top shows '<swapped>'

Thomas Hurst tom.hurst at
Wed May 9 16:47:29 UTC 2007

* Bill LeFebvre (bill at wrote:

>  The <> are only used when the process flag PS_INMEM is clear, which
>  is supposed to indicate that the process is or is not "in memory".
>  This flag is only ever cleared in swapout, called from swapout_procs.
>  My bet is that the processes are being marked for swap but the dirty
>  pages never actually go anywhere since you don't have a backing
>  store.  Maybe someone more familiar with the inner workings of the VM
>  system can fill us in on what happens on a system with no swap.

I'm seeing this sort of thing too -- I do have swap, but it's not being
used by these processes (swapoff -a didn't do anything to them):

 Mem: 1672M Active, 5337M Inact, 279M Wired, 400M Cache, 215M Buf, 74M Free
 Swap: 10G Total, 12K Used, 10G Free

 1251 www           1   4    0 87884K     0K accept 2   0:00  0.00% <httpd>
 1106 root          1  20    0 12756K     0K pause  1   0:00  0.00% <smbd>
 950  root          1 115    0  8536K     0K select 3   0:00  0.00% <pure-ftpd>
 1143 mysql         1   8    0  5220K     0K wait   3   0:00  0.00% <sh>
 1288 root          1   5    0  3644K     0K ttyin  2   0:00  0.00% <getty>

The bulk of the data is probably "swapped" to the on-disk binaries, but
this would imply there isn't a single page unique to each process.
Quite why it's bothering in the first place with >5GB Inact I'm not
sure -- is it unmapping idle processes to conserve VM objects?

I also find it interesting that I only noticed this behavior a few days
ago and suddenly someone else mentions it too :)

Thomas 'Freaky' Hurst

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