How does HP Diagnostics calculate the MemoryUsage and VirtualMemoryUsage system metrics

The system metrics for measuring server memory usage in HP Diagnostics probes on Windows platforms as specified in the "metrics.config" configuration file are:

system/MemoryUsage = MemoryUsage|percent|System

system/VirtualMemoryUsage = VirtualMemoryUsage|percent|System

While there are some dependencies on the particular platform and operating system where the probe is installed the rule of thumb is that this information is sourced from the operating system using the built-in operating system performance measurement mechanisms. Some calculations may be performed for percentages but the majority of metric information is collected and passed through unchanged, for example counts.

The "MemoryUsage" for a Windows platform is calculated using the "Working Set" counter for process objects. Similarly the "VirtualMemoryUsage" for a Windows platform is calculated using the "Private Bytes" counter for process objects. Both data items are source from "perfmon" on the Windows platform.

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