I found this useful shell script on a website a while back; works perfectly:
#!/bin/bash
# Get current swap usage for all running processes
# Erik Ljungstrom 27/05/2011
# Modified by Mikko Rantalainen 2012-08-09
# Pipe the output to "sort -nk3" to get sorted output
SUM=0
OVERALL=0
for DIR in `find /proc/ -maxdepth 1 -type d -regex "^/proc/[0-9]+"`
do
PID=`echo $DIR | cut -d / -f 3`
PROGNAME=`ps -p $PID -o comm --no-headers`
for SWAP in `grep Swap $DIR/smaps 2>/dev/null | awk '{ print $2 }'`
do
let SUM=$SUM+$SWAP
done
if (( $SUM > 0 )); then
echo "PID=$PID swapped $SUM KB ($PROGNAME)"
fi
let OVERALL=$OVERALL+$SUM
SUM=0
done
echo "Overall swap used: $OVERALL KB"
The output will look like this:
PID=1 swapped 100 KB (init) PID=479 swapped 652 KB (udevd) PID=816 swapped 408 KB (udevd) PID=1152 swapped 380 KB (vmtoolsd) PID=1247 swapped 92 KB (portreserve) PID=1254 swapped 292 KB (rsyslogd) PID=1887 swapped 132 KB (xinetd) PID=1926 swapped 264 KB (crond) PID=2039 swapped 72 KB (mingetty) PID=2041 swapped 76 KB (mingetty) PID=2043 swapped 648 KB (udevd) PID=2044 swapped 76 KB (mingetty) PID=2046 swapped 72 KB (mingetty) PID=2048 swapped 76 KB (mingetty) PID=2050 swapped 72 KB (mingetty) PID=2625 swapped 16116 KB (httpd) PID=3086 swapped 5596 KB (named) PID=3569 swapped 104 KB (couriertcpd) PID=3571 swapped 28 KB (courierlogger) PID=3579 swapped 96 KB (couriertcpd) PID=3581 swapped 32 KB (courierlogger) PID=3587 swapped 88 KB (couriertcpd) PID=3589 swapped 16 KB (courierlogger) PID=3596 swapped 88 KB (couriertcpd) PID=3598 swapped 28 KB (courierlogger) PID=3782 swapped 16108 KB (httpd) PID=7994 swapped 16108 KB (httpd) PID=9076 swapped 192 KB (mysqld_safe) PID=9205 swapped 300 KB (mysqld) PID=9719 swapped 16108 KB (httpd) PID=9723 swapped 16108 KB (httpd) PID=10019 swapped 16108 KB (httpd) PID=10021 swapped 16108 KB (httpd) PID=11713 swapped 16108 KB (httpd) PID=11935 swapped 16108 KB (httpd) PID=11938 swapped 16108 KB (httpd) PID=11943 swapped 16108 KB (httpd) PID=12101 swapped 16108 KB (httpd) PID=12435 swapped 456 KB (master) PID=12447 swapped 328 KB (qmgr) PID=12698 swapped 416 KB (tlsmgr) PID=12803 swapped 16108 KB (httpd) PID=12818 swapped 16108 KB (httpd) PID=12822 swapped 16108 KB (httpd) PID=12824 swapped 16108 KB (httpd) PID=13757 swapped 16108 KB (httpd) PID=14248 swapped 16108 KB (httpd) PID=14251 swapped 16108 KB (httpd) PID=14252 swapped 16108 KB (httpd) PID=14254 swapped 16108 KB (httpd) PID=14255 swapped 16108 KB (httpd) PID=14256 swapped 16108 KB (httpd) PID=14257 swapped 16108 KB (httpd) PID=17372 swapped 536 KB (sshd) Overall swap used: 400712 KB