Tuning memory resources
system is a
Virtual memory is implemented using various physical
Depending on the system hardware, there may also be physical
on the CPU
chip itself (level-one (L1) cache),
or on the computer's motherboard (level-two (L2) cache),
and on peripheral hardware controller cards.
If recently accessed data (or, for some L1
and L2 caches, machine instructions) exists
in this memory, it can be accessed immediately rather
than having to retrieve it from more distant memory.
Physical memory as RAM chips; sometimes referred to as
primary, main, or core memory.
Program text (machine code instructions) as files within
filesystems on disk or
Swap space consisting of one or more disk divisions
or swap files within filesystems dedicated to this purpose.
The individual pieces of swap space are known as swap areas.
Swap space is also referred to as secondary memory.
Write-through caches store data
read from memory or a peripheral device;
they ensure that data is written synchronously
to memory or a physical device
before allowing the CPU to continue.
Write-back caches retain both read and written data
and do not require the CPU to synchronize
with data being written.
Most L2 caches work
with a limited amount of main memory.
Adding more RAM than the cache can handle may
actually make the machine slower.
For some machines with a 64KB L2 cache,
this only covers the first 16MB of physical memory.
See the documentation provided with your computer
or motherboard hardware for more details.
© 2003 Caldera International, Inc. All rights reserved.
SCO OpenServer Release 5.0.7 -- 11 February 2003