As a topological sort, we expect it to run in linear graph time,
O(V+E). In removing the recursion, it is no longer a DFS but rather a
BFS, and performs as O(VE). Let's demonstrate how bad this is with a few
examples, and build a few test cases to verify a potential fix.
Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk>
---
drivers/gpu/drm/i915/i915_scheduler.c | 4 +
.../drm/i915/selftests/i915_live_selftests.h | 1 +
.../drm/i915/selftests/i915_perf_selftests.h | 1 +
.../gpu/drm/i915/selftests/i915_scheduler.c | 530 ++++++++++++++++++
4 files changed, 536 insertions(+)
create mode 100644 drivers/gpu/drm/i915/selftests/i915_scheduler.c
diff --git a/drivers/gpu/drm/i915/i915_scheduler.c
b/drivers/gpu/drm/i915/i915_scheduler.c
index 45e000c257db..3c1a0b001746 100644
--- a/drivers/gpu/drm/i915/i915_scheduler.c
+++ b/drivers/gpu/drm/i915/i915_scheduler.c
@@ -565,6 +565,10 @@ void i915_sched_node_retire(struct i915_sched_node *node)
spin_unlock_irq(&node->lock);
}
+#if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
+#include "selftests/i915_scheduler.c"
+#endif
+
static void i915_global_scheduler_shrink(void)
{
kmem_cache_shrink(global.slab_dependencies);
diff --git a/drivers/gpu/drm/i915/selftests/i915_live_selftests.h
b/drivers/gpu/drm/i915/selftests/i915_live_selftests.h
index a92c0e9b7e6b..2200a5baa68e 100644
--- a/drivers/gpu/drm/i915/selftests/i915_live_selftests.h
+++ b/drivers/gpu/drm/i915/selftests/i915_live_selftests.h
@@ -26,6 +26,7 @@ selftest(gt_mocs, intel_mocs_live_selftests)
selftest(gt_pm, intel_gt_pm_live_selftests)
selftest(gt_heartbeat, intel_heartbeat_live_selftests)
selftest(requests, i915_request_live_selftests)
+selftest(scheduler, i915_scheduler_live_selftests)
selftest(active, i915_active_live_selftests)
selftest(objects, i915_gem_object_live_selftests)
selftest(mman, i915_gem_mman_live_selftests)
diff --git a/drivers/gpu/drm/i915/selftests/i915_perf_selftests.h
b/drivers/gpu/drm/i915/selftests/i915_perf_selftests.h
index c2389f8a257d..137e35283fee 100644
--- a/drivers/gpu/drm/i915/selftests/i915_perf_selftests.h
+++ b/drivers/gpu/drm/i915/selftests/i915_perf_selftests.h
@@ -17,5 +17,6 @@
*/
selftest(engine_cs, intel_engine_cs_perf_selftests)
selftest(request, i915_request_perf_selftests)
+selftest(scheduler, i915_scheduler_perf_selftests)
selftest(blt, i915_gem_object_blt_perf_selftests)
selftest(region, intel_memory_region_perf_selftests)
diff --git a/drivers/gpu/drm/i915/selftests/i915_scheduler.c
b/drivers/gpu/drm/i915/selftests/i915_scheduler.c
new file mode 100644
index 000000000000..98d29fa8f5f8
--- /dev/null
+++ b/drivers/gpu/drm/i915/selftests/i915_scheduler.c
@@ -0,0 +1,530 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright © 2020 Intel Corporation
+ */
+
+#include "i915_selftest.h"
+
+#include "gt/intel_context.h"
+#include "gt/selftest_engine_heartbeat.h"
+#include "selftests/igt_spinner.h"
