On Tue, 2020-05-12 at 18:19 +0100, Chris Wilson wrote:
> Our 'headless' subtest requires fairly precise measurements to determine
> the impact of the dmc upon request latency. The test cannot be effective
> if we cannot execute requests quickly, so add a very short pre-pass to
> check the test requirements. For this we want to specify the baseline
> measurement timeout in milliseconds, allowing us to speed up our other
> baseline measurements elsewhere as well.
>
> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Reviewed-by: Janusz Krzysztofik <janusz.krzysztofik@xxxxxxxxxxxxxxx>
Thanks,
Janusz
> ---
> tests/i915/gem_exec_nop.c | 29 +++++++++++++++++------------
> 1 file changed, 17 insertions(+), 12 deletions(-)
>
> diff --git a/tests/i915/gem_exec_nop.c b/tests/i915/gem_exec_nop.c
> index 4051e0fd7..21a937c83 100644
> --- a/tests/i915/gem_exec_nop.c
> +++ b/tests/i915/gem_exec_nop.c
> @@ -64,7 +64,7 @@ static double elapsed(const struct timespec *start, const struct timespec *end)
>
> static double nop_on_ring(int fd, uint32_t handle,
> const struct intel_execution_engine2 *e,
> - int timeout,
> + int timeout_ms,
> unsigned long *out)
> {
> struct drm_i915_gem_execbuffer2 execbuf;
> @@ -94,7 +94,7 @@ static double nop_on_ring(int fd, uint32_t handle,
> count++;
>
> clock_gettime(CLOCK_MONOTONIC, &now);
> - } while (elapsed(&start, &now) < timeout);
> + } while (elapsed(&start, &now) < timeout_ms * 1e-3);
> igt_assert_eq(intel_detect_and_clear_missed_interrupts(fd), 0);
>
> *out = count;
> @@ -348,14 +348,15 @@ static void single(int fd, uint32_t handle,
> double time;
> unsigned long count;
>
> - time = nop_on_ring(fd, handle, e, 20, &count);
> + time = nop_on_ring(fd, handle, e, 20000, &count);
> igt_info("%s: %'lu cycles: %.3fus\n",
> e->name, count, time*1e6 / count);
> }
>
> static double
> stable_nop_on_ring(int fd, uint32_t handle,
> - const struct intel_execution_engine2 *e, int timeout,
> + const struct intel_execution_engine2 *e,
> + int timeout_ms,
> int reps)
> {
> igt_stats_t s;
> @@ -370,7 +371,7 @@ stable_nop_on_ring(int fd, uint32_t handle,
> unsigned long count;
> double time;
>
> - time = nop_on_ring(fd, handle, e, timeout, &count);
> + time = nop_on_ring(fd, handle, e, timeout_ms, &count);
> igt_stats_push_float(&s, time / count);
> }
>
> @@ -390,9 +391,10 @@ static void headless(int fd, uint32_t handle,
> const struct intel_execution_engine2 *e)
> {
> unsigned int nr_connected = 0;
> + double n_display, n_headless;
> drmModeConnector *connector;
> + unsigned long count;
> drmModeRes *res;
> - double n_display, n_headless;
>
> res = drmModeGetResources(fd);
> igt_require(res);
> @@ -409,8 +411,11 @@ static void headless(int fd, uint32_t handle,
> /* set graphics mode to prevent blanking */
> kmstest_set_vt_graphics_mode();
>
> + nop_on_ring(fd, handle, e, 10, &count);
> + igt_require_f(count > 100, "submillisecond precision required\n");
> +
> /* benchmark nops */
> - n_display = stable_nop_on_ring(fd, handle, e, 1, 5);
> + n_display = stable_nop_on_ring(fd, handle, e, 500, 5);
> igt_info("With one display connected: %.2fus\n",
> n_display * 1e6);
>
> @@ -418,7 +423,7 @@ static void headless(int fd, uint32_t handle,
> kmstest_unset_all_crtcs(fd, res);
>
> /* benchmark nops again */
> - n_headless = stable_nop_on_ring(fd, handle, e, 1, 5);
> + n_headless = stable_nop_on_ring(fd, handle, e, 500, 5);
> igt_info("Without a display connected (headless): %.2fus\n",
> n_headless * 1e6);
>
> @@ -444,7 +449,7 @@ static void parallel(int fd, uint32_t handle, int timeout)
> engines[nengine] = e->flags;
> names[nengine++] = strdup(e->name);
>
> - time = nop_on_ring(fd, handle, e, 1, &count) / count;
> + time = nop_on_ring(fd, handle, e, 250, &count) / count;
> sum += time;
> igt_debug("%s: %.3fus\n", e->name, 1e6*time);
> }
> @@ -506,7 +511,7 @@ static void independent(int fd, uint32_t handle, int timeout)
> engines[nengine] = e->flags;
> names[nengine++] = strdup(e->name);
>
> - time = nop_on_ring(fd, handle, e, 1, &count) / count;
> + time = nop_on_ring(fd, handle, e, 250, &count) / count;
> sum += time;
> igt_debug("%s: %.3fus\n", e->name, 1e6*time);
> }
> @@ -626,7 +631,7 @@ static void series(int fd, uint32_t handle, int timeout)
>
> nengine = 0;
> __for_each_physical_engine(fd, e) {
> - time = nop_on_ring(fd, handle, e, 1, &count) / count;
> + time = nop_on_ring(fd, handle, e, 250, &count) / count;
> if (time > max) {
> name = e->name;
> max = time;
> @@ -705,7 +710,7 @@ static void sequential(int fd, uint32_t handle, unsigned flags, int timeout)
> __for_each_physical_engine(fd, e) {
> unsigned long count;
>
> - time = nop_on_ring(fd, handle, e, 1, &count) / count;
> + time = nop_on_ring(fd, handle, e, 250, &count) / count;
> sum += time;
> igt_debug("%s: %.3fus\n", e->name, 1e6*time);
>
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