What determines performance
A computer system consists of a finite set
of hardware and software components.
These components constitute the
of the system.
One of the tasks of the operating system is
to share these resources between the programs that are
running on the system.
Performance is a measure of how well the operating system does this
task; the aim of performance tuning is to make it do this task better.
A system's hardware resources have inherent physical limits
in the quantity of data they can handle
and the speed with which they can do this.
The physical subsystems that compose hardware include:
Operating system resources are limited by the hardware resources
such as the amount of memory available and how it is accessed.
The internal resources of the operating system
are usually configurable
and control such things as the size of data structures,
security policy, standards conformance, and hardware modes.
One or more central processing units (CPUs),
and the ancillary processors that support them.
Memory -- both in Random Access Memory (RAM)
devices including hard and floppy disk drives,
tape drives, serial ports, and network cards.
Networks -- both Local Area Networks
(LANs) and Wide Area Networks (WANs).
Examples of operating system resources are:
If your system is connected to one or more networks,
it may depend on remote machines to serve files,
perform database transactions, perform calculations,
run X clients, and provide swap space,
or it may itself provide some of these services.
Your system may be a router or gateway
if it is connected to more than one network.
In such cases, the performance of the network
and the remote machines will have a direct influence
on the performance of your system.
The tables that the operating system uses
to keep track of users and the programs they are running.
The buffer cache and other memory buffers
that reduce dependence on accessing slow peripheral devices.
Hardware factors that influence performance
© 2003 Caldera International, Inc. All rights reserved.
SCO OpenServer Release 5.0.7 -- 11 February 2003