+
+static void scheduling_disable(struct intel_engine_cs *engine)
+{
+ engine->props.preempt_timeout_ms = 0;
+ engine->props.timeslice_duration_ms = 0;
+
+ st_engine_heartbeat_disable(engine);
+}
+
+static void scheduling_enable(struct intel_engine_cs *engine)
+{
+ st_engine_heartbeat_enable(engine);
+
+ engine->props.preempt_timeout_ms =
+ engine->defaults.preempt_timeout_ms;
+ engine->props.timeslice_duration_ms =
+ engine->defaults.timeslice_duration_ms;
+}
+
+static int first_engine(struct drm_i915_private *i915,
+ int (*chain)(struct intel_engine_cs *engine,
+ unsigned long param,
+ void (*fn)(struct i915_request *rq,
+ unsigned long v,
+ unsigned long e)),
+ unsigned long param,
+ void (*fn)(struct i915_request *rq,
+ unsigned long v, unsigned long e))
+{
+ struct intel_engine_cs *engine;
+
+ for_each_uabi_engine(engine, i915) {
+ if (!intel_engine_has_scheduler(engine))
+ continue;
+
+ return chain(engine, param, fn);
+ }
+
+ return 0;
+}
+
+static int all_engines(struct drm_i915_private *i915,
+ int (*chain)(struct intel_engine_cs *engine,
+ unsigned long param,
+ void (*fn)(struct i915_request *rq,
+ unsigned long v,
+ unsigned long e)),
+ unsigned long param,
+ void (*fn)(struct i915_request *rq,
+ unsigned long v, unsigned long e))
+{
+ struct intel_engine_cs *engine;
+ int err;
+
+ for_each_uabi_engine(engine, i915) {
+ if (!intel_engine_has_scheduler(engine))
+ continue;
+
+ err = chain(engine, param, fn);
+ if (err)
+ return err;
+ }
+
+ return 0;
+}
+
+static bool check_context_order(struct intel_engine_cs *engine)
+{
+ u64 last_seqno, last_context;
+ unsigned long count;
+ bool result = false;
+ struct rb_node *rb;
+ int last_prio;
+
+ /* We expect the execution order to follow ascending fence-context */
+ spin_lock_irq(&engine->active.lock);
+
+ count = 0;
+ last_context = 0;
+ for (rb = rb_first_cached(&engine->execlists.queue); rb; rb =
rb_next(rb)) {
+ struct i915_priolist *p = rb_entry(rb, typeof(*p), node);
+ struct i915_request *rq;
+
+ priolist_for_each_request(rq, p) {
+ if (rq->fence.context < last_context ||
+ (rq->fence.context == last_context &&
+ rq->fence.seqno < last_seqno)) {
+ pr_err("[%lu] %llx:%lld [prio:%d] after
%llx:%lld [prio:%d]\n",
+ count,
+ rq->fence.context,
+ rq->fence.seqno,
+ rq_prio(rq),
+ last_context,
+ last_seqno,
+ last_prio);
+ goto out_unlock;
+ }
+
+ last_context = rq->fence.context;
+ last_seqno = rq->fence.seqno;
+ last_prio = rq_prio(rq);
+ count++;
+ }
+ }
+ result = true;
+out_unlock:
+ spin_unlock_irq(&engine->active.lock);
+
+ return result;
+}
+
+static int __single_chain(struct intel_engine_cs *engine, unsigned long length,
+ void (*fn)(struct i915_request *rq,
+ unsigned long v, unsigned long e))
+{
+ struct intel_context *ce;
+ struct igt_spinner spin;
+ struct i915_request *rq;
+ unsigned long count;
+ unsigned long min;
+ int err = 0;
+
+ scheduling_disable(engine);
