EXPERIMENTAL, Trying Ross's suggestion

content/renderer/scheduler/task_queue_manager_perftest.cc

Index: content/renderer/scheduler/task_queue_manager_perftest.cc
diff --git a/content/renderer/scheduler/task_queue_manager_perftest.cc b/content/renderer/scheduler/task_queue_manager_perftest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..9af5476c2e850a262282c4477630811bb5c90097
--- /dev/null
+++ b/content/renderer/scheduler/task_queue_manager_perftest.cc
@@ -0,0 +1,142 @@
+
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "content/renderer/scheduler/task_queue_manager.h"
+
+#include <functional>
+#include "base/bind.h"
+#include "base/threading/thread.h"
+#include "content/renderer/scheduler/task_queue_selector.h"
+#include "testing/gmock/include/gmock/gmock.h"
+#include "testing/perf/perf_test.h"
+
+namespace content {
+
+namespace {
+
+class SelectorForTest : public TaskQueueSelector {
+ public:
+  SelectorForTest() {}
+
+  void RegisterWorkQueues(
+      const std::vector<const base::TaskQueue*>& work_queues) override {
+    work_queues_ = work_queues;
+  }
+
+  bool SelectWorkQueueToService(size_t* out_queue_index) override {
+    // Choose the oldest task, if any.
+    bool found_one = false;
+    for (size_t i = 0; i < work_queues_.size(); i++) {
+      if (work_queues_[i]->empty())
+        continue;
+      // Note: the < comparison is correct due to the fact that the PendingTask
+      // operator inverts its comparison operation in order to work well in a
+      // heap based priority queue.
+      if (!found_one ||
+          work_queues_[*out_queue_index]->front() < work_queues_[i]->front())
+        *out_queue_index = i;
+      found_one = true;
+    }
+    return found_one;
+  }
+
+  void AsValueInto(base::trace_event::TracedValue* state) const override {}
+
+ private:
+  std::vector<const base::TaskQueue*> work_queues_;
+
+  DISALLOW_COPY_AND_ASSIGN(SelectorForTest);
+};
+
+}  // namespace
+
+class TaskQueueManagerPerfTest : public testing::Test {
+ protected:
+  void Initialize(size_t num_queues) {
+    num_queues_ = num_queues;
+    message_loop_.reset(new base::MessageLoop());
+    selector_ = make_scoped_ptr(new SelectorForTest);
+    manager_ = make_scoped_ptr(new TaskQueueManager(
+        num_queues, message_loop_->task_runner(), selector_.get()));
+  }
+
+  void Benchmark(const std::string& trace, std::function<void()> fn) {
+    base::TimeTicks start = base::TimeTicks::Now();
+    base::TimeTicks now;
+    unsigned long long num_iterations = 0;
+    do {
+      fn();
+      now = base::TimeTicks::Now();
+      num_iterations++;
+    } while (now - start < base::TimeDelta::FromSeconds(5));
+    perf_test::PrintResult(
+        "task", "", trace,
+        (now - start).InMicroseconds() / static_cast<double>(num_iterations),
+        "us/run", true);
+  }
+
+  void TestTask() {
+    // Post a variable number of tasks.
+    unsigned int num_posts = 1 + sequence_number_ % 8;
+    for (unsigned int i = 0; i < num_posts; i++) {
+      if (++sequence_number_ < 10000) {
+        // Choose a queue weighted towards queue 0.
+        unsigned int queue = sequence_number_ % (num_queues_ + 1);
+        if (queue == num_queues_) {
+          queue = 0;
+        }
+        base::TimeDelta delay(
+            base::TimeDelta::FromMilliseconds(sequence_number_ % 10));
+        scoped_refptr<base::SingleThreadTaskRunner> runner =
+            manager_->TaskRunnerForQueue(queue);
+        runner->PostDelayedTask(FROM_HERE,
+                                base::Bind(&TaskQueueManagerPerfTest::TestTask,
+                                           base::Unretained(this)),
+                                delay);
+      } else {
+        message_loop_->Quit();
+        return;
+      }
+    }
+  }
+
+  size_t num_queues_;
+  unsigned int sequence_number_;
+  scoped_ptr<SelectorForTest> selector_;
+  scoped_ptr<TaskQueueManager> manager_;
+  scoped_ptr<base::MessageLoop> message_loop_;
+};
+
+TEST_F(TaskQueueManagerPerfTest, RunTenThousandDelayedTasks_OneQueue) {
+  Initialize(1u);
+
+  Benchmark("post 10000 delayed tasks", [this]() {
+    sequence_number_ = 0;
+    TestTask();
+    message_loop_->Run();
+  });
+}
+
+TEST_F(TaskQueueManagerPerfTest, RunTenThousandDelayedTasks_FourQueues) {
+  Initialize(4u);
+
+  Benchmark("post 10000 delayed tasks", [this]() {
+    sequence_number_ = 0;
+    TestTask();
+    message_loop_->Run();
+  });
+}
+
+TEST_F(TaskQueueManagerPerfTest, RunTenThousandDelayedTasks_EightQueues) {
+  Initialize(8u);
+
+  Benchmark("post 10000 delayed tasks", [this]() {
+    sequence_number_ = 0;
+    TestTask();
+    message_loop_->Run();
+  });
+}
+
+}  // namespace content