Replace hardcoded cmake --build -j flags in docs and scripts

mac: $(sysctl -n hw.ncpu) - 1
linux: $(nproc) - 1

Author: MichaelIspas

.ci/docker/common/install_openssl.sh

@@ -17,7 +17,7 @@ tar xf "${OPENSSL}.tar.gz"
 pushd "${OPENSSL}" || true
 ./config --prefix=/opt/openssl -d "-Wl,--enable-new-dtags,-rpath,$(LIBRPATH)"
 # NOTE: openssl install errors out when built with the -j option
-make -j6; make install_sw
+make -j$((nproc) - 1); make install_sw
 # Link the ssl libraries to the /usr/lib folder.
 ln -s /opt/openssl/lib/lib* /usr/lib
 popd || true

.ci/scripts/build-qnn-sdk.sh

@@ -35,7 +35,7 @@ set_up_aot() {
       -DEXECUTORCH_BUILD_EXTENSION_TENSOR=ON \
       -DEXECUTORCH_ENABLE_EVENT_TRACER=ON \
       -DPYTHON_EXECUTABLE=python3
-  cmake --build $PWD --target "PyQnnManagerAdaptor" "PyQnnWrapperAdaptor" -j$(nproc)
+  cmake --build $PWD --target "PyQnnManagerAdaptor" "PyQnnWrapperAdaptor" -j$((nproc) -1)
   # install Python APIs to correct import path
   # The filename might vary depending on your Python and host version.
   cp -f backends/qualcomm/PyQnnManagerAdaptor.cpython-310-x86_64-linux-gnu.so $EXECUTORCH_ROOT/backends/qualcomm/python

.ci/scripts/build_llama_android.sh

@@ -31,7 +31,7 @@ install_executorch_and_backend_lib() {
     -DXNNPACK_ENABLE_ARM_BF16=OFF \
     -Bcmake-android-out .
 
-  cmake --build cmake-android-out -j4 --target install --config Release
+  cmake --build cmake-android-out -j$((nproc) -1) --target install --config Release
 }
 
 build_llama_runner() {
@@ -48,7 +48,7 @@ build_llama_runner() {
     -DCMAKE_BUILD_TYPE=Release \
     -Bcmake-android-out/examples/models/llama examples/models/llama
 
-    cmake --build cmake-android-out/examples/models/llama -j4 --config Release
+    cmake --build cmake-android-out/examples/models/llama -j$((nproc) -1) --config Release
 }
 install_executorch_and_backend_lib
 build_llama_runner

.ci/scripts/setup-openvino.sh

@@ -16,7 +16,7 @@ git submodule update --init --recursive
 sudo ./install_build_dependencies.sh
 mkdir build && cd build
 cmake .. -DCMAKE_BUILD_TYPE=Release -DENABLE_PYTHON=ON
-make -j$(nproc)
+make -j$((nproc) -1)
 
 cd ..
 cmake --install build --prefix dist

.ci/scripts/test_llama.sh

@@ -158,7 +158,7 @@ cmake_install_executorch_libraries() {
         -DEXECUTORCH_BUILD_QNN="$QNN" \
         -DQNN_SDK_ROOT="$QNN_SDK_ROOT" \
         -Bcmake-out .
-    cmake --build cmake-out -j9 --target install --config "$CMAKE_BUILD_TYPE"
+    cmake --build cmake-out -j$(($(nproc) - 1)) --target install --config "$CMAKE_BUILD_TYPE"
 }
 
 cmake_build_llama_runner() {
@@ -173,7 +173,7 @@ cmake_build_llama_runner() {
         -DCMAKE_BUILD_TYPE="$CMAKE_BUILD_TYPE" \
         -Bcmake-out/${dir} \
         ${dir}
-    cmake --build cmake-out/${dir} -j9 --config "$CMAKE_BUILD_TYPE"
+    cmake --build cmake-out/${dir} -j$(($(nproc) - 1)) --config "$CMAKE_BUILD_TYPE"
 
