top shows '<swapped>'

[Oliver Fromme]

Thomas Hurst wrote:
 > 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,

You probably mean that the text pages of the binary
have not been paged into memory (that's different from
"swapping").  That's unlikely.

 > but this would imply there isn't a single page unique to each process.

I don't think that could happen.  As soon as you link
with libc (which sh, httpd and others certaily do), you
get a bunch of global variables and other things that
are not shared across processes.

 > 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?

That doesn't happen.  FreeBSD has a feature to proactively
swap processes that have been idle for a certain time, but
it's disabled by default, see: sysctl vm.swap_idle_enabled

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

I don't see it on any of my FreeBSD 6-stable machines, but
they run RELENG_6 of about 2 months ago.  Maybe a subtle
bug has been introduced recently.

Best regards
   Oliver

-- 
Oliver Fromme, secnetix GmbH & Co. KG, Marktplatz 29, 85567 Grafing b. M.
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