[SYCL] Exit early while trying to enqueue blocked tasks (#2347)

Author: DenisBakhvalov

sycl/source/detail/scheduler/commands.hpp

@@ -122,14 +122,18 @@ class Command {
   /// \param Blocking if this argument is true, function will wait for the
   ///        command to be unblocked before calling enqueueImp.
   /// \return true if the command is enqueued.
-  bool enqueue(EnqueueResultT &EnqueueResult, BlockingT Blocking);
+  virtual bool enqueue(EnqueueResultT &EnqueueResult, BlockingT Blocking);
 
   bool isFinished();
 
   bool isSuccessfullyEnqueued() const {
     return MEnqueueStatus == EnqueueResultT::SyclEnqueueSuccess;
   }
 
+  bool isEnqueueBlocked() const {
+    return MEnqueueStatus == EnqueueResultT::SyclEnqueueBlocked;
+  }
+
   std::shared_ptr<queue_impl> getQueue() const { return MQueue; }
 
   std::shared_ptr<event_impl> getEvent() const { return MEvent; }

sycl/source/detail/scheduler/graph_processor.cpp

@@ -58,33 +58,19 @@ bool Scheduler::GraphProcessor::enqueueCommand(Command *Cmd,
   if (!Cmd || Cmd->isSuccessfullyEnqueued())
     return true;
 
-  // Indicates whether dependency cannot be enqueued
-  bool BlockedByDep = false;
+  // Exit early if the command is blocked and the enqueue type is non-blocking
+  if (Cmd->isEnqueueBlocked() && !Blocking) {
+    EnqueueResult = EnqueueResultT(EnqueueResultT::SyclEnqueueBlocked, Cmd);
+    return false;
+  }
 
+  // Recursively enqueue all the dependencies first and
+  // exit immediately if any of the commands cannot be enqueued.
   for (DepDesc &Dep : Cmd->MDeps) {
-    const bool Enqueued =
-        enqueueCommand(Dep.MDepCommand, EnqueueResult, Blocking);
-    if (!Enqueued)
-      switch (EnqueueResult.MResult) {
-      case EnqueueResultT::SyclEnqueueFailed:
-      default:
-        // Exit immediately if a command fails to avoid enqueueing commands
-        // result of which will be discarded.
-        return false;
-      case EnqueueResultT::SyclEnqueueBlocked:
-        // If some dependency is blocked from enqueueing remember that, but
-        // try to enqueue other dependencies(that can be ready for
-        // enqueueing).
-        BlockedByDep = true;
-        break;
-      }
+    if (!enqueueCommand(Dep.MDepCommand, EnqueueResult, Blocking))
+      return false;
   }
 
-  // Exit if some command is blocked from enqueueing, the EnqueueResult is set
-  // by the latest dependency which was blocked.
-  if (BlockedByDep)
-    return false;
-
   return Cmd->enqueue(EnqueueResult, Blocking);
 }
 

sycl/unittests/scheduler/BlockedCommands.cpp

@@ -10,6 +10,7 @@
 #include "SchedulerTestUtils.hpp"
 
 using namespace cl::sycl;
+using namespace testing;
 
 TEST_F(SchedulerTest, BlockedCommands) {
   MockCommand MockCmd(detail::getSyclObjImpl(MQueue));
@@ -45,3 +46,87 @@ TEST_F(SchedulerTest, BlockedCommands) {
               Res.MResult == detail::EnqueueResultT::SyclEnqueueSuccess)
       << "The command is expected to be successfully enqueued.\n";
 }
+
+TEST_F(SchedulerTest, DontEnqueueDepsIfOneOfThemIsBlocked) {
+  MockCommand A(detail::getSyclObjImpl(MQueue));
+  A.MEnqueueStatus = detail::EnqueueResultT::SyclEnqueueReady;
+  A.MIsBlockable = true;
+  A.MRetVal = CL_SUCCESS;
+
+  MockCommand B(detail::getSyclObjImpl(MQueue));
+  B.MEnqueueStatus = detail::EnqueueResultT::SyclEnqueueReady;
+  B.MIsBlockable = true;
+  B.MRetVal = CL_SUCCESS;
+
+  MockCommand C(detail::getSyclObjImpl(MQueue));
+  C.MEnqueueStatus = detail::EnqueueResultT::SyclEnqueueBlocked;
+  C.MIsBlockable = true;
+
+  MockCommand D(detail::getSyclObjImpl(MQueue));
+  D.MEnqueueStatus = detail::EnqueueResultT::SyclEnqueueReady;
+  D.MIsBlockable = true;
+  D.MRetVal = CL_SUCCESS;
+
+  addEdge(&A, &B, nullptr);
+  addEdge(&A, &C, nullptr);
+  addEdge(&A, &D, nullptr);
+
+  // We have such a graph:
+  //
+  //     A
+  //   / | \
+  //  B  C  D
+  //
+  // If C is blocked, we should not try to enqueue D.
+
+  EXPECT_CALL(A, enqueue(_, _)).Times(0);
+  EXPECT_CALL(B, enqueue(_, _)).Times(1);
+  EXPECT_CALL(C, enqueue(_, _)).Times(0);
+  EXPECT_CALL(D, enqueue(_, _)).Times(0);
+
+  detail::EnqueueResultT Res;
+  bool Enqueued = MockScheduler::enqueueCommand(&A, Res, detail::NON_BLOCKING);
+  ASSERT_FALSE(Enqueued) << "Blocked command should not be enqueued\n";
+  ASSERT_EQ(detail::EnqueueResultT::SyclEnqueueBlocked, Res.MResult)
+      << "Result of enqueueing blocked command should be BLOCKED.\n";
+  ASSERT_EQ(&C, Res.MCmd) << "Expected different failed command.\n";
+}
+
+TEST_F(SchedulerTest, EnqueueBlockedCommandEarlyExit) {
+  MockCommand A(detail::getSyclObjImpl(MQueue));
+  A.MEnqueueStatus = detail::EnqueueResultT::SyclEnqueueBlocked;
+  A.MIsBlockable = true;
+
+  MockCommand B(detail::getSyclObjImpl(MQueue));
+  B.MEnqueueStatus = detail::EnqueueResultT::SyclEnqueueReady;
+  B.MRetVal = CL_OUT_OF_RESOURCES;
+
+  addEdge(&A, &B, nullptr);
+
+  // We have such a graph:
+  //
+  //   A -> B
+  //
+  // If A is blocked, we should not try to enqueue B.
+
+  EXPECT_CALL(A, enqueue(_, _)).Times(0);
+  EXPECT_CALL(B, enqueue(_, _)).Times(0);
+
+  detail::EnqueueResultT Res;
+  bool Enqueued = MockScheduler::enqueueCommand(&A, Res, detail::NON_BLOCKING);
+  ASSERT_FALSE(Enqueued) << "Blocked command should not be enqueued\n";
+  ASSERT_EQ(detail::EnqueueResultT::SyclEnqueueBlocked, Res.MResult)
+      << "Result of enqueueing blocked command should be BLOCKED.\n";
+  ASSERT_EQ(&A, Res.MCmd) << "Expected different failed command.\n";
+
+  // But if the enqueue type is blocking we should not exit early.
+
+  EXPECT_CALL(A, enqueue(_, _)).Times(0);
+  EXPECT_CALL(B, enqueue(_, _)).Times(1);
+
+  Enqueued = MockScheduler::enqueueCommand(&A, Res, detail::BLOCKING);
+  ASSERT_FALSE(Enqueued) << "Blocked command should not be enqueued\n";
+  ASSERT_EQ(detail::EnqueueResultT::SyclEnqueueFailed, Res.MResult)
+      << "Result of enqueueing blocked command should be BLOCKED.\n";
+  ASSERT_EQ(&B, Res.MCmd) << "Expected different failed command.\n";
+}

sycl/unittests/scheduler/LeafLimit.cpp

@@ -21,42 +21,45 @@ using namespace cl::sycl;
 // overflowed.
 TEST_F(SchedulerTest, LeafLimit) {
   MockScheduler MS;
+  std::vector<std::unique_ptr<MockCommand>> LeavesToAdd;
+  std::unique_ptr<MockCommand> MockDepCmd;
 
   buffer<int, 1> Buf(range<1>(1));
   detail::Requirement MockReq = getMockRequirement(Buf);
-  MockCommand *MockDepCmd =
-      new MockCommand(detail::getSyclObjImpl(MQueue), MockReq);
+
+  MockDepCmd =
+      std::make_unique<MockCommand>(detail::getSyclObjImpl(MQueue), MockReq);
   detail::MemObjRecord *Rec =
       MS.getOrInsertMemObjRecord(detail::getSyclObjImpl(MQueue), &MockReq);
 
