Primarily to emphasize the difference between just advancing the
breadcrumb using a bare request and the overhead of dispatching an
execbuffer.
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/selftests/i915_gem_request.c | 155 ++++++++++++++++++++++
1 file changed, 155 insertions(+)
diff --git a/drivers/gpu/drm/i915/selftests/i915_gem_request.c b/drivers/gpu/drm/i915/selftests/i915_gem_request.c
index f9c171d1a05b..92fa55bd68c8 100644
--- a/drivers/gpu/drm/i915/selftests/i915_gem_request.c
+++ b/drivers/gpu/drm/i915/selftests/i915_gem_request.c
@@ -301,6 +301,160 @@ static int live_nop_request(void *arg)
return err;
}
+static struct i915_vma *empty_batch(struct drm_i915_private *i915)
+{
+ struct drm_i915_gem_object *obj;
+ struct i915_vma *vma;
+ u32 *cmd;
+ int err;
+
+ obj = i915_gem_object_create_internal(i915, PAGE_SIZE);
+ if (IS_ERR(obj))
+ return ERR_CAST(obj);
+
+ cmd = i915_gem_object_pin_map(obj, I915_MAP_WB);
+ if (IS_ERR(cmd)) {
+ err = PTR_ERR(cmd);
+ goto err;
+ }
+ *cmd = MI_BATCH_BUFFER_END;
+ i915_gem_object_unpin_map(obj);
+
+ err = i915_gem_object_set_to_gtt_domain(obj, false);
+ if (err)
+ goto err;
+
+ vma = i915_vma_instance(obj, &i915->ggtt.base, NULL);
+ if (IS_ERR(vma)) {
+ err = PTR_ERR(vma);
+ goto err;
+ }
+
+ err = i915_vma_pin(vma, 0, 0, PIN_USER | PIN_GLOBAL);
+ if (err)
+ goto err;
+
+ return vma;
+
+err:
+ i915_gem_object_put(obj);
+ return ERR_PTR(err);
+}
+
+static struct drm_i915_gem_request *
+empty_request(struct intel_engine_cs *engine,
+ struct i915_vma *batch)
+{
+ struct drm_i915_gem_request *request;
+ int err;
+
+ request = i915_gem_request_alloc(engine,
+ engine->i915->kernel_context);
+ if (IS_ERR(request))
+ return request;
+
+ err = engine->emit_flush(request, EMIT_INVALIDATE);
+ if (err)
+ goto out_request;
+
+ err = i915_switch_context(request);
+ if (err)
+ goto out_request;
+
+ err = engine->emit_bb_start(request,
+ batch->node.start,
+ batch->node.size,
+ I915_DISPATCH_SECURE);
+ if (err)
+ goto out_request;
+
+out_request:
+ __i915_add_request(request, err == 0);
+ return err ? ERR_PTR(err) : request;
+}
+
+static int live_empty_request(void *arg)
+{
+ struct drm_i915_private *i915 = arg;
+ struct intel_engine_cs *engine;
+ struct live_test t;
+ struct i915_vma *batch;
+ unsigned int id;
+ int err = 0;
+
+ /* Submit various sized batches of empty requests, to each engine
+ * (individually), and wait for the batch to complete. We can check
+ * the overhead of submitting requests to the hardware.
+ */
+
+ mutex_lock(&i915->drm.struct_mutex);
+
+ batch = empty_batch(i915);
+ if (IS_ERR(batch)) {
+ err = PTR_ERR(batch);
+ goto out_unlock;
+ }
+
+ for_each_engine(engine, i915, id) {
+ IGT_TIMEOUT(end_time);
+ struct drm_i915_gem_request *request;
+ unsigned long n, prime;
+ ktime_t times[2] = {};
+
+ err = begin_live_test(&t, i915, __func__, engine->name);
+ if (err)
+ goto out_batch;
+
+ /* Warmup / preload */
+ request = empty_request(engine, batch);
+ if (IS_ERR(request)) {
+ err = PTR_ERR(request);
+ goto out_batch;
+ }
+ i915_wait_request(request,
+ I915_WAIT_LOCKED,
+ MAX_SCHEDULE_TIMEOUT);
+
+ for_each_prime_number_from(prime, 1, 8192) {
+ times[1] = ktime_get_raw();
+
+ for (n = 0; n < prime; n++) {
+ request = empty_request(engine, batch);
+ if (IS_ERR(request)) {
+ err = PTR_ERR(request);
+ goto out_batch;
+ }
+ }
+ i915_wait_request(request,
+ I915_WAIT_LOCKED,
+ MAX_SCHEDULE_TIMEOUT);
+
+ times[1] = ktime_sub(ktime_get_raw(), times[1]);
+ if (prime == 1)
+ times[0] = times[1];
+
+ if (__igt_timeout(end_time, NULL))
+ break;
+ }
+
+ err = end_live_test(&t);
+ if (err)
+ goto out_batch;
+
+ pr_info("Batch latencies on %s: 1 = %lluns, %lu = %lluns\n",
+ engine->name,
+ ktime_to_ns(times[0]),
+ prime, div64_u64(ktime_to_ns(times[1]), prime));
+ }
+
+out_batch:
+ i915_vma_unpin(batch);
+ i915_vma_put(batch);
+out_unlock:
+ mutex_unlock(&i915->drm.struct_mutex);
+ return err;
+}
+
static struct i915_vma *recursive_batch(struct drm_i915_private *i915)
{
struct i915_gem_context *ctx = i915->kernel_context;
@@ -615,6 +769,7 @@ int i915_gem_request_live_selftests(struct drm_i915_private *i915)
SUBTEST(live_nop_request),
SUBTEST(live_all_engines),
SUBTEST(live_sequential_engines),
+ SUBTEST(live_empty_request),
};
return i915_subtests(tests, i915);
}
--
2.11.0
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