most recent FC3 kernel memory usage(?)

[Anne & Lynn Wheeler]

I seem to be seeing some different memory statistics in most recent FC3 
kernel:
kernel-smp-2.6.11-1.14_FC3

i've got a 4gbyte machine that linux has always claimed is 3.5gbytes (at 
least gnome-system-monitor reports it as such). in early fedora kernels 
i would get up to maybe 600-800mbytes memory used and possibly tens of 
mbytes of swap useage.

latest kernel will see over gbyte nominal memory useage and only drops 
back to 400-500mbytes when i kill my big applications. even logging 
off/on doesn't drop it down. I have to reboot and then log on to see it 
down to 150mbytes of used memory. in the past, log off/on would be 
sufficient to drop memory used numbers ... w/o having to reboot ... and 
usually just restarting mozilla will do the trick .... some mozilla
postings about using 400mbytes of memory (and mozilla starting to slow 
down) when hitting 250 active tabs:
http://www.garlic.com/~lynn/2005e.html#48
http://www.garlic.com/~lynn/2005e.html#49

this might be a storage cancer ... or is it possible that it is a change 
in 2.6.11 on how it handles virtual memory and/or possibly file caching????

i saw a marginally related characteristic when upgrading another machine 
from FC3 to FC4. FC3 hadn't labeled the swap volumes ... FC4 updated 
/etc/fstab with some default swap volume label names (w/o actually 
writing out any labels). As a result, when the machine first came up ... 
it didn't automatically mount the swap volumes. As a result ... used 
memory appeared to be 100-200 mbytes more than i was expecting. I 
eventually noticed that swap hadn't been mounted. I manually mounted 
swap and then updated /etc/fstab so that swap was back to the FC3 
specification (rather than the FC4 "label" specification).