[CentOS] Why swap if there's still physical memory available

[Scott McClanahan]

> Also, the top values may not tell the whole story - RES should include 
> paged-in code plus memory allocated by the program.   VIRT includes code 
> not paged in yet and linked shared libraries, so the difference may not 
> all be in swap.
> 

I thought I remembered reading (maybe LKML) that RES also didn't account
for the COW efficiency of shared libraries.  Meaning RES could
potentially show a value which is larger than actual physical memory
used.  Sorry if I'm spreading misinformation :)

Thanks.