add TensorRT_Dynamic_Shape_EN.md

doc/TensorRT_Dynamic_Shape_EN.md

+# How to configure TensorRT dynamic shape
+([简体中文](./TensorRT_Dynamic_Shape_CN.md)|English)
+
+## Overview
+
+After enabling TensorRT `--use_trt` in Pipeline/C++. Regarding how to configure the dynamic shape, the following will give examples of Pipeline Serving and C++ Serving respectively
+
+The following is the dynamic shape api
+```
+  void SetTRTDynamicShapeInfo(
+      std::map<std::string, std::vector<int>> min_input_shape,
+      std::map<std::string, std::vector<int>> max_input_shape,
+      std::map<std::string, std::vector<int>> optim_input_shape,
+      bool disable_trt_plugin_fp16 = false);
+```
+For detail, please refer to API doc [C++](https://paddleinference.paddlepaddle.org.cn/api_reference/cxx_api_doc/Config/GPUConfig.html#tensorrt)/[Python](https://paddleinference.paddlepaddle.org.cn/api_reference/python_api_doc/Config/GPUConfig.html#tensorrt)
+
+### C++ Serving
+Modify the following code in `**/paddle_inference/paddle/include/paddle_engine.h`
+
+```
+    if (engine_conf.has_use_trt() && engine_conf.use_trt()) {
+      config.SwitchIrOptim(true);
+      if (!engine_conf.has_use_gpu() || !engine_conf.use_gpu()) {
+        config.EnableUseGpu(50, gpu_id);
+        if (engine_conf.has_gpu_multi_stream() &&
+            engine_conf.gpu_multi_stream()) {
+          config.EnableGpuMultiStream();
+        }
+      }
+      config.EnableTensorRtEngine((1 << 30) + (1 << 29),
+                                  max_batch,
+                                  min_subgraph_size,
+                                  precision_type,
+                                  true,
+                                  FLAGS_use_calib);
+      // set trt dynamic shape
+      {
+        int bsz = 1;
+        int max_seq_len = 512;
+        std::map<std::string, std::vector<int>> min_input_shape;
+        std::map<std::string, std::vector<int>> max_input_shape;
+        std::map<std::string, std::vector<int>> optim_input_shape;
+        int hidden_size = 0;
+
+        min_input_shape["stack_0.tmp_0"] = {1, 16, 1, 1};
+        min_input_shape["stack_1.tmp_0"] = {1, 2, 1, 1};
+        min_input_shape["input_mask"] = {1, 1, 1};
+        min_input_shape["_generated_var_64"] = {1, 1, 768};
+        min_input_shape["fc_0.tmp_0"] = {1, 1, 768};
+        min_input_shape["_generated_var_87"] = {1, 1, 768};
+        min_input_shape["tmp_175"] = {1, 1, 768};
+        min_input_shape["c_allreduce_sum_0.tmp_0"] = {1,1, 12288};
+        min_input_shape["embedding_1.tmp_0"] = {1, 1, 12288};
+
+
+        max_input_shape["stack_0.tmp_0"] = {bsz, 16, max_seq_len, max_seq_len};
+        max_input_shape["stack_1.tmp_0"] = {bsz, 2, max_seq_len, max_seq_len};
+        max_input_shape["input_mask"] = {bsz, max_seq_len, max_seq_len};
+        max_input_shape["_generated_var_64"] = {bsz, max_seq_len, 768};
+        max_input_shape["fc_0.tmp_0"] = {bsz, max_seq_len, 768};
+        max_input_shape["_generated_var_87"] = {bsz, max_seq_len, 768};
+        max_input_shape["tmp_175"] = {bsz, max_seq_len, 768};
+        max_input_shape["c_allreduce_sum_0.tmp_0"] = {bsz,max_seq_len, 12288};
+        max_input_shape["embedding_1.tmp_0"] = {bsz, max_seq_len, 12288};
+
+        int g1 = 0;
+        int g2 = 0;
+        int t1 = 0;
+        int t2 = 0;
