MPI Plugin User Guide

Introduction

MPI plugin is designed to optimize the user experience when running MPI jobs, it not only allows users to write less yaml, but also ensures the normal operation of MPI jobs.

How the MPI Plugin Works

The MPI plugin will do three things:

• Open ports used by MPI for all containers of the job
• Force open ssh and svc plugins
• add MPI_HOST environment variable for master pod, this environment variable includes the worker's domain name, It is used by the --host parameter of mpiexec

Parameters of the MPI Plugin

Key Points

• If master or worker is configured, please ensure that the tasks corresponding to their values exist, and the roles of these tasks correspond to the meaning of the parameters
• If port is configured, make the port value of sshd the same as the value of the parameter.
• If the gang plugin is enabled, then make sure that the value of minAvailable is equal to the number of replicas of the worker.

Arguments

ID	Name	Type	Default Value	Required	Description	Example
1	master	string	master	No	Name of MPI master	--master=mpimaster
2	worker	string	worker	No	Name of MPI worker	--worker=mpiworker
3	port	string	22	No	The port to open for the container	--port=5000

Examples

apiVersion: batch.volcano.sh/v1alpha1
kind: Job
metadata:
  name: lm-mpi-job
spec:
  minAvailable: 1
  schedulerName: volcano
  plugins:
    mpi: ["--master=mpimaster","--worker=mpiworker","--port=22"]  ## MPI plugin register
  tasks:
    - replicas: 1
      name: mpimaster
      policies:
        - event: TaskCompleted
          action: CompleteJob
      template:
        spec:
          containers:
            - command:
                - /bin/sh
                - -c
                - |
                  mkdir -p /var/run/sshd; /usr/sbin/sshd;
                  mpiexec --allow-run-as-root --host ${MPI_HOST} -np 2 mpi_hello_world;
              image: volcanosh/example-mpi:0.0.3
              name: mpimaster
              workingDir: /home
          restartPolicy: OnFailure
    - replicas: 2
      name: mpiworker
      template:
        spec:
          containers:
            - command:
                - /bin/sh
                - -c
                - |
                  mkdir -p /var/run/sshd; /usr/sbin/sshd -D;
              image: volcanosh/example-mpi:0.0.3
              name: mpiworker
              workingDir: /home
          restartPolicy: OnFailure