User Guide

Learning about the NetWare Server 15
Server Operating System Administration Guide
103-000148-001
August 30, 2001
Novell Confidential
Manual 99a38 July 17, 2001
Figure 1 Mean Load, Threshold, and High and Low Trigger Loads
Without the margin provided by the threshold, threads would constantly move
from one processor to another, thereby compromising the productivity of the
system.
WARNING: Although the threshold is configurable, we strongly recommend that
you retain the preset optimum value. If after careful consideration, you decide to
modify the threshold, test it in an isolated system before modifying the value for a
production environment. If you modify the threshold, remember that you can
always reset it at the optimum value.
You can modify the threshold through NetWare Remote Manager. For details,
see “Setting the Load Balancing Threshold” on page 37.
Concurrency and Parallelism
NetWare has always had threads (typically referred to as processes) but until
NetWare 6 has not exploited the potential for parallelism in multithreaded
code. Multithreading enables multiple paths of parallel execution through the
code path. A software developer identifies tasks that can be performed
concurrently, that are not dependent on being performed in a fixed sequence,
and provides the mechanisms for assigning tasks to multiple threads and for
appropriate synchronization to protect data shared by the threads.
In a uniprocessor environment, multithreaded code allows threads to run
concurrently. This means that one or more threads are active on the same
processor. The threads appear to run at the same time—although they do not
actually do so. One thread, for example, can be blocking while another thread
I
ncreasing
Processor
Workload
Threshold
Mean
= value
High Trigger Load
(determined by Mean and Threshold)
Low Trigger Load
(determined by Mean and Threshold)