+
+ if (igt_spinner_init(&spin, engine->gt)) {
+ err = -ENOMEM;
+ goto err_heartbeat;
+ }
+
+ ce = intel_context_create(engine);
+ if (IS_ERR(ce)) {
+ err = PTR_ERR(ce);
+ goto err_spin;
+ }
+ ce->ring = __intel_context_ring_size(SZ_512K);
+
+ rq = igt_spinner_create_request(&spin, ce, MI_NOOP);
+ if (IS_ERR(rq)) {
+ err = PTR_ERR(rq);
+ goto err_context;
+ }
+ i915_request_add(rq);
+ min = ce->ring->size - ce->ring->space;
+
+ count = 1;
+ while (count < length && ce->ring->space > min) {
+ rq = intel_context_create_request(ce);
+ if (IS_ERR(rq)) {
+ err = PTR_ERR(rq);
+ break;
+ }
+ i915_request_add(rq);
+ count++;
+ }
+
+ tasklet_disable(&engine->execlists.tasklet);
+ local_bh_disable();
+ fn(rq, count, count - 1);
+ if (!check_context_order(engine))
+ err = -EINVAL;
+ local_bh_enable();
+ tasklet_enable(&engine->execlists.tasklet);
+
+ igt_spinner_end(&spin);
+err_context:
+ intel_context_put(ce);
+err_spin:
+ igt_spinner_fini(&spin);
+err_heartbeat:
+ scheduling_enable(engine);
+ return err;
+}
+
+static int __wide_chain(struct intel_engine_cs *engine, unsigned long width,
+ void (*fn)(struct i915_request *rq,
+ unsigned long v, unsigned long e))
+{
+ struct intel_context **ce;
+ struct i915_request **rq;
+ struct igt_spinner spin;
+ unsigned long count;
+ unsigned long i, j;
+ int err = 0;
+
+ scheduling_disable(engine);
+
+ if (igt_spinner_init(&spin, engine->gt)) {
+ err = -ENOMEM;
+ goto err_heartbeat;
+ }
+
+ ce = kmalloc_array(width, sizeof(*ce), GFP_KERNEL);
+ if (!ce) {
+ err = -ENOMEM;
+ goto err_spin;
+ }
+
+ for (i = 0; i < width; i++) {
+ ce[i] = intel_context_create(engine);
+ if (IS_ERR(ce[i])) {
+ err = PTR_ERR(ce[i]);
+ width = i;
+ goto err_context;
+ }
+ }
+
+ rq = kmalloc_array(width, sizeof(*rq), GFP_KERNEL);
+ if (!rq) {
+ err = -ENOMEM;
+ goto err_context;
+ }
+
+ rq[0] = igt_spinner_create_request(&spin, ce[0], MI_NOOP);
+ if (IS_ERR(rq[0])) {
+ err = PTR_ERR(rq[0]);
+ goto err_free;
+ }
+ i915_request_add(rq[0]);
+
+ count = 0;
+ for (i = 1; i < width; i++) {
+ GEM_BUG_ON(i915_request_completed(rq[0]));
+
+ rq[i] = intel_context_create_request(ce[i]);
+ if (IS_ERR(rq[i])) {
+ err = PTR_ERR(rq[i]);
+ break;
+ }
+ for (j = 0; j < i; j++) {
+ err = i915_request_await_dma_fence(rq[i],
+ &rq[j]->fence);
+ if (err)
+ break;
+ count++;
+ }
+ i915_request_add(rq[i]);
+ }
+
+ tasklet_disable(&engine->execlists.tasklet);
+ local_bh_disable();
+ fn(rq[i - 1], i, count);
+ if (!check_context_order(engine))
+ err = -EINVAL;
+ local_bh_enable();
+ tasklet_enable(&engine->execlists.tasklet);
+
+ igt_spinner_end(&spin);
+err_free:
+ kfree(rq);
+err_context:
+ for (i = 0; i < width; i++)
+ intel_context_put(ce[i]);
+ kfree(ce);
+err_spin:
+ igt_spinner_fini(&spin);
+err_heartbeat:
+ scheduling_enable(engine);
+ return err;
+}
+
+static int __inv_chain(struct intel_engine_cs *engine, unsigned long width,
