Log and graph peformance metrics on a single process

process_graph.sh

#!/bin/bash

# Log and graph peformance metrics on a single process
# Based on: http://brunogirin.blogspot.com.au/2010/09/memory-usage-graphs-with-ps-and-gnuplot.html
#
# Requires gnuplot to be installed and on your path.
#
# Run: ./process_graph [process name] [pid]

DEFAULT_PROCNAME="Xorg"

PROCNAME=${1:-$DEFAULT_PROCNAME}
PID=${2:-`pidof $PROCNAME`}
NUMCPU=$(cat /proc/cpuinfo | grep processor | wc -l)
TIMEOUT=1
NUMTIMES=60

if [ -z $PID ]; then
    echo "PID for $PROCNAME not found, try manually specifying it"
    exit
fi
echo "Watching the $PROCNAME [$PID] process for $[TIMEOUT*NUMTIMES] seconds..."

# Calculate the total %CPU usage over the period since
# the function was last called.
previdle=0
prevtotal=0
TOTALCPU=0
DIFF=0
calcTotalCpu() {
    # Read the current cpu values from the stat file
    read cpu user nice sys curidle rest < /proc/stat
    curtotal=$[user+nice+sys+curidle]

    # If this isn't the first time this function has been called,
    # calculate the total %CPU since the previous time
    if [ "$prevtotal" -ne "0" ]; then
        DIFF=$[curtotal-prevtotal]
        TOTALCPU=$(echo "scale=2; 100*(($curtotal-$prevtotal) - ($curidle-$previdle)) / ($curtotal-$prevtotal)" | bc)
    fi

    # Store the current idle and total times for the next time
    previdle=$curidle
    prevtotal=$curtotal
}

# Calculate the total %CPU usage for a PID over the period since
# the function was last called.
prevpidtotal=0
PIDCPU=0
calcPidCpu() {
    # Read the current PID cpu values from the stat file
    curpidtotal=`cat /proc/${PID}/stat | awk '{t = $14 + $15; print t}'`

    # Calculate the PID's CPU usage
    if [ "$DIFF" -ne 0 ]; then
        PIDCPU=$(echo "scale=2; ($NUMCPU * ($curpidtotal-$prevpidtotal) * 100) / $DIFF" | bc)
    fi

    # Store the current PID total for the next time
    prevpidtotal=$curpidtotal
}

#
# Main script
#

# Remove old log
rm -rf ${PROCNAME}_perf.log

# Loop for the user defined duration/period and log metrics
for i in `seq 1 $NUMTIMES`; do
    # Calculate CPU usage
    calcTotalCpu
    calcPidCpu

    # Get memory usage
    PIDMEM=`ps -p $PID -o %mem=`

    # If all values were calculated, output to log file
    if [ $(echo "$PIDCPU != 0" | bc -l) == 1 ]; then
        echo "${PIDCPU}${PIDMEM}" >> ${PROCNAME}_perf.log
    fi

    sleep $TIMEOUT
done

# Use gnuplot to convert the log file to a graph
echo "Plotting graph to ${PROCNAME}_graph.png"
gnuplot <<- EOF
    set term png small size 800,600
    set output "${PROCNAME}_graph.png"
    set title "${PROCNAME} Performance"
    set xlabel "Time (sec)"
    set ylabel "%CPU" textcolor rgb "red"
    set y2label "%MEM" textcolor rgb "green"
    set ytics nomirror textcolor rgb "red"
    set y2tics nomirror in textcolor rgb "green"
    set yrange [0:*]
    set y2range [0:*]
    plot "${PROCNAME}_perf.log" using 1 with lines linewidth 3 axes x1y1 title "%CPU", \
        "${PROCNAME}_perf.log" using 2 with lines linewidth 3 axes x1y2 title "%MEM"
EOF