How to find out which processes are using swap spa

Question

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

Answer 1

I did notice this thread is rather old, but if you happen to stumble upon it, as I just did, another answer is: use smem.

Here is a link which tells you both how to install it and how to use it:

http://www.cyberciti.biz/faq/linux-which-process-is-using-swap/

Answer 2

It's not entirely clear if you mean you want to find the process who has most pages swapped out or process who caused most pages to be swapped out.

For the first you may run top and order by swap (press 'Op'), for the latter you can run vmstat and look for non-zero entries for 'so'.

Answer 3

I adapted a different script on the web to this long one-liner:

 { date;for f in /proc/[0-9]*/status; do 
   awk '{k[$1]=$2} END { if (k["VmSwap:"]) print k["Pid:"],k["Name:"],k["VmSwap:"];}' $f 2>/dev/null; 
   done | sort -n ; }

Which I then throw into a cronjob and redirect output to a logfile. The information here is the same as accumulating the Swap: entries in the smaps file, but if you want to be sure, you can use:

{ date;for m in /proc/*/smaps;do 
  awk '/^Swap/ {s+=$2} END { if (s) print FILENAME,s }' $m 2>/dev/null;
  done | tr -dc ' [0-9]\n' |sort -k 1n; }

The output of this version is in two columns: pid, swap amount. In the above version, the tr strips the non-numeric components. In both cases, the output is sorted numerically by pid.

Answer 4

Another script variant avoiding the loop in shell:

#!/bin/bash
grep VmSwap /proc/[0-9]*/status | awk -F':' -v sort="$1" '
  {
    split($1,pid,"/") # Split first field on /
    split($3,swp," ") # Split third field on space
    cmdlinefile = "/proc/"pid[3]"/cmdline" # Build the cmdline filepath
    getline pname[pid[3]] < cmdlinefile # Get the command line from pid
    swap[pid[3]] = sprintf("%6i %s",swp[1],swp[2]) # Store the swap used (with unit to avoid rebuilding at print)
    sum+=swp[1] # Sum the swap
  }
  END {
    OFS="\t" # Change the output separator to tabulation
    print "Pid","Swap used","Command line" # Print header
    if(sort) {
      getline max_pid < "/proc/sys/kernel/pid_max"
      for(p=1;p<=max_pid;p++) {
        if(p in pname) print p,swap[p],pname[p] # print the values
      }
    } else {
      for(p in pname) { # Loop over all pids found
        print p,swap[p],pname[p] # print the values
      }
    }
    print "Total swap used:",sum # print the sum
  }'

Standard usage is script.sh to get the usage per program with random order (down to how awk stores its hashes) or script.sh 1 to sort the output by pid.

I hope I've commented the code enough to tell what it does.

Answer 5

I don't know of any direct answer as how to find exactly what process is using the swap space, however, this link may be helpful. Another good one is over here

Also, use a good tool like htop to see which processes are using a lot of memory and how much swap overall is being used.

Answer 6

On MacOSX, you run top command as well but need to type "o" then "vsize" then ENTER.