 }
 

.ci/scripts/test_llama_torchao_lowbit.sh

@@ -36,7 +36,7 @@ cmake -DPYTHON_EXECUTABLE=python \
     -DEXECUTORCH_BUILD_KERNELS_OPTIMIZED=ON \
     -DEXECUTORCH_BUILD_KERNELS_CUSTOM=ON \
     -Bcmake-out .
-cmake --build cmake-out -j16 --target install --config Release
+cmake --build cmake-out -j$(( $(nproc) - 1 )) --target install --config Release
 
 # Install llama runner with torchao
 cmake -DPYTHON_EXECUTABLE=python \
@@ -49,7 +49,7 @@ cmake -DPYTHON_EXECUTABLE=python \
     -DEXECUTORCH_BUILD_TORCHAO=ON \
     -Bcmake-out/examples/models/llama \
     examples/models/llama
-cmake --build cmake-out/examples/models/llama -j16 --config Release
+cmake --build cmake-out/examples/models/llama -j$(($(nproc) - 1)) --config Release
 
 # Download stories llama110m artifacts
 download_stories_model_artifacts

.ci/scripts/test_model.sh

@@ -59,13 +59,13 @@ build_cmake_executor_runner() {
       && cmake -DCMAKE_BUILD_TYPE=Release \
         -DEXECUTORCH_BUILD_XNNPACK=ON \
         -DPYTHON_EXECUTABLE="$PYTHON_EXECUTABLE" ..)
-    cmake --build ${CMAKE_OUTPUT_DIR} -j4
+    cmake --build ${CMAKE_OUTPUT_DIR} -j$(($(nproc) - 1))
   else
     cmake -DCMAKE_BUILD_TYPE=Debug \
         -DEXECUTORCH_BUILD_KERNELS_OPTIMIZED=ON \
         -DPYTHON_EXECUTABLE="$PYTHON_EXECUTABLE" \
         -B${CMAKE_OUTPUT_DIR} .
-    cmake --build ${CMAKE_OUTPUT_DIR} -j4 --config Debug
+    cmake --build ${CMAKE_OUTPUT_DIR} -j$(($(nproc) - 1)) --config Debug
   fi
 }
 

.ci/scripts/test_quantized_aot_lib.sh

@@ -23,7 +23,7 @@ build_cmake_quantized_aot_lib() {
       -DEXECUTORCH_BUILD_KERNELS_QUANTIZED_AOT=ON \
       -DPYTHON_EXECUTABLE="$PYTHON_EXECUTABLE" ..)
 
-  cmake --build ${CMAKE_OUTPUT_DIR} -j4
+  cmake --build ${CMAKE_OUTPUT_DIR} -j$(($(nproc) - 1))
 }
 
 build_cmake_quantized_aot_lib

.ci/scripts/utils.sh

@@ -141,7 +141,7 @@ build_executorch_runner_cmake() {
   else
     CMAKE_JOBS=$(( $(nproc) - 1 ))
   fi
-  cmake --build "${CMAKE_OUTPUT_DIR}" -j "${CMAKE_JOBS}"
+  cmake --build "${CMAKE_OUTPUT_DIR}" -j$((nproc) -1) "${CMAKE_JOBS}"
 }
 
 build_executorch_runner() {
@@ -162,7 +162,7 @@ cmake_install_executorch_lib() {
           -DCMAKE_BUILD_TYPE=Release \
           -DPYTHON_EXECUTABLE="$PYTHON_EXECUTABLE" \
           -Bcmake-out .
-  cmake --build cmake-out -j9 --target install --config Release
+  cmake --build cmake-out -j$(($(nproc) - 1)) --target install --config Release
 }
 
 download_stories_model_artifacts() {

.github/workflows/trunk.yml

@@ -561,7 +561,7 @@ jobs:
           -DEXECUTORCH_BUILD_DEVTOOLS=ON \
           -DEXECUTORCH_ENABLE_EVENT_TRACER=ON \
           -Bcmake-out .
-        cmake --build cmake-out -j16 --target install --config Release
+        cmake --build cmake-out -j$(($(sysctl -n hw.ncpu) - 1))  --target install --config Release
         echo "::endgroup::"
 
         echo "::group::Set up Hugging Face"