[igt-dev] [PATCH i-g-t 3/6] tests/perf: new tests for parameterized OA buffer polling

Umesh Nerlige Ramappa
2020-03-03T22:38:15Z

From: Lionel Landwerlin <lionel.g.landwerlin@intel.com>

2 new tests verifying that the OA buffer is properly checked at the
frequency specified by userspace.

v2: (Umesh)
- Capture start_times in test_polling
- Second parameterized test used a 500us hrtimer. Occassionally, this
timing does not fall within the duration/100 requirement for the time
spent in kernel. Change this value to 2ms to accommodate all
platforms.

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Signed-off-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
---
tests/perf.c | 136 ++++++++++++++++++++++++++++++++++++++-------------
1 file changed, 102 insertions(+), 34 deletions(-)

diff --git a/tests/perf.c b/tests/perf.c
index 189c6aa1..37dc1db1 100644
--- a/tests/perf.c
+++ b/tests/perf.c
@@ -234,6 +234,24 @@ get_oa_format(enum drm_i915_oa_format format)
return gen8_oa_formats[format];
}

+static char *
+pretty_print_oa_period(uint64_t oa_period_ns)
+{
+ static char result[100];
+ static const char *units[4] = { "ns", "us", "ms", "s" };
+ double val = oa_period_ns;
+ int iter = 0;
+
+ while (iter < (ARRAY_SIZE(units) - 1) &&
+ val >= 1000.0f) {
+ val /= 1000.0f;
+ iter++;
+ }
+
+ snprintf(result, sizeof(result), "%.3f%s", val, units[iter]);
+ return result;
+}
+
static void
__perf_close(int fd)
{
@@ -1927,15 +1945,9 @@ get_time(void)
* kernelspace.
*/
static void
-test_blocking(void)
+test_blocking(uint64_t requested_oa_period, bool set_kernel_hrtimer, uint64_t kernel_hrtimer)
{
- /* ~40 milliseconds
- *
- * Having a period somewhat > sysconf(_SC_CLK_TCK) helps to stop
- * scheduling (liable to kick in when we make blocking poll()s/reads)
- * from interfering with the test.
- */
- int oa_exponent = max_oa_exponent_for_period_lte(40000000);
+ int oa_exponent = max_oa_exponent_for_period_lte(requested_oa_period);
uint64_t oa_period = oa_exponent_to_ns(oa_exponent);
uint64_t properties[] = {
/* Include OA reports in samples */
@@ -1945,11 +1957,16 @@ test_blocking(void)
DRM_I915_PERF_PROP_OA_METRICS_SET, test_set->perf_oa_metrics_set,
DRM_I915_PERF_PROP_OA_FORMAT, test_set->perf_oa_format,
DRM_I915_PERF_PROP_OA_EXPONENT, oa_exponent,
+
+ /* Kernel configuration (optional) */
+ DRM_I915_PERF_PROP_POLL_OA_DELAY, kernel_hrtimer,
};
struct drm_i915_perf_open_param param = {
.flags = I915_PERF_FLAG_FD_CLOEXEC |
I915_PERF_FLAG_DISABLED,
- .num_properties = sizeof(properties) / 16,
+ .num_properties = (set_kernel_hrtimer ?
+ (ARRAY_SIZE(properties) / 2) :
+ ((ARRAY_SIZE(properties) / 2) - 1)),
.properties_ptr = to_user_pointer(properties),
};
uint8_t buf[1024 * 1024];
@@ -1971,7 +1988,7 @@ test_blocking(void)
* the knowledge that that the driver uses a 200Hz hrtimer (5ms period)
* to check for data and giving some time to read().
*/
- int min_iterations = (test_duration_ns / (oa_period + 6000000ull));
+ int min_iterations = (test_duration_ns / (oa_period + kernel_hrtimer + kernel_hrtimer / 5));

int64_t start, end;
int n = 0;
@@ -1981,9 +1998,10 @@ test_blocking(void)
times(&start_times);

igt_debug("tick length = %dns, test duration = %"PRIu64"ns, min iter. = %d,"
- " estimated max iter. = %d, oa_period = %"PRIu64"ns\n",
+ " estimated max iter. = %d, oa_period = %s\n",
(int)tick_ns, test_duration_ns,
- min_iterations, max_iterations, oa_period);
+ min_iterations, max_iterations,
+ pretty_print_oa_period(oa_period));

/* In the loop we perform blocking polls while the HW is sampling at
* ~25Hz, with the expectation that we spend most of our time blocked
@@ -2085,15 +2103,9 @@ test_blocking(void)
}

