question about memory usage in linux

Gregory Hill Gregory_Hill at
Tue Nov 22 09:07:12 MST 2005

Does anyone know why top would report active memory usage far above that
used by the combination of all its processes?  Even listing in threaded
mode, the total of all processes memory usage adds up to several hundred
megabytes less than the 'active' memory usage listed in the summary.
It's a recent problem, but the memory and swap gets completely full,
requiring a full reboot to fix.  Killing mysql and apache (which are the
only things using anything above 1% of memory) still leaves several
hundred megabytes of 'active' memory usage.  I tried using ps, but it
doesn't show anything that wasn't listed by top.  Is there a better tool
to see what is using memory and what is not?  It's possible that some
mod_perl code has a memory leak, but usually the apache processes would
reflect that.  They don't.  I'm completely stumped.  Could it be failing
RAM?  Could someone have hacked the box and planted some super secret
program that doesn't show up in ps or top (or even replaced them with
alternate versions that don't show everything)?


It's running on Redhat 9, Apache 1.3/mod_perl/mod_php, mysql 4.1.  Yes,
I know it needs to be updated, but I can't take the server down.

Any ideas are welcome.



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