	float avg;
@@ -477,7 +479,7 @@ static void tst_fzsync_pair_update(struct tst_fzsync_pair *pair)
 			tst_res(TINFO, "Minimum sampling period ended");
 			tst_fzsync_pair_info(pair);
 		}
-	} else if (fabsf(pair->diff_ab.avg) >= 1 && pair->spins_avg.avg >= 1) {
+	} else if (fabsf(pair->diff_ab.avg) > EPSILON && pair->spins_avg.avg > EPSILON) {
 		per_spin_time = fabsf(pair->diff_ab.avg) / pair->spins_avg.avg;
 		time_delay = drand48() * (pair->diff_sa.avg + pair->diff_sb.avg)
 			- pair->diff_sb.avg;
@@ -495,6 +497,7 @@ static void tst_fzsync_pair_update(struct tst_fzsync_pair *pair)
 		}
 	} else if (!pair->sampling) {
 		tst_res(TWARN, "Can't calculate random delay");
+		tst_fzsync_pair_info(pair);
 		pair->sampling = -1;
 	}
 
-- 
1.8.3.1