Our observation is that the systematic error is proportional to the
number of iterations we perform; the suspicion is that it directly
correlates with the number of sleeps. Reduce the number of iterations,
to try and keep the error in check.
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
---
tests/perf_pmu.c | 34 +++++++++++++++++++++-------------
1 file changed, 21 insertions(+), 13 deletions(-)
diff --git a/tests/perf_pmu.c b/tests/perf_pmu.c
index 9a20abb6b..5a26d5272 100644
--- a/tests/perf_pmu.c
+++ b/tests/perf_pmu.c
@@ -1521,14 +1521,13 @@ static void __rearm_spin_batch(igt_spin_t *spin)
static void
accuracy(int gem_fd, const struct intel_execution_engine2 *e,
- unsigned long target_busy_pct)
+ unsigned long target_busy_pct,
+ unsigned long target_iters)
{
- unsigned long busy_us = 10000 - 100 * (1 + abs(50 - target_busy_pct));
- unsigned long idle_us = 100 * (busy_us - target_busy_pct *
- busy_us / 100) / target_busy_pct;
const unsigned long min_test_us = 1e6;
- const unsigned long pwm_calibration_us = min_test_us;
- const unsigned long test_us = min_test_us;
+ unsigned long pwm_calibration_us;
+ unsigned long test_us;
+ unsigned long cycle_us, busy_us, idle_us;
double busy_r, expected;
uint64_t val[2];
uint64_t ts[2];
@@ -1538,18 +1537,27 @@ accuracy(int gem_fd, const struct intel_execution_engine2 *e,
/* Sampling platforms cannot reach the high accuracy criteria. */
igt_require(gem_has_execlists(gem_fd));
- while (idle_us < 2500) {
+ /* Aim for approximately 100 iterations for calibration */
+ cycle_us = min_test_us / target_iters;
+ busy_us = cycle_us * target_busy_pct / 100;
+ idle_us = cycle_us - busy_us;
+
+ while (idle_us < 2500 || busy_us < 2500) {
busy_us *= 2;
idle_us *= 2;
}
+ cycle_us = busy_us + idle_us;
+ pwm_calibration_us = target_iters * cycle_us / 2;
+ test_us = target_iters * cycle_us;
- igt_info("calibration=%lums, test=%lums; ratio=%.2f%% (%luus/%luus)\n",
- pwm_calibration_us / 1000, test_us / 1000,
- (double)busy_us / (busy_us + idle_us) * 100.0,
+ igt_info("calibration=%lums, test=%lums, cycle=%lums; ratio=%.2f%% (%luus/%luus)\n",
+ pwm_calibration_us / 1000, test_us / 1000, cycle_us / 1000,
+ (double)busy_us / cycle_us * 100.0,
busy_us, idle_us);
- assert_within_epsilon((double)busy_us / (busy_us + idle_us),
- (double)target_busy_pct / 100.0, tolerance);
+ assert_within_epsilon((double)busy_us / cycle_us,
+ (double)target_busy_pct / 100.0,
+ tolerance);
igt_assert(pipe(link) == 0);
@@ -1796,7 +1804,7 @@ igt_main
for (i = 0; i < ARRAY_SIZE(pct); i++) {
igt_subtest_f("busy-accuracy-%u-%s",
pct[i], e->name)
- accuracy(fd, e, pct[i]);
+ accuracy(fd, e, pct[i], 10);
}
igt_subtest_f("busy-hang-%s", e->name)
--
2.18.0
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