From cd3862dc6e89817dbeefa02881400da926ffceeb Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Mon, 13 Feb 2017 17:15:27 +0000 Subject: [PATCH] drm/i915: Live testing of empty requests 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 Reviewed-by: Joonas Lahtinen Link: http://patchwork.freedesktop.org/patch/msgid/20170213171558.20942-16-chris@chris-wilson.co.uk --- .../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 e946488d6af2..9d056a86723d 100644 --- a/drivers/gpu/drm/i915/selftests/i915_gem_request.c +++ b/drivers/gpu/drm/i915/selftests/i915_gem_request.c @@ -338,6 +338,160 @@ out_unlock: 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; @@ -658,6 +812,7 @@ 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); } -- 2.20.1