Cudnn update to 7.4.2 + warn if old version is used with RTX cards (#741

)

* move cuda info display earlier

* warn if cudnn older than 7.3.1 is used with rtx cards

* update cudnn to 7.4.2

appveyor.yml

@@ -28,8 +28,8 @@ install:
 - cmd: IF DEFINED CUDA_INSTALL appveyor DownloadFile https://developer.nvidia.com/compute/cuda/10.0/Prod/network_installers/cuda_10.0.130_win10_network
 - cmd: IF DEFINED CUDA_INSTALL cuda_10.0.130_win10_network -s nvcc_10.0 cublas_dev_10.0 cublas_10.0 cudart_10.0
 - cmd: IF %CUDA%==true set PATH=%CUDA_PATH%\bin;%PATH%
-- cmd: IF %CUDA%==true IF NOT EXIST C:\cache\cuda appveyor DownloadFile http://developer.download.nvidia.com/compute/redist/cudnn/v7.3.1/cudnn-10.0-windows10-x64-v7.3.1.20.zip
-- cmd: IF %CUDA%==true IF NOT EXIST C:\cache\cuda 7z x cudnn-10.0-windows10-x64-v7.3.1.20.zip -oC:\cache
+- cmd: IF %CUDA%==true IF NOT EXIST C:\cache\cuda appveyor DownloadFile http://developer.download.nvidia.com/compute/redist/cudnn/v7.4.2/cudnn-10.0-windows10-x64-v7.4.2.24.zip
+- cmd: IF %CUDA%==true IF NOT EXIST C:\cache\cuda 7z x cudnn-10.0-windows10-x64-v7.4.2.24.zip -oC:\cache
 - cmd: set PATH=C:\Python36;C:\Python36\scripts;%PATH%
 - cmd: pip3 install --upgrade meson
 - cmd: call "C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Auxiliary\Build\vcvarsall.bat" amd64

src/neural/cuda/network_cudnn.cc

@@ -174,16 +174,16 @@ class CudnnNetwork : public Network {
     if (gpu_id_ >= total_gpus)
       throw Exception("Invalid GPU Id: " + std::to_string(gpu_id_));
 
+    cudaDeviceProp deviceProp = {};
+    cudaGetDeviceProperties(&deviceProp, gpu_id_);
+    showInfo(deviceProp);
+
     // Select GPU to run on (for *the current* thread).
     ReportCUDAErrors(cudaSetDevice(gpu_id_));
 
     ReportCUDNNErrors(cudnnCreate(&cudnn_));
     ReportCUBLASErrors(cublasCreate(&cublas_));
 
-    cudaDeviceProp deviceProp = {};
-    cudaGetDeviceProperties(&deviceProp, gpu_id_);
-    showInfo(deviceProp);
-
     if (std::is_same<half, DataType>::value) {
       // Check if the GPU support fp16 (Volta+).
       if (deviceProp.major >= 7) {
@@ -728,10 +728,14 @@ class CudnnNetwork : public Network {
     pl = version - major * 1000 - minor * 100;
     CERR << "Cudnn version: " << major << "." << minor << "." << pl;
     if (version != CUDNN_VERSION) {
-      CERR << "WARNING: CUDA Runtime version mismatch, was compiled with "
+      CERR << "WARNING: CUDNN Runtime version mismatch, was compiled with "
               "version "
            << CUDNN_MAJOR << "." << CUDNN_MINOR << "." << CUDNN_PATCHLEVEL;
     }
+    if (version < 7301 && (deviceProp.major > 7 ||
+                           (deviceProp.major == 7 && deviceProp.minor >= 5))) {
+      CERR << "WARNING: CUDNN version 7.3.1 or newer is better for this GPU.";
+    }
     cudaDriverGetVersion(&version);
     major = version / 1000;
     minor = (version - major * 1000) / 10;