How to find out which processes are using swap space in Linux?

Question

Under Linux, how do I find out which process is using the swap space more?

Answer 1

You can use Procpath (author here), to simplify parsing of VmSwap from /proc/$PID/status.

$ procpath record -f stat,cmdline,status -r 1 -d db.sqlite
$ sqlite3 -column db.sqlite \
  'SELECT status_name, status_vmswap FROM record ORDER BY status_vmswap DESC LIMIT 5'
Web Content  192136       
okular       186872       
thunderbird  183692       
Web Content  143404       
MainThread   86300

You can also plot VmSwap of processes of interest over time like this. Here I'm recording my Firefox process tree while opening a couple tens of tabs along with statrting a memory-hungry application to try to cause it to swap (which wasn't convincing for Firefox, but your kilometrage may vary).

$ procpath record -f stat,cmdline,status -i 1 -d db2.sqlite \
  '$..children[?(@.stat.pid == 6029)]'
# interrupt by Ctrl+C
$ procpath plot -d db2.sqlite -q cpu --custom-value-expr status_vmswap \
  --title "CPU usage, % vs Swap, kB"