Set parallel count.

Author: mc-nv

tools/gen_ort_dockerfile.py

@@ -346,7 +346,8 @@ def dockerfile_for_linux(output_file):
 
     df += """
 WORKDIR /workspace/onnxruntime
-ARG COMMON_BUILD_ARGS="--config ${{ONNXRUNTIME_BUILD_CONFIG}} --skip_submodule_sync --parallel --build_shared_lib \
+ARG COMMON_BUILD_ARGS="--config ${{ONNXRUNTIME_BUILD_CONFIG}} --skip_submodule_sync \
+    --parallel  $(( $(nproc --all ) + 2 )) --build_shared_lib \
     --compile_no_warning_as_error --build_dir /workspace/build --cmake_extra_defines CMAKE_CUDA_ARCHITECTURES='{}'  --cmake_extra_defines CMAKE_POLICY_VERSION_MINIMUM=3.5 --build_wheel"
 """.format(
         cuda_archs