How to display processes using swap space

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 return 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 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 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 percantage 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!

Milosz Galazka's Picture

About Milosz Galazka

Milosz is a Linux Foundation Certified Engineer working for a successful Polish company as a system administrator and a long time supporter of Free Software Foundation and Debian operating system.

Gdansk, Poland https://sleeplessbeastie.eu