Normalize the variance to stddev, and remove some redundant steps in
computing the time from itself.
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
---
tests/perf_pmu.c | 22 +++++++++++++---------
1 file changed, 13 insertions(+), 9 deletions(-)
diff --git a/tests/perf_pmu.c b/tests/perf_pmu.c
index 5a26d5272..4e8da3d94 100644
--- a/tests/perf_pmu.c
+++ b/tests/perf_pmu.c
@@ -1577,8 +1577,8 @@ accuracy(int gem_fd, const struct intel_execution_engine2 *e,
/* 1st pass is calibration, second pass is the test. */
for (int pass = 0; pass < ARRAY_SIZE(timeout); pass++) {
unsigned int target_idle_us = idle_us;
- uint64_t busy_ns = 0, idle_ns = 0;
struct timespec start = { };
+ uint64_t busy_ns = 0;
unsigned long pass_ns = 0;
double avg = 0.0, var = 0.0;
unsigned int n = 0;
@@ -1589,6 +1589,7 @@ accuracy(int gem_fd, const struct intel_execution_engine2 *e,
unsigned long loop_ns, loop_busy;
struct timespec _ts = { };
double err, tmp;
+ uint64_t now;
/* PWM idle sleep. */
_ts.tv_nsec = target_idle_us * 1000;
@@ -1605,14 +1606,13 @@ accuracy(int gem_fd, const struct intel_execution_engine2 *e,
igt_spin_batch_end(spin);
/* Time accounting. */
- loop_ns = igt_nsec_elapsed(&start);
- loop_busy = loop_ns - loop_busy;
- loop_ns -= pass_ns;
+ now = igt_nsec_elapsed(&start);
+ loop_busy = now - loop_busy;
+ loop_ns = now - pass_ns;
+ pass_ns = now;
busy_ns += loop_busy;
total_busy_ns += loop_busy;
- idle_ns += loop_ns - loop_busy;
- pass_ns += loop_ns;
total_ns += loop_ns;
/* Re-calibrate. */
@@ -1628,10 +1628,14 @@ accuracy(int gem_fd, const struct intel_execution_engine2 *e,
var += (err - avg) * (err - tmp);
} while (pass_ns < timeout[pass]);
+ pass_ns = igt_nsec_elapsed(&start);
expected = (double)busy_ns / pass_ns;
- igt_info("%u: busy %"PRIu64"us, idle %"PRIu64"us -> %.2f%% (target: %lu%%; average=%.2f, variance=%f)\n",
- pass, busy_ns / 1000, idle_ns / 1000,
- 100 * expected, target_busy_pct, avg, var / n);
+
+ igt_info("%u: busy %"PRIu64"us, idle %"PRIu64"us -> %.2f%% (target: %lu%%; average=%.2f±%.3f%%)\n",
+ pass, busy_ns / 1000, (pass_ns - busy_ns) / 1000,
+ 100 * expected, target_busy_pct,
+ avg, sqrt(var / n));
+
write(link[1], &expected, sizeof(expected));
}
--
2.18.0
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