Sam Instances; Context Switches (Per Second) - NEC Express5800/320Ma User Manual

Chapter 4, "Sample Configuration"

SAM Instances

The SAM instances are described in the following sections.
Some values on the Express5800/320Ma Monitored Instances tab may be visible,
though grayed out, for the following reasons. The Scan retry, Scan idle, and Threshold
Setup settings are enabled by their associated check boxes. You must select the check
box before you can supply values for these parameters. If the check box is grayed out,
it means the setting is disabled by default. On the other hand, if you can check or clear
the check box, the default value will appear, regardless of whether or not the check box
is selected.

Context Switches (Per Second)

Context Switches (Per Second) is the rate of context switches from one thread to
another.
In a multitasking operating system, a context switch is the CPU's interruption of a
running thread to run another. The thread it starts running may belong to the same
process as the thread it interrupted, or to another. A context switch usually occurs
when:
•
A thread's time slice has expired.
•
A higher-priority thread that is ready to run preempts a lower-priority thread.
•
A running thread needs to wait for data or system resources before being able to
continue. A waiting thread relinquishes the remainder of its time slice.
Context switching gives a system the appearance of executing multiple threads
concurrently.
A high rate of context switches indicates that threads are sharing the processor. A low
rate indicates that threads are not sharing the processor very actively, perhaps
because a single application is monopolizing the processor, or perhaps because very
little processing is being done on the system. However, a high rate may indicate that
too many processes are running simultaneously. This, combined with other instances
such as CPU usage, may correlate to an overloaded system.
N O T E
If the Enable alerts for selected instance check box is
not checked, all parameter instances for the selected
instance are grayed out.
provides a full sample configuration.
Configuring the Software Availability Manager
SAM Instances
3-9