   // Create commands that will be added as leaves exceeding the limit by 1
-  std::vector<MockCommand *> LeavesToAdd;
   for (std::size_t i = 0; i < Rec->MWriteLeaves.genericCommandsCapacity() + 1;
        ++i) {
     LeavesToAdd.push_back(
-        new MockCommand(detail::getSyclObjImpl(MQueue), MockReq));
+        std::make_unique<MockCommand>(detail::getSyclObjImpl(MQueue), MockReq));
   }
   // Create edges: all soon-to-be leaves are direct users of MockDep
-  for (auto Leaf : LeavesToAdd) {
-    MockDepCmd->addUser(Leaf);
-    Leaf->addDep(detail::DepDesc{MockDepCmd, Leaf->getRequirement(), nullptr});
+  for (auto &Leaf : LeavesToAdd) {
+    MockDepCmd->addUser(Leaf.get());
+    Leaf->addDep(
+        detail::DepDesc{MockDepCmd.get(), Leaf->getRequirement(), nullptr});
   }
   // Add edges as leaves and exceed the leaf limit
-  for (auto LeafPtr : LeavesToAdd) {
-    MS.addNodeToLeaves(Rec, LeafPtr);
+  for (auto &LeafPtr : LeavesToAdd) {
+    MS.addNodeToLeaves(Rec, LeafPtr.get());
   }
   // Check that the oldest leaf has been removed from the leaf list
   // and added as a dependency of the newest one instead
   const detail::CircularBuffer<detail::Command *> &Leaves =
       Rec->MWriteLeaves.getGenericCommands();
-  ASSERT_TRUE(std::find(Leaves.begin(), Leaves.end(), LeavesToAdd.front()) ==
-              Leaves.end());
+  ASSERT_TRUE(std::find(Leaves.begin(), Leaves.end(),
+                        LeavesToAdd.front().get()) == Leaves.end());
   for (std::size_t i = 1; i < LeavesToAdd.size(); ++i) {
-    assert(std::find(Leaves.begin(), Leaves.end(), LeavesToAdd[i]) !=
+    assert(std::find(Leaves.begin(), Leaves.end(), LeavesToAdd[i].get()) !=
            Leaves.end());
   }
-  MockCommand *OldestLeaf = LeavesToAdd.front();
-  MockCommand *NewestLeaf = LeavesToAdd.back();
+  MockCommand *OldestLeaf = LeavesToAdd.front().get();
+  MockCommand *NewestLeaf = LeavesToAdd.back().get();
   ASSERT_EQ(OldestLeaf->MUsers.size(), 1U);
   EXPECT_GT(OldestLeaf->MUsers.count(NewestLeaf), 0U);
   ASSERT_EQ(NewestLeaf->MDeps.size(), 2U);

sycl/unittests/scheduler/SchedulerTestUtils.hpp

@@ -13,6 +13,8 @@
 #include <detail/scheduler/scheduler.hpp>
 
 #include <functional>
+#include <gmock/gmock.h>
+
 // This header contains a few common classes/methods used in
 // execution graph testing.
 
@@ -24,12 +26,22 @@ class MockCommand : public cl::sycl::detail::Command {
               cl::sycl::detail::Requirement Req,
               cl::sycl::detail::Command::CommandType Type =
                   cl::sycl::detail::Command::RUN_CG)
-      : Command{Type, Queue}, MRequirement{std::move(Req)} {}
+      : Command{Type, Queue}, MRequirement{std::move(Req)} {
+    using namespace testing;
+    ON_CALL(*this, enqueue(_, _))
+        .WillByDefault(Invoke(this, &MockCommand::enqueueOrigin));
+    EXPECT_CALL(*this, enqueue(_, _)).Times(AnyNumber());
+  }
 
   MockCommand(cl::sycl::detail::QueueImplPtr Queue,
               cl::sycl::detail::Command::CommandType Type =
                   cl::sycl::detail::Command::RUN_CG)
-      : Command{Type, Queue}, MRequirement{std::move(getMockRequirement())} {}
+      : Command{Type, Queue}, MRequirement{std::move(getMockRequirement())} {
+    using namespace testing;
+    ON_CALL(*this, enqueue(_, _))
+        .WillByDefault(Invoke(this, &MockCommand::enqueueOrigin));
+    EXPECT_CALL(*this, enqueue(_, _)).Times(AnyNumber());
+  }
 
   void printDot(std::ostream &) const override {}
   void emitInstrumentationData() override {}
@@ -40,6 +52,13 @@ class MockCommand : public cl::sycl::detail::Command {
 
   cl_int enqueueImp() override { return MRetVal; }
 
+  MOCK_METHOD2(enqueue, bool(cl::sycl::detail::EnqueueResultT &,
+                             cl::sycl::detail::BlockingT));
+  bool enqueueOrigin(cl::sycl::detail::EnqueueResultT &EnqueueResult,
+                     cl::sycl::detail::BlockingT Blocking) {
+    return cl::sycl::detail::Command::enqueue(EnqueueResult, Blocking);
+  }
+
   cl_int MRetVal = CL_SUCCESS;
 
   void waitForEventsCall(