main.yml

---
# Automated setup of distributed Linpack benchmark.
#
# Inspired by: https://mikejmcfarlane.github.io/blog/2020/09/17/High-Performance-Linpack-for-raspberry-pi-supercomputer
# See also: https://www.sci-pi.org.uk/bench/linpack.html

- name: Install linpack benchmark.
  hosts: cluster
  become: false
  tags: ['setup']

  vars_files: ['config.yml']

  tasks:
    - name: Update apt cache.
      ansible.builtin.apt:
        update_cache: true
        cache_valid_time: 600
      when: ansible_os_family == 'Debian'
      become: true

    - name: Install dependencies.
      ansible.builtin.package:
        name:
          - build-essential
          - gfortran
          - automake
        state: present
      become: true

    - name: Create required temporary directories.
      ansible.builtin.file:
        path: "{{ item }}"
        state: directory
        owner: "{{ ansible_user | default(ansible_env.USER, true) | default(ansible_user_id, true) }}"
        group: "{{ ansible_user | default(ansible_env.USER, true) | default(ansible_user_id, true) }}"
        mode: 0755
      loop:
        - "{{ hpl_root }}/tmp"
        - "{{ hpl_root }}/tmp/atlas-build"
      become: true

    - name: Download MPI (Message Passing Interface).
      ansible.builtin.unarchive:
        src: https://www.mpich.org/static/downloads/3.4.2/mpich-3.4.2.tar.gz
        dest: "{{ hpl_root }}/tmp"
        remote_src: true
        creates: "{{ hpl_root }}/tmp/mpich-3.4.2/README"

    - name: Build MPI (takes a while).
      ansible.builtin.command: "{{ item }}"
      args:
        chdir: "{{ hpl_root }}/tmp/mpich-3.4.2"
        creates: "{{ hpl_root }}/tmp/COMPILE_MPI_COMPLETE"
      loop:
        - ./configure --with-device=ch3:sock FFLAGS=-fallow-argument-mismatch
        - "make -j{{ ansible_processor_nproc }}"

    - name: Install MPI.
      ansible.builtin.command: make install
      args:
        chdir: "{{ hpl_root }}/tmp/mpich-3.4.2"
        creates: "{{ hpl_root }}/tmp/COMPILE_MPI_COMPLETE"
      become: true

    - name: Create 'COMPILE_MPI_COMPLETE' file.
      file:
        path: "{{ hpl_root }}/tmp/COMPILE_MPI_COMPLETE"
        state: touch
        mode: 0644

    - name: Test if we can set CPU scaling parameters.
      ansible.builtin.command: >-
        ls /sys/devices/system/cpu/cpu0/cpufreq
      failed_when: false
      changed_when: false
      register: cpufreq_exists

    # Note: There was no simpler way to do this besides `shell`.
    - name: Ensure CPU scaling is set to 'performance'.
      ansible.builtin.shell: >-
        echo performance | sudo tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor
      when: cpufreq_exists.rc == 0

    - name: Download ATLAS linear algebra library.
      ansible.builtin.unarchive:
        src: https://sourceforge.net/projects/math-atlas/files/Stable/3.10.3/atlas3.10.3.tar.bz2
        dest: "{{ hpl_root }}/tmp"
        remote_src: true
        creates: "{{ hpl_root }}/tmp/ATLAS/README"

    - name: Install ATLAS (takes a LONG time).
      ansible.builtin.command: "{{ item }}"
      args:
        chdir: "{{ hpl_root }}/tmp/atlas-build"
        creates: "{{ hpl_root }}/tmp/COMPILE_ATLAS_COMPLETE"
      loop:
        - ../ATLAS/configure
        - make

    - name: Create 'COMPILE_ATLAS_COMPLETE' file.
      file:
        path: "{{ hpl_root }}/tmp/COMPILE_ATLAS_COMPLETE"
        state: touch
        mode: 0644

    - name: Download HPL (High Performance Linpack).
      ansible.builtin.unarchive:
        src: http://www.netlib.org/benchmark/hpl/hpl-2.3.tar.gz
        dest: "{{ hpl_root }}/tmp"
        remote_src: true
        creates: "{{ hpl_root }}/tmp/hpl-2.3/README"

