Identify and print processes using swap space to get a better understanding of the Linux operating system.
Display processes using swap space
Use the following command to simply display processes using swap space. This list will be sorted by process id by default due to a way find command returns its results, which are parsed by awk utility.
$ find /proc -maxdepth 2 -path "/proc/[0-9]*/status" -readable -exec awk -v FS=":" '{process[$1]=$2;sub(/^[ \t]+/,"",process[$1]);} END {if(process["VmSwap"] && process["VmSwap"] != "0 kB") printf "%10s %-30s %20s\n",process["Pid"],process["Name"],process["VmSwap"]}' '{}' \;
[..]
11224 bash 520 kB
11372 chrome 4124 kB
11997 python2 1376 kB
14831 chrome 4296 kB
20457 chrome 4580 kB
20463 cat 92 kB
20464 cat 92 kB
20467 chrome 5204 kB
20468 nacl_helper 420 kB
20471 chrome 5100 kB
20587 chrome 12212 kB
20629 chrome 8224 kB
[..]
Display processes using swap space sorted by used space
Use additional awk instance to add a temporary column at the beginning, so data could be easily sorted by used swap space in ascending order.
$ find /proc -maxdepth 2 -path "/proc/[0-9]*/status" -readable -exec awk -v FS=":" '{process[$1]=$2;sub(/^[ \t]+/,"",process[$1]);} END {if(process["VmSwap"] && process["VmSwap"] != "0 kB") printf "%10s %-30s %20s\n",process["Pid"],process["Name"],process["VmSwap"]}' '{}' \; | awk '{print $(NF-1),$0}' | sort -h | cut -d " " -f2-
[..]
20587 chrome 12212 kB
2098 firefox 12588 kB
2080 applet.py 13072 kB
10801 Web Content 15796 kB
21412 atom 17384 kB
1629 cinnamon 18584 kB
1300 Xorg 22048 kB
28740 atom 22692 kB
21482 atom 32800 kB
28761 atom 51644 kB
21444 atom 68044 kB
21432 atom 77080 kB
Display top ten processes using swap space
The following command will sort processes by used swap space in descending order, then execute head utility to limit the number of records.
$ find /proc -maxdepth 2 -path "/proc/[0-9]*/status" -readable -exec awk -v FS=":" '{process[$1]=$2;sub(/^[ \t]+/,"",process[$1]);} END {if(process["VmSwap"] && process["VmSwap"] != "0 kB") printf "%10s %-30s %20s\n",process["Pid"],process["Name"],process["VmSwap"]}' '{}' \; | awk '{print $(NF-1),$0}' | sort -hr | head | cut -d " " -f2-
21432 atom 77080 kB
21444 atom 67596 kB
28761 atom 51644 kB
21482 atom 32800 kB
28740 atom 22692 kB
1300 Xorg 22048 kB
1629 cinnamon 18584 kB
21412 atom 17384 kB
10801 Web Content 15796 kB
2080 applet.py 13072 kB
Display top ten processes using swap space with percentage values
Read (see 1st command) or calculate (see 2nd command) total available swap space to calculate and display per-process percentage swap usage. Both of these commands are equivalent.
$ find /proc -maxdepth 2 -path "/proc/[0-9]*/status" -readable -exec awk -v FS=":" -v TOTSWP="$(cat /proc/meminfo | sed -n -e "s/^SwapTotal:[ ]*\([0-9]*\) kB/\1/p")" '{process[$1]=$2;sub(/^[ \t]+/,"",process[$1]);} END {if(process["VmSwap"] && process["VmSwap"] != "0 kB") {used_swap=process["VmSwap"];sub(/[ a-zA-Z]+/,"",used_swap);percent=(used_swap/TOTSWP*100); printf "%10s %-30s %20s %6.2f%\n",process["Pid"],process["Name"],process["VmSwap"],percent} }' '{}' \; | awk '{print $(NF-2),$0}' | sort -hr | head | cut -d " " -f2-
$ find /proc -maxdepth 2 -path "/proc/[0-9]*/status" -readable -exec awk -v FS=":" -v TOTSWP="$(cat /proc/swaps | sed 1d | awk 'BEGIN{sum=0} {sum=sum+$(NF-2)} END{print sum}')" '{process[$1]=$2;sub(/^[ \t]+/,"",process[$1]);} END {if(process["VmSwap"] && process["VmSwap"] != "0 kB") {used_swap=process["VmSwap"];sub(/[ a-zA-Z]+/,"",used_swap);percent=(used_swap/TOTSWP*100); printf "%10s %-30s %20s %6.2f%\n",process["Pid"],process["Name"],process["VmSwap"],percent} }' '{}' \; | awk '{print $(NF-2),$0}' | sort -hr | head | cut -d " " -f2-
21432 atom 77080 kB 0.93%
21444 atom 67596 kB 0.82%
28761 atom 51644 kB 0.62%
21482 atom 32800 kB 0.40%
28740 atom 22692 kB 0.27%
1300 Xorg 22048 kB 0.27%
1629 cinnamon 18584 kB 0.22%
21412 atom 17384 kB 0.21%
10801 Web Content 15796 kB 0.19%
2080 applet.py 13072 kB 0.16%
You can extend this idea further by creating bar charts in terminal. awk is beautiful!