Owner's Manual

Monitoring and Alerting 99
Outgoing Packets/Sec The rate at which packets are sent on the network
interface.
Physical Disk
Average Access Time The time, in seconds, of the average disk transfer.
Physical Disk IO/Sec The rate of read and write operations on the disk.
System
Context Switches/Sec The combined rate at which all processors on the
computer are switched from one thread to another.
Context switches occur when a running thread
voluntarily relinquishes the processor, is preempted
by a higher priority ready thread, or switches
between user-mode and privileged (kernel) mode to
use an Executive or subsystem service. It is the sum
of Thread\\Context Switches/sec for all threads
running on all processors in the computer and is
measured in numbers of switches. There are
context switch counters on the System and Thread
objects. This counter displays the difference
between the values observed in the last two
samples, divided by the duration of the sample
interval.
Processor Queue Length The number of threads in the processor queue.
Unlike the disk counters, this counter shows ready
threads only, not threads that are running. There is
a single queue for processor time even on
computers with multiple processors. Therefore, if a
computer has multiple processors, you need to
divide this value by the number of processors
servicing the workload. A sustained processor
queue of less than 10 threads per processor is
normally acceptable, dependent of the workload.
NOTE: These definitions are for performance monitoring counters for Windows; the
definitions for Linux may vary slightly.
Table 9-4. Metrics for Performance
(continued)
Metric
(Total Count=simple+compound)
Description
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