WIP GPU scheduler + delayed activation / tile draw

gpu/ipc/service/gpu_scheduler.cc

Index: gpu/ipc/service/gpu_scheduler.cc
diff --git a/gpu/ipc/service/gpu_scheduler.cc b/gpu/ipc/service/gpu_scheduler.cc
new file mode 100644
index 0000000000000000000000000000000000000000..596a57d118917fdb3139cc39c3bf9c66612113d9
--- /dev/null
+++ b/gpu/ipc/service/gpu_scheduler.cc
@@ -0,0 +1,194 @@
+// Copyright (c) 2016 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 "gpu/ipc/service/gpu_scheduler.h"
+
+#include <algorithm>
+
+#include "base/callback.h"
+#include "base/memory/ptr_util.h"
+#include "base/timer/timer.h"
+#include "base/trace_event/trace_event.h"
+#include "base/trace_event/trace_event_argument.h"
+#include "gpu/command_buffer/service/command_executor.h"
+#include "gpu/ipc/service/gpu_command_stream.h"
+
+namespace gpu {
+
+namespace {
+
+const int64_t kMinTimeSliceUs = 4000;
+const int64_t kMaxTimeSliceUs = 12000;
+
+}  // anonymous namespace
+
+std::unique_ptr<GpuScheduler> GpuScheduler::Create(
+    scoped_refptr<base::SingleThreadTaskRunner> task_runner) {
+  GpuSchedulerSettings settings;
+  settings.min_time_slice = base::TimeDelta::FromMicroseconds(kMinTimeSliceUs);
+  settings.max_time_slice = base::TimeDelta::FromMicroseconds(kMaxTimeSliceUs);
+  return base::WrapUnique(new GpuScheduler(settings, std::move(task_runner)));
+}
+
+GpuScheduler::GpuScheduler(
+    const GpuSchedulerSettings& settings,
+    scoped_refptr<base::SingleThreadTaskRunner> task_runner)
+    : settings_(settings),
+      task_runner_(std::move(task_runner)),
+      weak_factory_(this) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+}
+
+GpuScheduler::~GpuScheduler() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+}
+
+base::TimeTicks GpuScheduler::Now() {
+  return base::TimeTicks::Now();
+}
+
+void GpuScheduler::AddStream(GpuCommandStream* stream,
+                             GpuStreamPriority priority) {
+  base::AutoLock lock(lock_);
+  DCHECK(thread_checker_.CalledOnValidThread());
+  StreamInfo stream_info;
+  stream_info.stream = stream;
+  stream_info.priority = priority;
+  stream_info.ready = false;
+  streams_.push_back(stream_info);
+}
+
+void GpuScheduler::RemoveStream(GpuCommandStream* stream) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+
+  auto it = FindStream(stream);
+  DCHECK(it != streams_.end());
+  streams_.erase(it);
+
+  auto work_queue_it = FindScheduledStream(stream);
+  if (work_queue_it != work_queue_.end()) {
+    work_queue_.erase(work_queue_it);
+    std::make_heap(work_queue_.begin(), work_queue_.end());
+  }
+}
+
+std::vector<GpuScheduler::ScheduledStream>::iterator
+GpuScheduler::FindScheduledStream(GpuCommandStream* stream) {
+  return std::find_if(work_queue_.begin(), work_queue_.end(),
+                      [&stream](const ScheduledStream& sched_stream) {
+                        return sched_stream.stream == stream;
+                      });
+}
+
+std::vector<GpuScheduler::StreamInfo>::iterator GpuScheduler::FindStream(
+    GpuCommandStream* stream) {
+  return std::find_if(streams_.begin(), streams_.end(),
+                      [&stream](const StreamInfo& stream_info) {
+                        return stream_info.stream == stream;
+                      });
+}
+
+void GpuScheduler::ScheduleStream(GpuCommandStream* stream) {
+  base::AutoLock lock(lock_);
+
+  auto it = FindStream(stream);
+  DCHECK(it != streams_.end());
+  it->ready = true;
+  if (it->priority == GpuStreamPriority::REAL_TIME &&
+      FindScheduledStream(stream) == work_queue_.end()) {
+    needs_rescheduling_ = true;
+  }
+
+  if (!running_) {
+    TRACE_EVENT_ASYNC_BEGIN0("gpu", "GpuScheduler::Running", this);
+    running_ = true;
+    task_runner_->PostTask(FROM_HERE, base::Bind(&GpuScheduler::RunNextStream,
+                                                 weak_factory_.GetWeakPtr()));
+  }
+}
+
+void GpuScheduler::DescheduleStream(GpuCommandStream* stream) {
+  base::AutoLock lock(lock_);
+
+  auto it = FindStream(stream);
+  DCHECK(it != streams_.end());
+  it->ready = false;
+
+  auto work_queue_it = FindScheduledStream(stream);
+  if (work_queue_it != work_queue_.end()) {
+    work_queue_.erase(work_queue_it);
+    std::make_heap(work_queue_.begin(), work_queue_.end());
+  }
+}
+
+bool GpuScheduler::ShouldYield() {
+  base::AutoLock lock(lock_);
+  base::TimeTicks now = Now();
+  // Don't run for less than a minimum time slice to minimize context switches.
+  if (now - running_stream_start_time_ < settings_.min_time_slice)
+    return false;
+
+  // If we need to reschedule, don't run streams for longer than minimum.
+  if (needs_rescheduling_)
+    return true;
+
+  // Don't run for too long to share the thread with other tasks.
+  if (now - running_stream_start_time_ >= settings_.max_time_slice)
+    return true;
+
+  return false;
+}
+
+void GpuScheduler::RunNextStream() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+
+  ScheduledStream sched_stream = GetNextStream();
+  if (sched_stream.stream) {
+    running_stream_start_time_ = Now();
+    TRACE_EVENT2("gpu", "GpuScheduler::RunNextStream", "priority",
+                 GpuStreamPriorityToString(sched_stream.priority), "start_time",
+                 running_stream_start_time_);
+    sched_stream.stream->Run();
+
+    task_runner_->PostTask(FROM_HERE, base::Bind(&GpuScheduler::RunNextStream,
+                                                 weak_factory_.GetWeakPtr()));
+  }
+}
+
+GpuScheduler::ScheduledStream GpuScheduler::GetNextStream() {
+  base::AutoLock lock(lock_);
+
+  if (work_queue_.empty()) {
+    BuildWorkQueue();
+    needs_rescheduling_ = false;
+  }
+
+  if (work_queue_.empty()) {
+    TRACE_EVENT_ASYNC_END0("gpu", "GpuScheduler::Running", this);
+    running_ = false;
+    return ScheduledStream();
+  }
+
+  ScheduledStream sched_stream = work_queue_.front();
+  std::pop_heap(work_queue_.begin(), work_queue_.end());
+  work_queue_.pop_back();
+
+  return sched_stream;
+}
+
+void GpuScheduler::BuildWorkQueue() {
+  TRACE_EVENT0("gpu", "GpuScheduler::BuildWorkQueue");
+  work_queue_.clear();
+  for (const StreamInfo& stream_info : streams_) {
+    if (stream_info.ready) {
+      ScheduledStream sched_stream;
+      sched_stream.stream = stream_info.stream;
+      sched_stream.priority = stream_info.priority;
+      work_queue_.push_back(sched_stream);
+    }
+  }
+  std::make_heap(work_queue_.begin(), work_queue_.end());
+}
+
+}  // namespace gpu