Add some docs for Profiler

README.md

@@ -11,6 +11,10 @@ such as computation graph, training process metrics, etc.
     Provide visualization of model parameters information, 
 such as training data, model accuracy, etc.
 
+- Visualization of training performance:
+
+    Provide visualization of training performance information, such as operator execution time,
+data input pipeline performance, etc.
 
 # Index
 
@@ -91,6 +95,10 @@ The GUI of MindInsight displays the pipeline of dataset processing and augmentat
 
 The GUI of MindInsight displays the parameters and operations of the dataset processing and augmentation.
 
+### Performance visualization
+
+The GUI of MindInsight displays the performance data of the neural networks.
+
 # Installation
 
 See [Install MindInsight](https://www.mindspore.cn/install/en).

mindinsight/profiler/README.md

@@ -65,8 +65,8 @@ Figure 2 displays the Step Trace page. The Step Trace detail will show the start
 can also choose a specific step to see its step trace statistics. The graphs at the bottom of the page show how the execution time of Step Gap, Forward/Backward Propagation and
 Step Tail changes according to different steps, it will help to decide whether we can optimize the performance of some stages.
 
-*Notice:* MindSpore choose the Foward Start/Backward End Operators automatically, The names of the two operators are shown on the page. It is possible that the two operators are
-not choosen as what the user expect. Users can choose the operators from the dumped execution graph, and specify the two operators manually by setting the `FP_POINT` and `BP_POINT` environment. 
+*Notice:* MindSpore choose the Foward Start/Backward End Operators automatically, The names of the two operators are shown on the page. Profiler do not guarantee that the two operators are
+always chosen as the user's expectation. Users can choose the two operators according to the execution graph, and specify the them manually by setting the `FP_POINT` and `BP_POINT` environment variables.
 For example: `export FP_POINT=fp32_vars/conv2d/conv2Dfp32_vars/BatchNorm/FusedBatchNorm_Reduce` and `export BP_POINT=loss_scale/gradients/AddN_70`. 
 
 ### Operator Performance Analysis
@@ -160,3 +160,5 @@ The Profiler has the following limitations now:
 
 * Only programs running on Ascend chip is supported.
 * To limit the data size generated by the Profiler, MindInsight suggests that for large neural network, the profiled steps should better below 10.
+* The parse of Timeline data is time consuming, and several step's data is usually enough for analysis. In order to speed up the data parse and UI
+display, Profiler will show at most 20M data (Contain 10+ step information for large networks).