+        std::string var_name = "_generated_var_";
+        std::string tmp_name = "tmp_";
+        for (int i = 0; i < 44; ++i) {
+          if (i > 32) {
+            hidden_size = 768;
+            g1 = 2*i-1;
+            g2 = 2*i;
+            t1 = 4*i-1;
+            t2 = 4*i;
+            min_input_shape[var_name+std::to_string(g1)] = {1, 1, hidden_size};
+            min_input_shape[var_name+std::to_string(g2)] = {1, 1, hidden_size};
+            min_input_shape[tmp_name+std::to_string(t1)] = {1, 1, hidden_size};
+            min_input_shape[tmp_name+std::to_string(t2)] = {1, 1, hidden_size};
+            max_input_shape[var_name+std::to_string(g1)] = {bsz, max_seq_len, hidden_size};
+            max_input_shape[var_name+std::to_string(g2)] = {bsz, max_seq_len, hidden_size};
+            max_input_shape[tmp_name+std::to_string(t1)] = {bsz, max_seq_len, hidden_size};
+            max_input_shape[tmp_name+std::to_string(t2)] = {bsz, max_seq_len, hidden_size};
+          }
+          if (i <32) {
+            hidden_size = 12288;
+            g1 = 2*i;
+            g2 = 2*i+1;
+            t1 = 4*i;
+            t2 = 4*i+3;
+            min_input_shape[var_name+std::to_string(g1)] = {1, 1, hidden_size};
+            min_input_shape[var_name+std::to_string(g2)] = {1, 1, hidden_size};
+            min_input_shape[tmp_name+std::to_string(t1)] = {1, 1, hidden_size};
+            min_input_shape[tmp_name+std::to_string(t2)] = {1, 1, hidden_size};
+            max_input_shape[var_name+std::to_string(g1)] = {bsz, max_seq_len, hidden_size};
+            max_input_shape[var_name+std::to_string(g2)] = {bsz, max_seq_len, hidden_size};
+            max_input_shape[tmp_name+std::to_string(t1)] = {bsz, max_seq_len, hidden_size};
+            max_input_shape[tmp_name+std::to_string(t2)] = {bsz, max_seq_len, hidden_size};
+          }
+        }
+        optim_input_shape = max_input_shape;
+        config.SetTRTDynamicShapeInfo(
+        min_input_shape, max_input_shape, optim_input_shape);
+      }
+      LOG(INFO) << "create TensorRT predictor";
+    }
+```
+
+
+### Pipeline Serving
+
+Modify the following code in `**/python/paddle_serving_app/local_predict.py`
+
+```
+if use_trt:
+    config.enable_tensorrt_engine(
+        precision_mode=precision_type,
+        workspace_size=1 << 20,
+        max_batch_size=32,
+        min_subgraph_size=3,
+        use_static=False,
+        use_calib_mode=False)
+    head_number = 12
+
+    names = [
+        "placeholder_0", "placeholder_1", "placeholder_2", "stack_0.tmp_0"
+    ]
+    min_input_shape = [1, 1, 1]
+    max_input_shape = [100, 128, 1]
+    opt_input_shape = [10, 60, 1]
+
+    config.set_trt_dynamic_shape_info(
+        {
+            names[0]: min_input_shape,
+            names[1]: min_input_shape,
+            names[2]: min_input_shape,
+            names[3]: [1, head_number, 1, 1]
+        }, {
+            names[0]: max_input_shape,
+            names[1]: max_input_shape,
+            names[2]: max_input_shape,
+            names[3]: [100, head_number, 128, 128]
+        }, {
+            names[0]: opt_input_shape,
+            names[1]: opt_input_shape,
+            names[2]: opt_input_shape,
+            names[3]: [10, head_number, 60, 60]
+        })
+                
+```
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