[igt-dev] [PATCH igt] tests: Add a random load generator

[Chris Wilson]

Apply a random load to one or all engines in order to apply stress to
RPS as it tries to constantly adjust the GPU frequency to meet the
changing workload.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 tests/Makefile.sources |   1 +
 tests/gem_exec_load.c  | 124 +++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 125 insertions(+)
 create mode 100644 tests/gem_exec_load.c

diff --git a/tests/Makefile.sources b/tests/Makefile.sources
index 6d3857949..5c6242bca 100644
--- a/tests/Makefile.sources
+++ b/tests/Makefile.sources
@@ -83,6 +83,7 @@ TESTS_progs = \
 	gem_exec_gttfill \
 	gem_exec_latency \
 	gem_exec_lut_handle \
+	gem_exec_load \
 	gem_exec_nop \
 	gem_exec_parallel \
 	gem_exec_params \
diff --git a/tests/gem_exec_load.c b/tests/gem_exec_load.c
new file mode 100644
index 000000000..d3618f6c0
--- /dev/null
+++ b/tests/gem_exec_load.c
@@ -0,0 +1,124 @@
+/*
+ * Copyright © 2018 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#include "igt.h"
+#include "igt_rand.h"
+#include "igt_sysfs.h"
+
+IGT_TEST_DESCRIPTION("Apply a random load to each engine");
+
+static inline uint32_t randmax(uint32_t *state, uint32_t ep_ro)
+{
+	return (uint64_t)hars_petruska_f54_1_random(state) * ep_ro >> 32;
+}
+
+static void one(int fd, unsigned int engine, int scale, unsigned int timeout)
+{
+	struct timespec tv = {};
+	uint32_t prng = engine;
+	igt_spin_t *spin[2] = {};
+	unsigned int max;
+	int sysfs;
+
+	sysfs = igt_sysfs_open(fd, NULL);
+
+	max = sysfs < 0 ? 1 : igt_sysfs_get_u32(sysfs, "gt_max_freq_mhz");
+
+	do {
+		/*
+		 * For every second, we randomly assign a desire % busyness
+		 * and the frequency with which to submit a batch, defining
+		 * a pulse-width modulation (pwm).
+		 */
+		unsigned int pwm = randmax(&prng, 1000);
+		unsigned int load = randmax(&prng, pwm / scale);
+		const unsigned int interval = 1e6 / pwm;
+		unsigned int cur =
+			sysfs < 0 ? 1 : igt_sysfs_get_u32(sysfs, "gt_cur_freq_mhz");
+
+		while (pwm--) {
+			if (randmax(&prng, pwm * cur) <= load * max) {
+				spin[1] = __igt_spin_batch_new(fd, 0, engine, 0);
+				load--;
+			}
+			igt_spin_batch_free(fd, spin[0]);
+			spin[0] = spin[1];
+			spin[1] = NULL;
+
+			usleep(interval);
+		}
+	} while (igt_seconds_elapsed(&tv) < timeout);
+	igt_spin_batch_free(fd, spin[0]);
+
+	close(sysfs);
+}
+
+static void all(int fd, unsigned int timeout)
+{
+	unsigned int engines[16];
+	unsigned int nengine;
+	unsigned int engine;
+
+	nengine = 0;
+	for_each_engine(fd, engine)
+		engines[nengine++] = engine;
+	igt_require(nengine > 1);
+
+	for (unsigned int n = 0; n < nengine; n++)
+		igt_fork(child, 1)
+			one(fd, engines[n], nengine/2, timeout);
+	igt_waitchildren();
+}
+
+igt_main
+{
+	const struct intel_execution_engine *e;
+	int fd = -1;
+
+	igt_skip_on_simulation();
+
+	igt_fixture {
+		fd = drm_open_driver(DRIVER_INTEL);
+		igt_require_gem(fd);
+		igt_fork_hang_detector(fd);
+	}
+
+	for (e = intel_execution_engines; e->name; e++) {
+		/* default exec-id is purely symbolic */
+		if (e->exec_id == 0)
+			continue;
+
+		igt_subtest_f("%s", e->name) {
+			gem_require_ring(fd, e->exec_id | e->flags);
+			one(fd, e->exec_id | e->flags, 1, 150);
+		}
+	}
+
+	igt_subtest("all")
+		all(fd, 900);
+
+	igt_fixture {
+		igt_stop_hang_detector();
+		close(fd);
+	}
+}
-- 
2.15.1