From: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
A subtest to verify that the engine busyness is reported with expected
accuracy on platforms where the feature is available.
We test three patterns: 2%, 50% and 98% load per engine.
v2:
* Use spin batch instead of nop calibration.
* Various tweaks.
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
---
tests/perf_pmu.c | 141 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 141 insertions(+)
diff --git a/tests/perf_pmu.c b/tests/perf_pmu.c
index 935fee03b253..3ca88bcc6976 100644
--- a/tests/perf_pmu.c
+++ b/tests/perf_pmu.c
@@ -35,6 +35,7 @@
#include <dirent.h>
#include <time.h>
#include <poll.h>
+#include <sched.h>
#include "igt.h"
#include "igt_core.h"
@@ -983,6 +984,136 @@ test_rc6(int gem_fd)
assert_within_epsilon(busy - prev, 0.0, tolerance);
}
+static uint64_t __pmu_read_single(int fd, uint64_t *ts)
+{
+ uint64_t data[2];
+
+ igt_assert_eq(read(fd, data, sizeof(data)), sizeof(data));
+
+ *ts = data[1];
+
+ return data[0];
+}
+
+static double __error(double val, double ref)
+{
+ return (100.0 * val / ref) - 100.0;
+}
+
+static void debug_error(const char *str, double val, double ref)
+{
+ igt_debug("%s=%.2f%% (%.2f/%.2f)\n", str, __error(val, ref), val, ref);
+}
+
+static void log_error(const char *str, double val, double ref)
+{
+ debug_error(str, val, ref);
+ igt_info("%s=%.2f%%\n", str, __error(val, ref));
+}
+
+static void
+accuracy(int gem_fd, const struct intel_execution_engine2 *e,
+ unsigned long target_busy_pct)
+{
+ const unsigned int test_us = 1e6;
+ unsigned long busy_us = 2500;
+ unsigned long idle_us = 100 * (busy_us - target_busy_pct *
+ busy_us / 100) / target_busy_pct;
+ double busy_r;
+ uint64_t val[2];
+ uint64_t ts[2];
+ int fd;
+
+ /* Sampling platforms cannot reach the high accuracy criteria. */
+ igt_require(intel_gen(intel_get_drm_devid(gem_fd)) >= 8);
+
+ while (idle_us < 2500) {
+ busy_us *= 2;
+ idle_us *= 2;
+ }
+
+ assert_within_epsilon((double)busy_us / (busy_us + idle_us),
+ (double)target_busy_pct / 100.0, tolerance);
+
+ /* Emit PWM pattern on the engine from a child. */
+ igt_fork(child, 1) {
+ struct sched_param rt = { .sched_priority = 99 };
+ unsigned long overhead_ns = 0;
+ unsigned long loops;
+ unsigned long i;
+
+ /* We need the best sleep accuracy we can get. */
+ igt_require(sched_setscheduler(0,
+ SCHED_FIFO | SCHED_RESET_ON_FORK,
+ &rt) == 0);
+
+ /* Measure setup overhead. */
+ loops = test_us / 8000;
+ for (i = 0; i < loops; i++) {
+ struct timespec start = { };
+ igt_spin_t *spin;
+ unsigned int ns;
+
+ igt_nsec_elapsed(&start);
+ spin = igt_spin_batch_new(gem_fd, 0, e2ring(gem_fd, e),
+ 0);
+ igt_spin_batch_end(spin);
+ ns = igt_nsec_elapsed(&start);
+ gem_sync(gem_fd, spin->handle);
+ igt_spin_batch_free(gem_fd, spin);
+ overhead_ns += ns;
+ usleep(1000);
+ }
+
+ overhead_ns /= test_us / loops;
+ igt_debug("spin setup overhead = %luus\n", overhead_ns / 1000);
+ igt_assert(overhead_ns < busy_us * 1000);
+
+ /* Emit PWM busy signal. */
+ loops = test_us / (busy_us + idle_us);
+ for (i = 0; i < loops; i++) {
+ struct timespec start = { };
+ igt_spin_t *spin;
+ unsigned int ns;
+
+ spin = igt_spin_batch_new(gem_fd, 0, e2ring(gem_fd, e),
+ 0);
+ ns = measured_usleep(busy_us - overhead_ns / 1000);
+ igt_spin_batch_end(spin);
+ gem_sync(gem_fd, spin->handle);
+ igt_nsec_elapsed(&start);
+ igt_spin_batch_free(gem_fd, spin);
+ debug_error("busy error", ns, busy_us * 1000);
+ ns = igt_nsec_elapsed(&start);
+
+ if (ns > idle_us * 1000)
+ ns = 0;
+ else
+ ns = idle_us;
+ ns = measured_usleep(ns);
+ debug_error("idle error", ns, idle_us * 1000);
+ }
+ }
+
+ /* Let the child run. */
+ usleep(test_us / 4);
+
+ /* Collect engine busyness for a subset 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);
+ val[1] = __pmu_read_single(fd, &ts[1]);
+ close(fd);
+
+ igt_waitchildren();
+
+ busy_r = (double)(val[1] - val[0]) / (ts[1] - ts[0]);
+
+ log_error("error", busy_r, target_busy_pct / 100.0);
+
+ assert_within_epsilon(busy_r, (double)target_busy_pct / 100.0, 0.15);
+}
+
igt_main
{
const unsigned int num_other_metrics =
@@ -1011,6 +1142,8 @@ igt_main
invalid_init();
for_each_engine_class_instance(fd, e) {
+ const unsigned int pct[] = { 2, 50, 98 };
+
/**
* Test that a single engine metric can be initialized.
*/
@@ -1077,6 +1210,14 @@ igt_main
*/
igt_subtest_f("multi-client-%s", e->name)
multi_client(fd, e);
+
+ /**
+ * Check engine busyness accuracy is as expected.
+ */
+ for (i = 0; i < ARRAY_SIZE(pct); i++) {
+ igt_subtest_f("busy-accuracy-%u-%s", pct[i], e->name)
+ accuracy(fd, e, pct[i]);
+ }
}
/**
--
2.14.1
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