A-FOT Configuration File Parameter Optimization

Procedure

The following procedure explains how to optimize parameters in the configuration file.

1. Before using the A-FOT tool, move ${HOME}/.local/gcc-10.3.1-2023.12-aarch64-linux/bin to the beginning of the PATH environment variable. Example:

   export PATH=${HOME}/.local/gcc-10.3.1-2023.12-aarch64-linux/bin:$PATH

2. Locate the a-fot.ini file in the A-FOT root directory and set the configuration items.

   vi ${HOME}/.local/a-fot/a-fot.ini

   File content:

   # Use absolute paths for files and directories.
   # Optimization mode, which is AutoFDO, AutoPrefetch, AutoBOLT, or Auto_kernel_PGO.
   opt_mode=AutoPrefetch
   #Script working directory, used to compile the application and store profiles and logs.
   work_path=/opt
   # Application running script path: run_script=/root/run.sh.
   # GCC path, which is the parent directory of bin and lib.
   gcc_path=/usr 
   # AutoFDO, AutoPrefetch, AutoBOLT
   # Configure the three optimization modes for the application.
   # Application process name.
   application_name=test
   # Executable file after binary installation.
   bin_file=/tmp/test
   # Application build script path: build_script=/root/build.sh.
   # Maximum binary startup time, in seconds.
   max_waiting_time=600
   # Perf sampling duration, in seconds.
   perf_time=100
   # Checks whether the optimization is successful (1: enabled; 0: disabled).
   check_success=0
   # Build mode, which is Bear or Wrapper.
   build_mode=Wrapper 
   # auto_kernel_PGO # Set the kernel optimization mode.
   # Kernel PGO mode. (arc: enables only the arc profile; all: enables full PGO.)
   pgo_mode=all
   # Execution stage. (1: stage of compiling and instrumenting the kernel; 2: stage of compiling and optimizing)
   pgo_phase=1
   # Kernel source code directory. If this directory is not specified, the kernel source code is automatically downloaded.
   kernel_src=/opt/kernel
   # Local name of the kernel build. The tool will add the -pgoing or -pgoed suffix depending on the stage.
   kernel_name=kernel
   # Kernel compilation options. Ensure that the options are correct and valid. Otherwise, the kernel compilation will fail. #CONFIG_...=y
   # Timestamped directory created before restart, used to store logs from the same workflow together.
   last_time=
   # Kernel source Makefile address, used when the kernel is not automatically compiled.
   makefile=
   # Kernel configuration file address, used when the kernel is not automatically compiled.
   kernel_config=
   # Directory of the original profile generated by the kernel, used when the kernel is not automatically compiled.
   data_dir=

   In the configuration file, the script working directory is in the /opt directory. Change it to the home directory or ./ based on your requirements.

3. Run the following command to start optimization:

   a-fot --config_file a-fot.ini