I have an ubuntu vps running that has about 300MB of memory, of which only 20% or less is free right now ...
My question is, how can I figure out what particular program I'm running that is causing it to swap so much?

4 Answers 4


To find out the amount of swap space used by every process, run top (not htop), press 'f' to select columns (f for fields) to display, press 'p' to add swap to display, press 'o' to sort the table (o for order by) and press 'p' again to order by swap usage.

  • That was exactly what i needed ... If only i could figure out how to accomplish this in htop. Apr 14, 2010 at 7:48
  • Also, to sort I had to use shift+o and shift+p Apr 14, 2010 at 7:54
  • 1
    In htop, you use the "F" Keys to sort. See the line at the very bottom of the screen. Apr 15, 2010 at 7:09
  • 1
    The SWAP column and thus this answer is mesleading. For an explanation see hisham.hm/htop/index.php?page=faq Nov 19, 2017 at 15:42
  • 1
    This seems to be out of date. p has no effect, step-by-step instructions that worked 20 Sept 2021 shown here Sep 20, 2021 at 18:02

start with running


and pressing M [ shift+m ].

you will get process list sorted by mem consumption.

  • was already using htop. Apr 14, 2010 at 0:37

smem is a bit harder to use than top, but offers good information. You could start with with sudo smem -s uss -r -k which will output:

  PID User     Command                         Swap      USS      PSS      RSS 
12345 spam     /usr/lib/jvm/java-6-sun/bin        0   620.9M        0   626.5M 
98765 eggs     /usr/bin/java -Xmx1500m -XX        0   544.2M        0   549.9M 

You might also want to check out this lwn.net article, which explains the difference between RSS, PSS and USS.


Another option is htop, which has better output in some cases.

  • I'm already using htop ... can't figure out how to see the amount of swap each process is using. Apr 14, 2010 at 0:36
  • 2
    @user37899 You should at least check that it works, if you don't say exactly how, before suggesting a solution Apr 14, 2010 at 8:17

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