[igt-dev] [PATCH i-g-t] i915: Exercise I915_CONTEXT_PARAM_RINGSIZE

Chris Wilson chris at chris-wilson.co.uk
Fri Feb 21 10:08:00 UTC 2020


I915_CONTEXT_PARAM_RINGSIZE specifies how large to create the command
ringbuffer for logical ring contects. This directly affects the number
of batches userspace can submit before blocking waiting for space.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 tests/Makefile.sources        |   3 +
 tests/i915/gem_ctx_ringsize.c | 350 ++++++++++++++++++++++++++++++++++
 tests/meson.build             |   1 +
 3 files changed, 354 insertions(+)
 create mode 100644 tests/i915/gem_ctx_ringsize.c

diff --git a/tests/Makefile.sources b/tests/Makefile.sources
index b87d6333b..76cf99da5 100644
--- a/tests/Makefile.sources
+++ b/tests/Makefile.sources
@@ -163,6 +163,9 @@ gem_ctx_param_SOURCES = i915/gem_ctx_param.c
 TESTS_progs += gem_ctx_persistence
 gem_ctx_persistence_SOURCES = i915/gem_ctx_persistence.c
 
+TESTS_progs += gem_ctx_ringsize
+gem_ctx_ringsize_SOURCES = i915/gem_ctx_ringsize.c
+
 TESTS_progs += gem_ctx_shared
 gem_ctx_shared_SOURCES = i915/gem_ctx_shared.c
 
