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name: Tune Runner VM performance
description: tunes the GitHub Runner VM operation system
runs:
  using: composite
  steps:
    - run: |
        if [[ "$OSTYPE" == "linux-gnu"* ]]; then
            echo "::group::Configure and tune OS"
            # Ensure that reverse lookups for current hostname are handled properly
            # Add the current IP address, long hostname and short hostname record to /etc/hosts file
            echo -e "$(ip addr show eth0 | grep "inet\b" | awk '{print $2}' | cut -d/ -f1)\t$(hostname -f) $(hostname -s)" | sudo tee -a /etc/hosts

            # The default vm.swappiness setting is 60 which has a tendency to start swapping when memory
            # consumption is high.
            # Set vm.swappiness=1 to avoid swapping and allow high RAM usage
            echo 1 | sudo tee /proc/sys/vm/swappiness
            (
              shopt -s nullglob
              # Set swappiness to 1 for all cgroups and sub-groups
              for swappiness_file in /sys/fs/cgroup/memory/*/memory.swappiness /sys/fs/cgroup/memory/*/*/memory.swappiness; do
                echo 1 | sudo tee $swappiness_file > /dev/null
              done
            ) || true

            # use "madvise" Linux Transparent HugePages (THP) setting
            # https://www.kernel.org/doc/html/latest/admin-guide/mm/transhuge.html
            # "madvise" is generally a better option than the default "always" setting
            # Based on Azul instructions from https://docs.azul.com/prime/Enable-Huge-Pages#transparent-huge-pages-thp
            echo madvise | sudo tee /sys/kernel/mm/transparent_hugepage/enabled
            echo advise | sudo tee /sys/kernel/mm/transparent_hugepage/shmem_enabled
            echo defer+madvise | sudo tee /sys/kernel/mm/transparent_hugepage/defrag
            echo 1 | sudo tee /sys/kernel/mm/transparent_hugepage/khugepaged/defrag
    
            # tune filesystem mount options, https://www.kernel.org/doc/Documentation/filesystems/ext4.txt
            # commit=999999, effectively disables automatic syncing to disk (default is every 5 seconds)
            # nobarrier/barrier=0, loosen data consistency on system crash (no negative impact to empheral CI nodes)
            sudo mount -o remount,nodiscard,commit=999999,barrier=0 / || true
            sudo mount -o remount,nodiscard,commit=999999,barrier=0 /mnt || true
            # disable discard/trim at device level since remount with nodiscard doesn't seem to be effective
            # https://www.spinics.net/lists/linux-ide/msg52562.html
            for i in /sys/block/sd*/queue/discard_max_bytes; do
              echo 0 | sudo tee $i
            done
            # disable any background jobs that run SSD discard/trim
            sudo systemctl disable fstrim.timer || true
            sudo systemctl stop fstrim.timer || true
            sudo systemctl disable fstrim.service || true
            sudo systemctl stop fstrim.service || true

            # stop php-fpm
            sudo systemctl stop php8.0-fpm.service || true
            sudo systemctl stop php7.4-fpm.service || true
            # stop mono-xsp4
            sudo systemctl disable mono-xsp4.service || true
            sudo systemctl stop mono-xsp4.service || true
            sudo killall mono || true

            # stop Azure Linux agent to save RAM
            sudo systemctl stop walinuxagent.service || true
          
            echo '::endgroup::'

            # show memory
            echo "::group::Available Memory"
            free -m
            echo '::endgroup::'
            # show disk
            echo "::group::Available diskspace"
            df -BM
            echo "::endgroup::"
            # show cggroup
            echo "::group::Cgroup settings for current cgroup $CURRENT_CGGROUP"
            CURRENT_CGGROUP=$(cat /proc/self/cgroup | grep '0::' | awk -F: '{ print $3 }')
            sudo cgget -a $CURRENT_CGGROUP || true
            echo '::endgroup::'
        fi
      shell: bash