+ void (*fn)(struct i915_request *rq,
+ unsigned long v, unsigned long e))
+{
+ struct intel_context **ce;
+ struct i915_request **rq;
+ struct igt_spinner spin;
+ unsigned long count;
+ unsigned long i, j;
+ int err = 0;
+
+ scheduling_disable(engine);
+
+ if (igt_spinner_init(&spin, engine->gt)) {
+ err = -ENOMEM;
+ goto err_heartbeat;
+ }
+
+ ce = kmalloc_array(width, sizeof(*ce), GFP_KERNEL);
+ if (!ce) {
+ err = -ENOMEM;
+ goto err_spin;
+ }
+
+ for (i = 0; i < width; i++) {
+ ce[i] = intel_context_create(engine);
+ if (IS_ERR(ce[i])) {
+ err = PTR_ERR(ce[i]);
+ width = i;
+ goto err_context;
+ }
+ }
+
+ rq = kmalloc_array(width, sizeof(*rq), GFP_KERNEL);
+ if (!rq) {
+ err = -ENOMEM;
+ goto err_context;
+ }
+
+ rq[0] = igt_spinner_create_request(&spin, ce[0], MI_NOOP);
+ if (IS_ERR(rq[0])) {
+ err = PTR_ERR(rq[0]);
+ goto err_free;
+ }
+ i915_request_add(rq[0]);
+
+ count = 0;
+ for (i = 1; i < width; i++) {
+ GEM_BUG_ON(i915_request_completed(rq[0]));
+
+ rq[i] = intel_context_create_request(ce[i]);
+ if (IS_ERR(rq[i])) {
+ err = PTR_ERR(rq[i]);
+ break;
+ }
+ for (j = i; j > 0; j--) {
+ err = i915_request_await_dma_fence(rq[i],
+ &rq[j - 1]->fence);
+ if (err)
+ break;
+ count++;
+ }
+ i915_request_add(rq[i]);
+ }
+
+ tasklet_disable(&engine->execlists.tasklet);
+ local_bh_disable();
+ fn(rq[i - 1], i, count);
+ if (!check_context_order(engine))
+ err = -EINVAL;
+ local_bh_enable();
+ tasklet_enable(&engine->execlists.tasklet);
+
+ igt_spinner_end(&spin);
+err_free:
+ kfree(rq);
+err_context:
+ for (i = 0; i < width; i++)
+ intel_context_put(ce[i]);
+ kfree(ce);
+err_spin:
+ igt_spinner_fini(&spin);
+err_heartbeat:
+ scheduling_enable(engine);
+ return err;
+}
+
+static int igt_single(struct drm_i915_private *i915,
+ void (*fn)(struct i915_request *rq,
+ unsigned long v, unsigned long e))
+{
+ return all_engines(i915, __single_chain, 17, fn);
+}
+
+static int igt_wide(struct drm_i915_private *i915,
+ void (*fn)(struct i915_request *rq,
+ unsigned long v, unsigned long e))
+{
+ return all_engines(i915, __wide_chain, 17, fn);
+}
+
+static int igt_inv(struct drm_i915_private *i915,
+ void (*fn)(struct i915_request *rq,
+ unsigned long v, unsigned long e))
+{
+ return all_engines(i915, __inv_chain, 17, fn);
+}
+
+static void igt_priority(struct i915_request *rq,
+ unsigned long v, unsigned long e)
+{
+ i915_request_set_priority(rq, I915_PRIORITY_BARRIER);
+ GEM_BUG_ON(rq_prio(rq) != I915_PRIORITY_BARRIER);
+}
+
+static int igt_priority_single(void *arg)
+{
+ return igt_single(arg, igt_priority);
+}
+
+static int igt_priority_wide(void *arg)
+{
+ return igt_wide(arg, igt_priority);
+}
+
+static int igt_priority_inv(void *arg)
+{
+ return igt_inv(arg, igt_priority);
+}
+
+int i915_scheduler_live_selftests(struct drm_i915_private *i915)
+{
+ static const struct i915_subtest tests[] = {
+ SUBTEST(igt_priority_single),
+ SUBTEST(igt_priority_wide),