diff --git a/tests/i915/gem_ctx_ringsize.c b/tests/i915/gem_ctx_ringsize.c
new file mode 100644
index 000000000..54bdc639b
--- /dev/null
+++ b/tests/i915/gem_ctx_ringsize.c
@@ -0,0 +1,350 @@
+/*
+ * Copyright © 2019 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 <errno.h>
+#include <fcntl.h>
+#include <inttypes.h>
+#include <math.h>
+#include <sys/ioctl.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include "drmtest.h" /* gem_quiescent_gpu()! */
+#include "i915/gem_context.h"
+#include "i915/gem_engine_topology.h"
+#include "ioctl_wrappers.h" /* gem_wait()! */
+#include "sw_sync.h"
+
+#define I915_CONTEXT_PARAM_RINGSIZE 0xc
+
+static bool has_ringsize(int i915)
+{
+	struct drm_i915_gem_context_param p = {
+		.param = I915_CONTEXT_PARAM_RINGSIZE,
+	};
+
+	return __gem_context_get_param(i915, &p) == 0;
+}
+
+static void test_idempotent(int i915)
+{
+	struct drm_i915_gem_context_param p = {
+		.param = I915_CONTEXT_PARAM_RINGSIZE,
+	};
+	uint32_t saved;
+
+	/*
+	 * Simple test to verify that we are able to read back the same
+	 * value as we set.
+	 */
+
+	gem_context_get_param(i915, &p);
+	saved = p.value;
+
+	for (uint32_t x = 1 << 12; x <= 128 << 12; x <<= 1) {
+		p.value = x;
+		gem_context_set_param(i915, &p);
+		gem_context_get_param(i915, &p);
+		igt_assert_eq_u32(p.value, x);
+	}
+
+	p.value = saved;
+	gem_context_set_param(i915, &p);
+}
+
+static void test_invalid(int i915)
+{
+	struct drm_i915_gem_context_param p = {
+		.param = I915_CONTEXT_PARAM_RINGSIZE,
+	};
+	uint64_t invalid[] = {
+		0, 1, 4095, 4097, 8191, 8193,
+		/* upper limit may be HW dependent, atm it is 512KiB */
+		(512 << 10) - 1, (512 << 10) + 1,
+		-1, -1u
+	};
+	uint32_t saved;
+
+	/*
+	 * The HW only accepts certain aligned values and so we reject
+	 * any invalid sizes specified by the user.
+	 *
+	 * Currently, the HW only accepts 4KiB - 512KiB in 4K increments,
+	 * and is unlikely to ever accept smaller.
+	 */
+
+	gem_context_get_param(i915, &p);
+	saved = p.value;
+
+	for (int i = 0; i < ARRAY_SIZE(invalid); i++) {
+		p.value = invalid[i];
+		igt_assert_eq(__gem_context_set_param(i915, &p), -EINVAL);
+		gem_context_get_param(i915, &p);
+		igt_assert_eq_u64(p.value, saved);
+	}
+}
+
+static int create_ext_ioctl(int i915,
+			    struct drm_i915_gem_context_create_ext *arg)
+{
+	int err;
+
+	err = 0;
+	if (igt_ioctl(i915, DRM_IOCTL_I915_GEM_CONTEXT_CREATE_EXT, arg)) {
+		err = -errno;
+		igt_assume(err);
+	}
+
+	errno = 0;
+	return err;
+}
+
+static void test_create(int i915)
+{
+	struct drm_i915_gem_context_create_ext_setparam p = {
+		.base = {
+			.name = I915_CONTEXT_CREATE_EXT_SETPARAM,
+			.next_extension = 0, /* end of chain */
+		},
+		.param = {
+			.param = I915_CONTEXT_PARAM_RINGSIZE,
+			.value = 512 << 10,
+		}
+	};
+	struct drm_i915_gem_context_create_ext create = {
+		.flags = I915_CONTEXT_CREATE_FLAGS_USE_EXTENSIONS,
+		.extensions = to_user_pointer(&p),
+	};
+
+	/*
+	 * Check that the ringsize parameter is used during context constuction.
+	 */
+
+	igt_assert_eq(create_ext_ioctl(i915, &create),  0);
+
+	p.param.ctx_id = create.ctx_id;
+	p.param.value = 0;
+	gem_context_get_param(i915, &p.param);
+	igt_assert_eq(p.param.value, 512 << 10);
+
+	gem_context_destroy(i915, create.ctx_id);
+}
+
+static void test_clone(int i915)
+{
+	struct drm_i915_gem_context_create_ext_setparam p = {
+		.base = {
+			.name = I915_CONTEXT_CREATE_EXT_SETPARAM,
+			.next_extension = 0, /* end of chain */
+		},
+		.param = {
+			.param = I915_CONTEXT_PARAM_RINGSIZE,
+			.value = 512 << 10,
+		}
+	};
+	struct drm_i915_gem_context_create_ext create = {
+		.flags = I915_CONTEXT_CREATE_FLAGS_USE_EXTENSIONS,
+		.extensions = to_user_pointer(&p),
+	};
+
+	/*
+	 * Check that the ringsize is copied across during context cloning.
+	 */
+
+	igt_assert_eq(create_ext_ioctl(i915, &create),  0);
+
+	p.param.ctx_id = gem_context_clone(i915, create.ctx_id,
+					   I915_CONTEXT_CLONE_ENGINES, 0);
+	igt_assert_neq(p.param.ctx_id, create.ctx_id);
+	gem_context_destroy(i915, create.ctx_id);
+
+	p.param.value = 0;
+	gem_context_get_param(i915, &p.param);
+	igt_assert_eq(p.param.value, 512 << 10);
+
+	gem_context_destroy(i915, p.param.ctx_id);
+}
+
+static int __execbuf(int i915, struct drm_i915_gem_execbuffer2 *execbuf)
