GpuScheduler no longer spins when it is waiting on a latch.

BUG=79632
TEST=run trace in about:gpu; observe the number of times the GPU process sequentially calls WaitLatch; verify it is not spinning.

Review URL: http://codereview.chromium.org/6874029

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@82033 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 28 insertions, 0 deletions

diff --git a/content/common/gpu/gpu_channel.cc b/content/common/gpu/gpu_channel.cc
index 21b6d06..0da5925 100644
--- a/content/common/gpu/gpu_channel.cc
+++ b/content/common/gpu/gpu_channel.cc
@@ -55,6 +55,25 @@ void GpuChannel::DestroyTransportTexture(int32 route_id) {
   router_.RemoveRoute(route_id);
 }
 
+void GpuChannel::OnLatchCallback(int route_id, bool is_set_latch) {
+#if defined(ENABLE_GPU)
+  if (is_set_latch) {
+    // Wake up any waiting contexts. If they are still blocked, they will re-add
+    // themselves to the set.
+    for (std::set<int32>::iterator i = latched_routes_.begin();
+         i != latched_routes_.end(); ++i) {
+      GpuCommandBufferStub* stub = stubs_.Lookup(*i);
+      if (stub)
+        stub->scheduler()->ScheduleProcessCommands();
+    }
+    latched_routes_.clear();
+  } else {
+    // Add route_id context to a set to be woken upon any set latch.
+    latched_routes_.insert(route_id);
+  }
+#endif
+}
+
 bool GpuChannel::OnMessageReceived(const IPC::Message& message) {
   if (log_messages_) {
     VLOG(1) << "received message @" << &message << " on channel @" << this
diff --git a/content/common/gpu/gpu_channel.h b/content/common/gpu/gpu_channel.h
index 012656e..05af1ca 100644
--- a/content/common/gpu/gpu_channel.h
+++ b/content/common/gpu/gpu_channel.h
@@ -89,6 +89,11 @@ class GpuChannel : public IPC::Channel::Listener,
   // TransportTexture to delete and detach itself.
   void DestroyTransportTexture(int32 route_id);
 
+  // A callback which is called after a Set/WaitLatch command is processed.
+  // The bool parameter will be true for SetLatch, and false for a WaitLatch
+  // that is blocked. An unblocked WaitLatch will not trigger a callback.
+  void OnLatchCallback(int route_id, bool is_set_latch);
+
  private:
   bool OnControlMessageReceived(const IPC::Message& msg);
 
@@ -131,6 +136,7 @@ class GpuChannel : public IPC::Channel::Listener,
 #if defined(ENABLE_GPU)
   typedef IDMap<GpuCommandBufferStub, IDMapOwnPointer> StubMap;
   StubMap stubs_;
+  std::set<int32> latched_routes_;
 #endif  // defined (ENABLE_GPU)
 
   // A collection of transport textures created.
diff --git a/content/common/gpu/gpu_command_buffer_stub.cc b/content/common/gpu/gpu_command_buffer_stub.cc
index 94c8c6f..42e086d 100644
--- a/content/common/gpu/gpu_command_buffer_stub.cc
+++ b/content/common/gpu/gpu_command_buffer_stub.cc
@@ -4,6 +4,7 @@
 
 #if defined(ENABLE_GPU)
 
+#include "base/bind.h"
 #include "base/process_util.h"
 #include "base/shared_memory.h"
 #include "build/build_config.h"
@@ -258,6 +259,8 @@ void GpuCommandBufferStub::OnInitialize(
                       &gpu::GpuScheduler::ProcessCommands));
       scheduler_->SetSwapBuffersCallback(
           NewCallback(this, &GpuCommandBufferStub::OnSwapBuffers));
+      scheduler_->SetLatchCallback(
+          base::Bind(&GpuChannel::OnLatchCallback, channel_, route_id_));
       if (watchdog_)
         scheduler_->SetCommandProcessedCallback(
             NewCallback(this, &GpuCommandBufferStub::OnCommandProcessed));