Convert the busy pwm from using a single calibration pass with a fixed
target into a self-correcting pwm that tries to adjust how long to sleep
on each pwm in order to converge at the target busy %%.
Being self-correcting, it should fare better against the more variable
systems CI presents.
v2: Be fair and equally strict for low/high busy %%
v3: target_idle_us and calculate expected from timing of each individual pass
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=105157
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
---
tests/perf_pmu.c | 74 ++++++++++++++++++++++++++------------------------------
1 file changed, 34 insertions(+), 40 deletions(-)
diff --git a/tests/perf_pmu.c b/tests/perf_pmu.c
index 7fab73e2..98d8dbff 100644
--- a/tests/perf_pmu.c
+++ b/tests/perf_pmu.c
@@ -1422,9 +1422,10 @@ accuracy(int gem_fd, const struct intel_execution_engine2 *e,
busy_us / 100) / target_busy_pct;
unsigned long pwm_calibration_us;
unsigned long test_us;
- double busy_r;
+ double busy_r, expected;
uint64_t val[2];
uint64_t ts[2];
+ int link[2];
int fd;
/* Sampling platforms cannot reach the high accuracy criteria. */
@@ -1450,14 +1451,16 @@ accuracy(int gem_fd, const struct intel_execution_engine2 *e,
assert_within_epsilon((double)busy_us / (busy_us + idle_us),
(double)target_busy_pct / 100.0, tolerance);
+ igt_assert(pipe(link) == 0);
+
/* Emit PWM pattern on the engine from a child. */
igt_fork(child, 1) {
struct sched_param rt = { .sched_priority = 99 };
- const unsigned long timeout[] = { pwm_calibration_us * 1000,
- test_us * 2 * 1000 };
- unsigned long sleep_busy = busy_us;
- unsigned long sleep_idle = idle_us;
+ const unsigned long timeout[] = {
+ pwm_calibration_us * 1000, test_us * 2 * 1000
+ };
struct drm_i915_gem_exec_object2 obj = {};
+ uint64_t total_busy_ns = 0, total_idle_ns = 0;
igt_spin_t *spin;
int ret;
@@ -1478,76 +1481,67 @@ 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 long busy_ns = 0, idle_ns = 0;
+ uint64_t busy_ns = -total_busy_ns;
+ uint64_t idle_ns = -total_idle_ns;
struct timespec test_start = { };
- unsigned long loops = 0;
- double err_busy, err_idle;
igt_nsec_elapsed(&test_start);
do {
struct timespec t_busy = { };
+ unsigned int target_idle_us;
igt_nsec_elapsed(&t_busy);
/* Restart the spinbatch. */
__rearm_spin_batch(spin);
__submit_spin_batch(gem_fd, &obj, e);
- measured_usleep(sleep_busy);
+ measured_usleep(busy_us);
igt_spin_batch_end(spin);
gem_sync(gem_fd, obj.handle);
- busy_ns += igt_nsec_elapsed(&t_busy);
+ total_busy_ns += igt_nsec_elapsed(&t_busy);
- idle_ns += measured_usleep(sleep_idle);
-
- loops++;
+ target_idle_us =
+ (100 * total_busy_ns / target_busy_pct - (total_busy_ns + total_idle_ns)) / 1000;
+ total_idle_ns += measured_usleep(target_idle_us);
} while (igt_nsec_elapsed(&test_start) < timeout[pass]);
- busy_ns = div_round_up(busy_ns, loops);
- idle_ns = div_round_up(idle_ns, loops);
-
- err_busy = __error(busy_ns / 1000, busy_us);
- err_idle = __error(idle_ns / 1000, idle_us);
-
- igt_info("%u: busy %lu/%lu %.2f%%, idle %lu/%lu %.2f%%\n",
- pass,
- busy_ns / 1000, busy_us, err_busy,
- idle_ns / 1000, idle_us, err_idle);
-
- if (pass == 0) {
- sleep_busy = (double)busy_us -
- (double)busy_us * err_busy / 100.0;
- sleep_idle = (double)idle_us -
- (double)idle_us * err_idle / 100.0;
- igt_info("calibrated sleeps ratio %.2f%% (%lu/%lu)\n",
- (double)sleep_busy /
- (sleep_busy + sleep_idle) * 100.0,
- sleep_busy, sleep_idle);
- }
+ busy_ns += total_busy_ns;
+ idle_ns += total_idle_ns;
+
+ expected = (double)busy_ns / (busy_ns + idle_ns);
+ igt_info("%u: busy %luus, idle %luus: %.2f%% (target: %lu%%)\n",
+ pass, busy_ns / 1000, idle_ns / 1000,
+ 100 * expected, target_busy_pct);
+ write(link[1], &expected, sizeof(expected));
}
igt_spin_batch_free(gem_fd, spin);
}
/* Let the child run. */
- usleep(pwm_calibration_us * 2);
+ read(link[0], &expected, sizeof(expected));
+ assert_within_epsilon(expected, target_busy_pct/100., 0.05);
/* Collect engine busyness for an interesting part of child runtime. */
fd = open_pmu(I915_PMU_ENGINE_BUSY(e->class, e->instance));
val[0] = __pmu_read_single(fd, &ts[0]);
- usleep(test_us / 2);
+ read(link[0], &expected, sizeof(expected));
val[1] = __pmu_read_single(fd, &ts[1]);
close(fd);
+ close(link[1]);
+ close(link[0]);
+
igt_waitchildren();
busy_r = (double)(val[1] - val[0]) / (ts[1] - ts[0]);
- igt_info("error=%.2f%% (%.2f%% vs %lu%%)\n",
- __error(busy_r, target_busy_pct / 100.0),
- busy_r * 100.0, target_busy_pct);
+ igt_info("error=%.2f%% (%.2f%% vs %.2f%%)\n",
+ __error(busy_r, expected), 100 * busy_r, 100 * expected);
- assert_within_epsilon(busy_r, (double)target_busy_pct / 100.0, 0.15);
+ assert_within_epsilon(busy_r, expected, 0.15);
+ assert_within_epsilon(1 - busy_r, 1 - expected, 0.15);
}
igt_main
