Linux Study Note 1

Redhat 3,4,5
with x86 architecture the first 16MB-896MB of physical memory is known as "low memory" (ZONE_NORMAL) which is permanently mapped into kernel space.
Many kernel resources must liven in the low memory zone.
In fact, many kernel operations can only take palce in this zone.
This means that the low memory area is the most performance critial zone.

Paging activity can be monitored using the vmstats command or using the sar command(option '-B') which comes with the sysstat RPM.