Tidy CUDA memory mode Makefile

CUDA.make

@@ -1,8 +1,38 @@
 CXXFLAGS=-O3
 CUDA_CXX=nvcc
 
+
+ifndef NVARCH
+define nvarch_help
+Set NVARCH to select sm_?? version.
+Default: sm_60
+
+endef
+$(info $(nvarch_help))
+NVARCH=sm_60
+endif
+
+
+ifndef MEM
+define mem_help
+Set MEM to select memory mode.
+Available options:
+  DEFAULT   - allocate host and device memory pointers.
+  MANAGED   - use CUDA Managed Memory.
+  PAGEFAULT - shared memory, only host pointers allocated.
+
+endef
+$(info $(mem_help))
+MEM=DEFAULT
+endif
+
+MEM_MANAGED= -DMANAGED
+MEM_PAGEFAULT= -DPAGEFAULT
+MEM_MODE = $(MEM_$(MEM))
+
+
 cuda-stream: main.cpp CUDAStream.cu
-	$(CUDA_CXX) -std=c++11 $(CXXFLAGS) -DCUDA $^ $(EXTRA_FLAGS) -o $@
+	$(CUDA_CXX) -std=c++11 $(CXXFLAGS) -arch=$(NVARCH) $(MEM_MODE) -DCUDA $^ $(EXTRA_FLAGS) -o $@
 
 .PHONY: clean
 clean: