On 16/02/2021 12:49, Chris Wilson wrote:
Quoting Tvrtko Ursulin (2021-02-16 10:50:50)
From: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
Test that periodic reads of engine busyness against a constant 100% load
are within the 5000ppm tolerance when comparing perf timestamp versus
counter values.
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
---
tests/i915/perf_pmu.c | 46 ++++++++++++++++++++++++++++++++++++++-----
1 file changed, 41 insertions(+), 5 deletions(-)
diff --git a/tests/i915/perf_pmu.c b/tests/i915/perf_pmu.c
index 50b5c82bc472..728312be5293 100644
--- a/tests/i915/perf_pmu.c
+++ b/tests/i915/perf_pmu.c
@@ -26,6 +26,7 @@
#include <stdio.h>
#include <string.h>
#include <fcntl.h>
+#include <float.h>
#include <inttypes.h>
#include <errno.h>
#include <signal.h>
@@ -46,6 +47,7 @@
#include "igt_perf.h"
#include "igt_sysfs.h"
#include "igt_pm.h"
+#include "igt_stats.h"
#include "sw_sync.h"
IGT_TEST_DESCRIPTION("Test the i915 pmu perf interface");
@@ -278,8 +280,11 @@ static void end_spin(int fd, igt_spin_t *spin, unsigned int flags)
static void
single(int gem_fd, const struct intel_execution_engine2 *e, unsigned int flags)
{
+ unsigned int loops = flags & FLAG_LONG ? 20 : 1;
+ double err_min = DBL_MAX, err_max = -DBL_MAX;
unsigned long slept;
igt_spin_t *spin;
+ igt_stats_t s;
uint64_t val;
int fd;
@@ -290,11 +295,40 @@ single(int gem_fd, const struct intel_execution_engine2 *e, unsigned int flags)
else
spin = NULL;
- val = pmu_read_single(fd);
- slept = measured_usleep(batch_duration_ns / 1000);
- if (flags & TEST_TRAILING_IDLE)
- end_spin(gem_fd, spin, flags);
- val = pmu_read_single(fd) - val;
+ igt_stats_init_with_size(&s, loops);
+
+ while (--loops) {
while (loops--)
/o\
Yeah.. At least I know the oddity is related to sampling. Since even on
Haswell:
(perf_pmu:1591) DEBUG: time=500207720 busy=500037022 error=-341.25ppm
(perf_pmu:1591) DEBUG: time=500252520 busy=500033517 error=-437.78ppm
(perf_pmu:1591) DEBUG: time=500187490 busy=499999817 error=-375.21ppm
(perf_pmu:1591) DEBUG: time=500244871 busy=499999837 error=-489.83ppm
(perf_pmu:1591) DEBUG: time=500268670 busy=499999477 error=-538.10ppm
(perf_pmu:1591) DEBUG: time=500245246 busy=500000432 error=-489.39ppm
(perf_pmu:1591) DEBUG: time=500245735 busy=499999306 error=-492.62ppm
(perf_pmu:1591) DEBUG: time=500270045 busy=500001747 error=-536.31ppm
(perf_pmu:1591) DEBUG: time=500254286 busy=499998162 error=-511.99ppm
(perf_pmu:1591) DEBUG: time=500247790 busy=500000347 error=-494.64ppm
(perf_pmu:1591) DEBUG: time=500250261 busy=500000257 error=-499.76ppm
(perf_pmu:1591) DEBUG: time=500250005 busy=500008177 error=-483.41ppm
(perf_pmu:1591) DEBUG: time=500249065 busy=499991867 error=-514.14ppm
(perf_pmu:1591) DEBUG: time=500249725 busy=500000371 error=-498.46ppm
(perf_pmu:1591) DEBUG: time=500250335 busy=499999772 error=-500.88ppm
(perf_pmu:1591) DEBUG: time=500258691 busy=499999937 error=-517.24ppm
(perf_pmu:1591) DEBUG: time=500239980 busy=500001037 error=-477.66ppm
(perf_pmu:1591) DEBUG: time=500240791 busy=504999361 error=9512.56ppm
And this last one is way more than one sampling period. I'll be thinking
about this in the background.
Regards,
Tvrtko
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