Taken from the following link:

http://www.rigreen.freeserve.co.uk/o...em_on_unix.doc

'vmstat'
--------
The 'vmstat' utility is used to print out system-wide information on
the performance of the paging subsystem. Its major limitation is that
it does not print out per-process information. The format of 'vmstat'
output varies between UNIX ports: the key fields to look at are the
ones that measure the number of page-in and page-out events per
second. Remember that some paging activity is normal, so you will have
to decide for yourself what number of pages-in or pages-out per second
means that your page pool is too small.

'sar'
-----
On SYSV-based systems, the 'sar' utility is used to print out
system-wide information on the performance of a wide variety of kernel
subsystems. Like 'vmstat', its major limitation is that it does not
print out per-process information. The '-r', '-g', and '-p' options
are the most useful for examining the behavior of the paging subsystem.