Orca Tips

The following are a list of scripts, functions and aliases that will make your life on Sharcnet much easier. Section 1.1, Things to consider, lists recommendations for courteous usage of Sharcnet resources. Section 1.2, A script to handle this for you, combines these ideas into a short script which makes job submission easy. Section 2, ~/.bashrc lists other useful commands for checking the sharcnet queue, connecting to the development nodes, or changing directories to a running job.

Submitting Jobs with Courteous and Efficient Usage

The following are recommendations for courteous usage and are not required, but are somewhat strongly recommend (especially the first two). If this is too much to remember, the code block below can be used to do all the work for you

Things to consider

1. If your simulation is using 16 processors or fewer, consider using the ppn flag
   • This flag specifies the number of processors per node, and helps to keep your jobs using whole nodes when available (avoids fragmenting jobs over more nodes than necessary)
   • Using no more than 16 processors means that your job can fit on a single node, which will reduce communication costs and provide a speed-up.
     • If you are using 8 processors, then use --ppn=8.
2. When submitting jobs, consider how much memory you will need.
   • The mpp flag specifies the memory per processor
   • If you are using whole nodes (--ppn=16), then you may as well use all of the memory (--mpp=4032M, for the low memory nodes, and --mpp=8064M, for the low memory nodes)
   • If you have not used the ppn flag, then try to only request as much memory as is needed. This will permit other jobs to run on the same node.
3. When submitting many jobs, consider linking them using the w flag
   • This flag instructs a job to wait until other jobs have finished.
     • Suppose you want to submit two large (processor wise) jobs. If the first job has a job id of 1234567 after it is submitted, then if the second job is submitted with -w 1234567, it will not run until the first job has finished.
     • While the first job is running, the second job will continue to build priority, so it will be more likely to start shortly after the first job finished (especially if the second job doesn't require more processors than the first).
       • NOTE: If the first job dies (runs out of time, memory, or has an internal error), the the second job will not run.
   • Note that this flag is only important when the queue is busy and your jobs would otherwise monopolize the available processors
     • As a rough guide, try to limit yourself to 128 processors at a time, although more can certainly be used when necessary.
   • The w flag can also be very useful during holidays/conferences/vacations to submit a series of jobs without blocking other users unnecessarily.

A script to handle this for you

All of this is done for you by using the following bash script (I suggest calling it submit.sh, and don't forget to make it executable: chmod +x submit.sh).

Copy this file into the directory and set the parameters for the given run in the Options section. Then submit the job by typing ./submit.sh.

The options available are:

• QUEUE - the queue the job will run in, there is no good reason not to use the kglamb queue
• NUM_PROCS - number of processors
• MPP - memory per processor
• RUNTIME - Run time of the job. Must be less than or equal to 7 days
• DELAY - whether to wait for another job to complete (true or false)
• DELAY_FOR - ID of job to complete before starting (not used if DELAY=false)
• NAME - name of job
• EXE_NAME - name of executable file

The ppn option is not in the script but can easily be added if desired. An analogous script for Matlab can be found at MATLAB on SHARCNET.

#!/bin/bash
# bash script for submitting a job to the sharcnet queue

#### Options ####
QUEUE=kglamb
NUM_PROCS=128
MPP=3.9g
RUNTIME=7d
DELAY=false
DELAY_FOR=9175185
NAME=grav_cur
EXE_NAME=grav_cur.x

#### OTHER INFO ####
DATE=`date +%Y-%m-%d_%H\h%M`
LOG_NAME="${DATE}.log"
ERR_NAME="${DATE}.err"

#### Submit ####
if [[ -x ${EXE_NAME} ]]; then
    if [[ "${DELAY}" = false ]]; then
        sqsub -q ${QUEUE} \
              -f mpi --nompirun \
              -n ${NUM_PROCS} \
              --mpp=${MPP} \
              -r ${RUNTIME} \
              -j ${NAME} \
              -o ${LOG_NAME} \
              -e ${ERR_NAME} \
              mpirun -mca mpi_leave_pinned 0 ${EXE_NAME}
    elif [[ "${DELAY}" = true ]]; then
        sqsub -q ${QUEUE} \
              -f mpi --nompirun \
              -n ${NUM_PROCS} \
              --mpp=${MPP} \
              -r ${RUNTIME} \
              -j ${NAME} \
              -o ${LOG_NAME} \
              -e ${ERR_NAME} \
              -w ${DELAY_FOR} \
              mpirun -mca mpi_leave_pinned 0 ${EXE_NAME}
    fi
    echo "Submitted ${EXE_NAME} with ${NUM_PROCS} processors"
    echo "          Requested memory:  ${MPP}"
    echo "          Requested runtime: ${RUNTIME}"
    echo "          Log file: ${LOG_NAME}"
else
    echo "Couldn't find ${EXE_NAME} - Try again."
fi

~/.bashrc

Copy the following lines of code into ~/.bashrc to make them available to you at the command line. Note: Thanks to Mike Dunphy and John Yawney for some of these.

Checking Job Status and Nodes Usage

• sqa gives a summary of all jobs submitted by the kglamb group
• sqmpi gives a summary of all mpi jobs
• sqh gives a node-by-node summary of the kglamb nodes
• sqm gives a summary of all of the jobs submitted by <userid>
  • You will want to replace <userid> with your userid when adding these to ~/.bashrc

alias sqa='showq -w class=kglamb'
alias sqmpi='showq -w class=mpi'
alias sqh='sqhosts orc361-392'
alias sqm='showq -w user=<userid>'

Accessing Development Nodes

The development notes provide an opportunity to run code directly, which can be very useful for development and testing. The following functions simplify the connection process.

• DevUsage provides a summary of how busy the nodes are (in terms of processor usage, each has 16 processors, so the lower the better)
• DevConnect automatically connects to the least used development node.

alias DevUsage="pdsh -w orc-dev[1-4] uptime | awk '{print \$1,\$NF}' | sort -n -k 2"

function DevConnect() {
    var=$(pdsh -w orc-dev[1-4] uptime | awk '{print $1,$NF}' | sort -n -k 2)
    var2=${var:0:8}
    printf "\n*** Accessing dev node: %s ***\n\n" $var2
    ssh -X $var2
}
export -f DevConnect

Moving to a Simulation/Job Directory

You may find that your directory tree becomes rather involved after a while, and so changing into a simulation directory / remembering the path can start to cumbersome. A useful function is cdJob, which takes you into the working directory for a submitted Sharcnet job, provided that you know the jobID.

function cdJob() {
   pth=$(sqjobs -l $1 | grep working | sed 's/^[^:]*: //g')
   echo "cd-ing to ${pth}"
   cd ${pth}
}
export -f cdJob

Usage is:

$ cdJob <jobID>