Added a test for multithreaded full reductions

2 files changed, 32 insertions, 0 deletions

diff --git a/unsupported/Eigen/CXX11/src/Tensor/TensorFunctors.h b/unsupported/Eigen/CXX11/src/Tensor/TensorFunctors.h
index 1b031b7a1..33e8c01c2 100644
--- a/unsupported/Eigen/CXX11/src/Tensor/TensorFunctors.h
+++ b/unsupported/Eigen/CXX11/src/Tensor/TensorFunctors.h
@@ -17,6 +17,7 @@ namespace internal {
 template <typename T> struct SumReducer
 {
   static const bool PacketAccess = true;
+  static const bool IsStateful = false;
 
   EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE void reduce(const T t, T* accum) const {
     (*accum) += t;
@@ -49,6 +50,8 @@ template <typename T> struct SumReducer
 template <typename T> struct MeanReducer
 {
   static const bool PacketAccess = true;
+  static const bool IsStateful = true;
+
   MeanReducer() : scalarCount_(0), packetCount_(0) { }
 
   EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE void reduce(const T t, T* accum) {
@@ -88,6 +91,7 @@ template <typename T> struct MeanReducer
 template <typename T> struct MaxReducer
 {
   static const bool PacketAccess = true;
+  static const bool IsStateful = false;
 
   EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE void reduce(const T t, T* accum) const {
     if (t > *accum) { *accum = t; }
@@ -120,6 +124,7 @@ template <typename T> struct MaxReducer
 template <typename T> struct MinReducer
 {
   static const bool PacketAccess = true;
+  static const bool IsStateful = false;
 
   EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE void reduce(const T t, T* accum) const {
     if (t < *accum) { *accum = t; }
@@ -153,6 +158,7 @@ template <typename T> struct MinReducer
 template <typename T> struct ProdReducer
 {
   static const bool PacketAccess = true;
+  static const bool IsStateful = false;
 
   EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE void reduce(const T t, T* accum) const {
     (*accum) *= t;
diff --git a/unsupported/test/cxx11_tensor_thread_pool.cpp b/unsupported/test/cxx11_tensor_thread_pool.cpp
index 0a20a01a4..5ec7c8bf4 100644
--- a/unsupported/test/cxx11_tensor_thread_pool.cpp
+++ b/unsupported/test/cxx11_tensor_thread_pool.cpp
@@ -228,6 +228,29 @@ static void test_multithread_contraction_agrees_with_singlethread() {
 }
 
 
+template<int DataLayout>
+static void test_multithreaded_reductions() {
+  const int num_threads = internal::random<int>(3, 11);
+  ThreadPool thread_pool(num_threads);
+  Eigen::ThreadPoolDevice thread_pool_device(&thread_pool, num_threads);
+
+  const int num_rows = internal::random<int>(13, 732);
+  const int num_cols = internal::random<int>(13, 732);
+  Tensor<float, 2, DataLayout> t1(num_rows, num_cols);
+  t1.setRandom();
+
+  Tensor<float, 1, DataLayout> full_redux(1);
+  full_redux = t1.sum();
+
+  Tensor<float, 1, DataLayout> full_redux_tp(1);
+  full_redux_tp.device(thread_pool_device) = t1.sum();
+
+  // Check that the single threaded and the multi threaded reductions return
+  // the same result.
+  VERIFY_IS_APPROX(full_redux(0), full_redux_tp(0));
+}
+
+
 static void test_memcpy() {
 
   for (int i = 0; i < 5; ++i) {
@@ -271,6 +294,9 @@ void test_cxx11_tensor_thread_pool()
   CALL_SUBTEST(test_contraction_corner_cases<ColMajor>());
   CALL_SUBTEST(test_contraction_corner_cases<RowMajor>());
 
+  CALL_SUBTEST(test_multithreaded_reductions<ColMajor>());
+  CALL_SUBTEST(test_multithreaded_reductions<RowMajor>());
+
   CALL_SUBTEST(test_memcpy());
 
   CALL_SUBTEST(test_multithread_random());