Add gpu profiling docs

doc/index.md

@@ -17,6 +17,7 @@ Development Guide
 * [Layer Documents](layer.md)
 * [Writing New Layers](dev/new_layer/index.rst)
 * [Source Code Documents](source/index.md)
+* [GPU Profiling Documents](optimization/index.rst)
 
 Algorithm Tutorial
 ------------------

doc/optimization/gpu_profiling.rst

+GPU Profiling
+=============
+
+This tutorial will guide you step-by-step through how to conduct profiling and performance tuning using :code:`nvprof` and :code:`nvvp`.
+
+- What is profiling?
+- Why we need profiling?
+- How to do profiling?
+- Profile tools
+- Hands-on Tutorial
+
+What's profiling?
+=================
+In software engineering, profiling is a form of dynamic program analysis that measures the space (memory) or time
+complexity of a program, the usage of particular instructions, or the frequency and duration of function calls.
+Most commonly, profiling information serves to aid program optimization.
+
+Briefly, profiler is used to measure application performance. Program analysis tools are extremely important for
+understanding program behavior. Simple profiling can tell you that how long does an operation take? For advanced
+profiling, it can interpret why does an operation take a long time?
+
+Why we need profiling?
+======================
+Since training deep neural network typically take a very long time to get over, performance is gradually becoming
+the most important thing in deep learning field. The first step to improve performance is to understand what parts
+are slow. No point in improving performance of a region which doesn’t take much time!
+
+
+How to do profiling?
+====================
+To achieve maximum performance, there are five steps you can take to reach your goals.
+
+- Profile the code
+- Find the slow parts
+- Work out why they’re slow
+- Make them fast
+- Profile the code again
+
+Usually, processor has two key performance limits include float point throughput and
+memory throughput. For GPU,  it also need more parallelism to fulfill its potential.
+This is why they can be so fast.
+
+Profiler Tools
+==============
+For general GPU profiling, a bunch of tools are provided from both NVIDIA and third party.
+
+:code:`nvprof` is Nvidia profiler and :code:`nvvp` is (GUI based) Nvidia visual profiler.
+In this tutorial, we will focus on nvprof and nvvp.
+
+:code:`test_GpuProfiler` from :code:`paddle/math/tests` directory will be used to evaluate
+above profilers. 
+
+.. code-block:: c++
+
+    TEST(Profiler, BilinearFwdBwd) {
+        hl_profiler_start();
+        auto numSamples = 10;
+        auto channels = 16;
+        auto imgSize = 64;
+        testBilinearFwdBwd(numSamples, imgSize, imgSize, channels);
+        hl_profiler_end();
+    }
+
+:code:`hl_profiler_start` and :code:`hl_profiler_end` can be used to profile only regions of interest
+in PaddlePaddle. They are wrapper functions of :code:`cudaProfilerStart` and :code:`cudaProfilerStop`
+respectively to avoid program crashes when CPU version of PaddlePaddle invokes them.
+
+Hands-on Approach
+=================
+
+..  image:: nvprof.png
+    :align: center
+    :scale: 30%
+
+..  image:: nvvp1.png
+    :align: center
+    :scale: 30%
\ No newline at end of file

doc/optimization/index.rst

+Performance Tuning
+==================
+
+.. toctree::
+  :maxdepth: 3
+
+  gpu_profiling.rst