From fcde2b2725566a9cde0c8930d2e80e6a044d6784 Mon Sep 17 00:00:00 2001
From: Qiao Longfei <qiaolongfei@baidu.com>
Date: Mon, 17 Dec 2018 10:29:59 +0800
Subject: [PATCH] add ForRangeIn

---
 paddle/fluid/operators/optimizers/adam_op.h |  7 ++-
 paddle/fluid/platform/for_range.h           | 55 +++++++++++++++++++++
 2 files changed, 60 insertions(+), 2 deletions(-)

diff --git a/paddle/fluid/operators/optimizers/adam_op.h b/paddle/fluid/operators/optimizers/adam_op.h
index 5870557bb..e8b977e2d 100644
--- a/paddle/fluid/operators/optimizers/adam_op.h
+++ b/paddle/fluid/operators/optimizers/adam_op.h
@@ -359,14 +359,17 @@ class AdamOpKernel : public framework::OpKernel<T> {
           param_out.template mutable_data<T>(ctx.GetPlace()), rows, row_numel,
           grad_merge.rows().size(), lazy_mode);
       if (lazy_mode) {
+        std::vector<int64_t> id_vector;
         size_t row_count = grad_merge.rows().size();
         for (size_t row_index = 0; row_index < row_count; ++row_index) {
           for (size_t offset = 0; offset < row_numel; ++offset) {
             size_t i = rows[row_index] * row_numel + offset;
-            T g = grad_data[row_index * row_numel + offset];
-            functor.adam_update(i, g);
+            id_vector.push_back(i);
           }
         }
+        platform::ForRangeIn<DeviceContext> for_range_in(
+            static_cast<const DeviceContext&>(ctx.device_context()), id_vector);
+        for_range_in(functor);
       } else {
         platform::ForRange<DeviceContext> for_range(
             static_cast<const DeviceContext&>(ctx.device_context()),
diff --git a/paddle/fluid/platform/for_range.h b/paddle/fluid/platform/for_range.h
index c153e80fe..9fbaa3672 100644
--- a/paddle/fluid/platform/for_range.h
+++ b/paddle/fluid/platform/for_range.h
@@ -13,11 +13,38 @@ See the License for the specific language governing permissions and
 limitations under the License. */
 
 #pragma once
+
+#include <vector>
+
+#include "paddle/fluid/framework/mixed_vector.h"
 #include "paddle/fluid/platform/device_context.h"
 
 namespace paddle {
 namespace platform {
 
+template <typename DeviceContext>
+struct ForRangeIn {
+  ForRangeIn(const DeviceContext& dev_ctx, std::vector<int64_t> range);
+
+  template <typename Function>
+  void operator()(Function func) const;
+};
+
+template <>
+struct ForRangeIn<CPUDeviceContext> {
+  ForRangeIn(const CPUDeviceContext& dev_ctx, std::vector<int64_t> range)
+      : range_(range) {}
+
+  template <typename Function>
+  void operator()(Function func) const {
+    for (auto i : range_) {
+      func(i);
+    }
+  }
+
+  std::vector<int64_t> range_;
+};
+
 template <typename DeviceContext>
 struct ForRange {
   ForRange(const DeviceContext& dev_ctx, size_t limit);
@@ -79,6 +106,34 @@ struct ForRange<CUDADeviceContext> {
   int limit_;
 };
 
+template <typename T, typename Function>
+__global__ static void ForRangeInElemwiseOp(Function func, T* vector,
+                                            int vector_size) {
+  size_t idx = static_cast<size_t>(blockIdx.x * blockDim.x + threadIdx.x);
+  if (idx < vector_size) {
+    func(vector[idx]);
+  }
+}
+
+template <>
+struct ForRangeIn<CUDADeviceContext> {
+  ForRange(const CUDADeviceContext& dev_ctx, std::vector<int64_t> range)
+      : dev_ctx_(dev_ctx), range_(range) {}
+
+  template <typename Function>
+  inline void operator()(Function func) const {
+    constexpr int num_threads = 1024;
+    int block_size = range_.size() <= num_threads ? limit_ : num_threads;
+    int grid_size = (range_.size() + num_threads - 1) / num_threads;
+
+    ForRangeInElemwiseOp<<<grid_size, block_size, 0, dev_ctx_.stream()>>>(
+        func, range_.data(), range_.size());
+  }
+
+  const CUDADeviceContext& dev_ctx_;
+  framework::Vector<int64_t> range_;
+};
+
 #endif
 
 }  // namespace platform
-- 
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