+ SUBTEST(igt_priority_inv),
+ };
+
+ return i915_subtests(tests, i915);
+}
+
+static int chains(struct drm_i915_private *i915,
+ int (*chain)(struct drm_i915_private *i915,
+ unsigned long length,
+ void (*fn)(struct i915_request *rq,
+ unsigned long v, unsigned long e)),
+ void (*fn)(struct i915_request *rq,
+ unsigned long v, unsigned long e))
+{
+ unsigned long x[] = { 1, 4, 16, 64, 128, 256, 512, 1024, 4096 };
+ int i, err;
+
+ for (i = 0; i < ARRAY_SIZE(x); i++) {
+ IGT_TIMEOUT(end_time);
+
+ err = chain(i915, x[i], fn);
+ if (err)
+ return err;
+
+ if (__igt_timeout(end_time, NULL))
+ break;
+ }
+
+ return 0;
+}
+
+static int single_chain(struct drm_i915_private *i915,
+ unsigned long length,
+ void (*fn)(struct i915_request *rq,
+ unsigned long v, unsigned long e))
+{
+ return first_engine(i915, __single_chain, length, fn);
+}
+
+static int single(struct drm_i915_private *i915,
+ void (*fn)(struct i915_request *rq,
+ unsigned long v, unsigned long e))
+{
+ return chains(i915, single_chain, fn);
+}
+
+static int wide_chain(struct drm_i915_private *i915,
+ unsigned long width,
+ void (*fn)(struct i915_request *rq,
+ unsigned long v, unsigned long e))
+{
+ return first_engine(i915, __wide_chain, width, fn);
+}
+
+static int wide(struct drm_i915_private *i915,
+ void (*fn)(struct i915_request *rq,
+ unsigned long v, unsigned long e))
+{
+ return chains(i915, wide_chain, fn);
+}
+
+static int inv_chain(struct drm_i915_private *i915,
+ unsigned long width,
+ void (*fn)(struct i915_request *rq,
+ unsigned long v, unsigned long e))
+{
+ return first_engine(i915, __inv_chain, width, fn);
+}
+
+static int inv(struct drm_i915_private *i915,
+ void (*fn)(struct i915_request *rq,
+ unsigned long v, unsigned long e))
+{
+ return chains(i915, inv_chain, fn);
+}
+
+static void report(const char *what, unsigned long v, unsigned long e, u64 dt)
+{
+ pr_info("(%4lu, %7lu), %s:%10lluns\n", v, e, what, dt);
+}
+
+static u64 __set_priority(struct i915_request *rq, int prio)
+{
+ u64 dt;
+
+ preempt_disable();
+ dt = ktime_get_raw_fast_ns();
+ i915_request_set_priority(rq, prio);
+ dt = ktime_get_raw_fast_ns() - dt;
+ preempt_enable();
+
+ return dt;
+}
+
+static void set_priority(struct i915_request *rq,
+ unsigned long v, unsigned long e)
+{
+ report("set-priority", v, e, __set_priority(rq, I915_PRIORITY_BARRIER));
+}
+
+static int single_priority(void *arg)
+{
+ return single(arg, set_priority);
+}
+
+static int wide_priority(void *arg)
+{
+ return wide(arg, set_priority);
+}
+
+static int inv_priority(void *arg)
+{
+ return inv(arg, set_priority);
+}
+
+int i915_scheduler_perf_selftests(struct drm_i915_private *i915)
+{
+ static const struct i915_subtest tests[] = {
+ SUBTEST(single_priority),
+ SUBTEST(wide_priority),
+ SUBTEST(inv_priority),
+ };
+
+ return i915_subtests(tests, i915);
+}
--
2.20.1
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