static void
-test_polling(void)
+test_polling(uint64_t requested_oa_period, bool set_kernel_hrtimer, uint64_t kernel_hrtimer)
{
- /* ~40 milliseconds
- *
- * Having a period somewhat > sysconf(_SC_CLK_TCK) helps to stop
- * scheduling (liable to kick in when we make blocking poll()s/reads)
- * from interfering with the test.
- */
- int oa_exponent = max_oa_exponent_for_period_lte(40000000);
+ int oa_exponent = max_oa_exponent_for_period_lte(requested_oa_period);
uint64_t oa_period = oa_exponent_to_ns(oa_exponent);
uint64_t properties[] = {
/* Include OA reports in samples */
@@ -2103,12 +2115,17 @@ test_polling(void)
DRM_I915_PERF_PROP_OA_METRICS_SET, test_set->perf_oa_metrics_set,
DRM_I915_PERF_PROP_OA_FORMAT, test_set->perf_oa_format,
DRM_I915_PERF_PROP_OA_EXPONENT, oa_exponent,
+
+ /* Kernel configuration (optional) */
+ DRM_I915_PERF_PROP_POLL_OA_DELAY, kernel_hrtimer,
};
struct drm_i915_perf_open_param param = {
.flags = I915_PERF_FLAG_FD_CLOEXEC |
I915_PERF_FLAG_DISABLED |
I915_PERF_FLAG_FD_NONBLOCK,
- .num_properties = sizeof(properties) / 16,
+ .num_properties = (set_kernel_hrtimer ?
+ (ARRAY_SIZE(properties) / 2) :
+ ((ARRAY_SIZE(properties) / 2) - 1)),
.properties_ptr = to_user_pointer(properties),
};
uint8_t buf[1024 * 1024];
@@ -2122,15 +2139,16 @@ test_polling(void)
int n_extra_iterations = 0;

/* It's a bit tricky to put a lower limit here, but we expect a
- * relatively low latency for seeing reports, while we don't currently
- * give any control over this in the api.
+ * relatively low latency for seeing reports.
*
- * We assume a maximum latency of 6 millisecond to deliver a POLLIN and
- * read() after a new sample is written (46ms per iteration) considering
- * the knowledge that that the driver uses a 200Hz hrtimer (5ms period)
- * to check for data and giving some time to read().
+ * We assume a maximum latency of kernel_hrtimer + some margin
+ * to deliver a POLLIN and read() after a new sample is
+ * written (40ms + hrtimer + margin per iteration) considering
+ * the knowledge that that the driver uses a 200Hz hrtimer
+ * (5ms period) to check for data and giving some time to
+ * read().
*/
- int min_iterations = (test_duration_ns / (oa_period + 6000000ull));
+ int min_iterations = (test_duration_ns / (oa_period + (kernel_hrtimer + kernel_hrtimer / 5)));
int64_t start, end;
int n = 0;

@@ -2138,8 +2156,9 @@ test_polling(void)

times(&start_times);

- igt_debug("tick length = %dns, test duration = %"PRIu64"ns, min iter. = %d, max iter. = %d\n",
- (int)tick_ns, test_duration_ns,
+ igt_debug("tick length = %dns, oa period = %s, "
+ "test duration = %"PRIu64"ns, min iter. = %d, max iter. = %d\n",
+ (int)tick_ns, pretty_print_oa_period(oa_period), test_duration_ns,
min_iterations, max_iterations);

/* In the loop we perform blocking polls while the HW is sampling at
@@ -4507,6 +4526,23 @@ test_sysctl_defaults(void)
igt_assert_eq(max_freq, 100000);
}

+static int i915_perf_revision(int fd)
+{
+ drm_i915_getparam_t gp;
+ int value = 1, ret;
+
+ gp.param = I915_PARAM_PERF_REVISION;
+ gp.value = &value;
+ ret = igt_ioctl(drm_fd, DRM_IOCTL_I915_GETPARAM, &gp);
+ if (ret == -1) {
+ /* If the param is missing, consider version 1. */
+ igt_assert_eq(errno, EINVAL);
+ return 1;
+ }
+
+ return value;
+}
+
igt_main
{
igt_fixture {
@@ -4589,11 +4625,43 @@ igt_main
igt_subtest("enable-disable")
test_enable_disable();

- igt_subtest("blocking")
- test_blocking();
+ igt_describe("Test blocking read with default hrtimer frequency");
+ igt_subtest("blocking") {
+ test_blocking(40 * 1000 * 1000 /* 40ms oa period */,
+ false /* set_kernel_hrtimer */,
+ 5 * 1000 * 1000 /* default 5ms/200Hz hrtimer */);
+ }
+
+ igt_describe("Test blocking read with different hrtimer frequencies");
+ igt_subtest("blocking-parameterized") {
+ igt_require(i915_perf_revision(drm_fd) >= 4);
+
+ test_blocking(10 * 1000 * 1000 /* 10ms oa period */,
+ true /* set_kernel_hrtimer */,
+ 40 * 1000 * 1000 /* default 40ms hrtimer */);
+ test_blocking(500 * 1000 /* 500us oa period */,
+ true /* set_kernel_hrtimer */,
+ 2 * 1000 * 1000 /* default 2ms hrtimer */);
+ }

- igt_subtest("polling")
- test_polling();
+ igt_describe("Test polled read with default hrtimer frequency");
+ igt_subtest("polling") {
+ test_polling(40 * 1000 * 1000 /* 40ms oa period */,
+ false /* set_kernel_hrtimer */,
+ 5 * 1000 * 1000 /* default 5ms/200Hz hrtimer */);
+ }
+
+ igt_describe("Test polled read with different hrtimer frequencies");
+ igt_subtest("polling-parameterized") {
+ igt_require(i915_perf_revision(drm_fd) >= 4);
+
+ test_polling(10 * 1000 * 1000 /* 10ms oa period */,
+ true /* set_kernel_hrtimer */,
+ 40 * 1000 * 1000 /* default 40ms hrtimer */);
+ test_polling(500 * 1000 /* 500us oa period */,
+ true /* set_kernel_hrtimer */,
+ 2 * 1000 * 1000 /* default 2ms hrtimer */);
+ }

igt_subtest("short-reads")
test_short_reads();
--
2.20.1