    - name: Set up HPL makefile.
      ansible.builtin.shell: sh make_generic
      args:
        chdir: "{{ hpl_root }}/tmp/hpl-2.3/setup"
        creates: "{{ hpl_root }}/tmp/COMPILE_HPL_COMPLETE"

    - name: Copy rpi makefile into place.
      ansible.builtin.template:
        src: templates/benchmark-Make.rpi.j2
        dest: "{{ hpl_root }}/tmp/hpl-2.3/Make.rpi"
        mode: 0644

    - name: Install HPL.
      ansible.builtin.command: >-
        make arch=rpi
      args:
        chdir: "{{ hpl_root }}/tmp/hpl-2.3"
        creates: "{{ hpl_root }}/tmp/COMPILE_HPL_COMPLETE"

    - name: Create COMPILE_HPL_COMPLETE file.
      ansible.builtin.file:
        path: "{{ hpl_root }}/tmp/COMPILE_HPL_COMPLETE"
        state: touch
        mode: 0644

# See: https://github.com/geerlingguy/top500-benchmark/issues/1
- name: Configure SSH connections between nodes.
  hosts: cluster
  become: false
  tags: ['ssh']

  vars_files: ['config.yml']
  vars:
    host_ips: []

  tasks:
    - name: Generate an OpenSSH keypair.
      community.crypto.openssh_keypair:
        path: "{{ ssh_user_home }}/.ssh/id_rsa"
        size: 2048

    - name: Read out ssh pubkey from each host.
      ansible.builtin.command: cat "{{ ssh_user_home }}/.ssh/id_rsa.pub"
      changed_when: false
      register: ssh_pubkey

    - name: Combine pubkeys into single list.
      ansible.builtin.set_fact:
        combined_ssh_pubkeys: "{{ ansible_play_hosts | map('extract', hostvars, 'ssh_pubkey') | map(attribute='stdout') | list }}"
      run_once: true

    - name: Write all pubkeys to each host.
      ansible.posix.authorized_key:
        user: "{{ ssh_user }}"
        state: present
        key: "{{ item }}"
      loop: "{{ combined_ssh_pubkeys }}"

    - name: Generate list of host IP addresses.
      ansible.builtin.set_fact:
        host_ips: "{{ host_ips + [ hostvars[item].ansible_default_ipv4.address ] }}"
      loop: "{{ groups['cluster'] }}"

    - name: Accept hostkeys for each host on each host.
      ansible.builtin.command: >-
        ssh {{ ssh_user }}@{{ item }} -o StrictHostKeyChecking=accept-new date
      loop: "{{ host_ips }}"

    - name: Write chunk of hosts information to the hosts file.
      ansible.builtin.blockinfile:
        path: /etc/hosts
        marker: "# {mark} Ansible MPI host {{ item }}"
        block: |
          {{ hostvars[item].ansible_default_ipv4.address }} {{ item }} {{ item | replace('.local', '') }}
      loop: "{{ groups['cluster'] }}"
      become: true

- name: Run linpack benchmark.
  hosts: cluster
  become: false
  tags: ['benchmark']

  vars_files: ['config.yml']

  tasks:
    - name: Create a file describing nodes for MPI execution.
      ansible.builtin.template:
        src: templates/mpi-node-config.j2
        dest: "{{ hpl_root }}/tmp/hpl-2.3/bin/rpi/cluster-hosts"
        mode: 0644

    # Template originally generated using this website:
    # https://www.advancedclustering.com/act_kb/tune-hpl-dat-file/
    - name: Create HPL.dat file.
      ansible.builtin.template:
        src: templates/HPL.dat.j2
        dest: "{{ hpl_root }}/tmp/hpl-2.3/bin/rpi/HPL.dat"
        mode: 0644

    - name: Run the benchmark.
      ansible.builtin.command: mpirun -f cluster-hosts ./xhpl
      args:
        chdir: "{{ hpl_root }}/tmp/hpl-2.3/bin/rpi"
      register: mpirun_output
      run_once: true

    - name: Output the results.
      debug: var=mpirun_output.stdout