+{
+	int err;
+
+	err = 0;
+	if (ioctl(i915, DRM_IOCTL_I915_GEM_EXECBUFFER2, execbuf)) {
+		err = -errno;
+		igt_assume(err);
+	}
+
+	errno = 0;
+	return err;
+}
+
+static uint32_t __batch_create(int i915, uint32_t offset)
+{
+	const uint32_t bbe = 0xa << 23;
+	uint32_t handle;
+
+	handle = gem_create(i915, offset + sizeof(bbe));
+	gem_write(i915, handle, offset, &bbe, sizeof(bbe));
+
+	return handle;
+}
+
+static uint32_t batch_create(int i915)
+{
+	return __batch_create(i915, 0);
+}
+
+static unsigned int measure_inflight(int i915, unsigned int engine, int timeout)
+{
+	IGT_CORK_FENCE(cork);
+	struct drm_i915_gem_exec_object2 obj = {
+		.handle = batch_create(i915)
+	};
+	struct drm_i915_gem_execbuffer2 execbuf = {
+		.buffers_ptr = to_user_pointer(&obj),
+		.buffer_count = 1,
+		.flags = engine | I915_EXEC_FENCE_IN,
+		.rsvd2 = igt_cork_plug(&cork, i915),
+	};
+	unsigned int count;
+	int err;
+
+	fcntl(i915, F_SETFL, fcntl(i915, F_GETFL) | O_NONBLOCK);
+	igt_set_timeout(timeout, "execbuf blocked!");
+
+	gem_execbuf(i915, &execbuf);
+	for (count = 1; (err = __execbuf(i915, &execbuf)) == 0; count++)
+		;
+	igt_assert_eq(err, -EWOULDBLOCK);
+	close(execbuf.rsvd2);
+
+	igt_reset_timeout();
+	fcntl(i915, F_SETFL, fcntl(i915, F_GETFL) & ~O_NONBLOCK);
+
+	igt_cork_unplug(&cork);
+	gem_close(i915, obj.handle);
+
+	return count;
+}
+
+static void test_resize(int i915,
+			const struct intel_execution_engine2 *e,
+			void *data)
+#define IDLE (1 << 0)
+#define as_pointer(x) (void *)(uintptr_t)(x)
+{
+	struct drm_i915_gem_context_param p = {
+		.param = I915_CONTEXT_PARAM_RINGSIZE,
+	};
+	unsigned long flags = (uintptr_t)data;
+	unsigned int prev[2] = {};
+	uint64_t elapsed;
+	uint32_t saved;
+
+	/*
+	 * The ringsize directly affects the number of batches we can have
+	 * inflight -- when we run out of room in the ring, the client is
+	 * blocked (or if O_NONBLOCK is specified, -EWOULDBLOCK is reported).
+	 * The kernel throttles the client when they enter the last 4KiB page,
+	 * so as we double the size of the ring, we nearly double the number
+	 * of requests we can fit as 2^n-1: i.e 0, 1, 3, 7, 15, 31 pages.
+	 */
+
+	gem_context_get_param(i915, &p);
+	saved = p.value;
+
+	elapsed = 0;
+	gem_quiescent_gpu(i915);
+	for (p.value = 1 << 12; p.value <= 128 << 12; p.value <<= 1) {
+		struct timespec tv = {};
+		unsigned int count;
+
+		gem_context_set_param(i915, &p);
+
+		igt_nsec_elapsed(&tv);
+		count = measure_inflight(i915, e->flags, 1 + ceil(2 * elapsed*1e-9));
+		elapsed = igt_nsec_elapsed(&tv);
+
+		igt_info("%s: %llx -> %d\n", e->name, p.value, count);
+		igt_assert(count > 3 * (prev[1] - prev[0]) / 4 + prev[1]);
+		if (flags & IDLE)
+			gem_quiescent_gpu(i915);
+
+		prev[0] = prev[1];
+		prev[1] = count;
+	}
+	gem_quiescent_gpu(i915);
+
+	p.value = saved;
+	gem_context_set_param(i915, &p);
+}
+
+static void gem_test_each_engine(int i915, const char *name,
+				 void (*fn)(int i915,
+					    const struct intel_execution_engine2 *e,
+					    void *data),
+				 void *data)
+{
+	const struct intel_execution_engine2 *e;
+
+	igt_subtest_with_dynamic(name) {
+		__for_each_physical_engine(i915, e) {
+			igt_dynamic_f("%s", e->name)
+				fn(i915, e, data);
+		}
+	}
+}
+
+igt_main
+{
+	const struct intel_execution_engine2 *e;
+	int i915;
+
+	igt_fixture {
+		i915 = drm_open_driver(DRIVER_INTEL);
+		igt_require_gem(i915);
+
+		igt_require(has_ringsize(i915));
+	}
+
+	igt_subtest("idempotent")
+		test_idempotent(i915);
+
+	igt_subtest("invalid")
+		test_invalid(i915);
+
+	igt_subtest("create")
+		test_create(i915);
+	igt_subtest("clone")
+		test_clone(i915);
+
+	gem_test_each_engine(i915, "idle", test_resize, as_pointer(IDLE));
+	gem_test_each_engine(i915, "active", test_resize, 0);
+
+	/* XXX ctx->engines[]? Clone (above) should be enough */
+
+	igt_fixture {
+		close(i915);
+	}
+}
diff --git a/tests/meson.build b/tests/meson.build
index fa0103e3a..c940e85b0 100644
--- a/tests/meson.build
+++ b/tests/meson.build
@@ -124,6 +124,7 @@ i915_progs = [
 	'gem_ctx_isolation',
 	'gem_ctx_param',
 	'gem_ctx_persistence',
+	'gem_ctx_ringsize',
 	'gem_ctx_shared',
 	'gem_ctx_switch',
 	'gem_ctx_thrash',
-- 
2.25.1



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