[PyTorch] add cuDNN acceleration

docs/development/inference_performance_optimization.md

@@ -61,6 +61,17 @@ You can enable it by
 
 You might see the exception if certain data type or operator is not supported with the oneDNN device.
 
+#### CuDNN acceleration
+PyTorch has a special flags that used for CNN or related network speed up. If your input size won't change frequently,
+you may benefit from enabling this configuration in your model:
+
+```
+-Dai.djl.pytorch.cudnn_benchmark=true
+```
+
+If your input shape changed frequently, this change may stall your performance. For more information, check this 
+[article](https://pytorch.org/tutorials/recipes/recipes/tuning_guide.html#enable-cudnn-auto-tuner).
+
 #### Thread configuration
 There are two configurations you can set to optimize the inference performance.
 

engines/pytorch/pytorch-engine/src/main/java/ai/djl/pytorch/engine/PtEngine.java

@@ -55,6 +55,10 @@ static Engine newInstance() {
             if (Integer.getInteger("ai.djl.pytorch.num_threads") != null) {
                 JniUtils.setNumThreads(Integer.getInteger("ai.djl.pytorch.num_threads"));
             }
+            // for ConvNN related model speed up
+            if (Boolean.getBoolean("ai.djl.pytorch.cudnn_benchmark")) {
+                JniUtils.setBenchmarkCuDNN(true);
+            }
             logger.info("Number of inter-op threads is " + JniUtils.getNumInteropThreads());
             logger.info("Number of intra-op threads is " + JniUtils.getNumThreads());
 

engines/pytorch/pytorch-engine/src/main/java/ai/djl/pytorch/jni/JniUtils.java

@@ -84,6 +84,10 @@ public static void setNumThreads(int threads) {
         PyTorchLibrary.LIB.torchSetNumThreads(threads);
     }
 
+    public static void setBenchmarkCuDNN(boolean enable) {
+        PyTorchLibrary.LIB.torchSetBenchmarkCuDNN(enable);
+    }
+
     public static synchronized Set<String> getFeatures() {
         if (configs != null) {
             return configs;

engines/pytorch/pytorch-engine/src/main/java/ai/djl/pytorch/jni/PyTorchLibrary.java

@@ -32,6 +32,8 @@ private PyTorchLibrary() {}
 
     native void torchSetNumThreads(int threads);
 
+    native void torchSetBenchmarkCuDNN(boolean enable);
+
     native void torchManualSeed(long seed);
 
     native void torchShowConfig(Set<String> set);

engines/pytorch/pytorch-native/src/main/native/ai_djl_pytorch_jni_PyTorchLibrary_inference.cc

@@ -161,6 +161,13 @@ JNIEXPORT void JNICALL Java_ai_djl_pytorch_jni_PyTorchLibrary_setGraphExecutorOp
   API_END()
 }
 
+JNIEXPORT void JNICALL Java_ai_djl_pytorch_jni_PyTorchLibrary_torchSetBenchmarkCuDNN(
+        JNIEnv* env, jobject jthis, jboolean jenabled) {
+    API_BEGIN()
+    torch::globalContext().setBenchmarkCuDNN(jenabled);
+    API_END()
+}
+
 JNIEXPORT void JNICALL Java_ai_djl_pytorch_jni_PyTorchLibrary_moduleEval(
     JNIEnv* env, jobject jthis, jlong module_handle) {
   API_BEGIN()