The `perfmon` metricset of the Windows module reads Windows performance
counters.

[float]
=== Configuration

You must configure queries for the Windows performance counters that you wish
to collect. The example below collects processor time and disk writes every
10 seconds. If either of the counters do not exist it will ignore the error.

[source,yaml]
----
- module: windows
  metricsets: [perfmon]
  period: 10s
  perfmon.ignore_non_existent_counters: true
  perfmon.counters:
    - instance_label: processor.name
      instance_name: total
      measurement_label: processor.time.total.pct
      query: '\Processor Information(_Total)\% Processor Time'

    - instance_label: physical_disk.name
      measurement_label: physical_disk.write.per_sec
      query: '\PhysicalDisk(*)\Disk Writes/sec'

    - instance_label: physical_disk.name
      measurement_label: physical_disk.write.time.pct
      query: '\PhysicalDisk(*)\% Disk Write Time'
----

*`ignore_non_existent_counters`*:: A boolean option that causes the
metricset to ignore errors caused by counters that do not exist when set to
true. Instead of an error, a message will be logged at the info level stating
that the counter does not exist.

*`counters`*:: Counters specifies a list of queries to perform. Each individual
counter requires three config options - `instance_label`, `measurement_label`,
and `query`.

[float]
==== Counter Configuration

Each item in the `counters` list specifies a perfmon query to perform. In the
events generated by the metricset these configuration options map to the field
values as shown below.

----
"%[instance_label]": "%[instance_name] or <perfmon_counter_name>",
"%[measurement_label]": <perfmon_counter_value>,
----

*`instance_label`*:: The label used to identify the counter instance. This
field is required.

*`instance_name`*:: The instance name to use in the event when the counter's
path (`query`) does not include an instance or when you want to override the
instance name. For example with `\Processor Information(_Total)` the
instance name would be `_Total` and by setting `instance_name: total` you can
override the value.
+
The setting has no effect with wildcard queries (e.g.
`\PhysicalDisk(*)\Disk Writes/sec`).

*`measurement_label`*:: The label used for the value returned by the query.
This field is required.

*`query`*:: The perfmon query. This is the counter path specified in
Performance Data Helper (PDH) syntax. This field is required. For example
`\Processor Information(_Total)\% Processor Time`. An asterisk can be used in
place of an instance name to perform a wildcard query that generates an event
for each counter instance (e.g. `\PhysicalDisk(*)\Disk Writes/sec`).

*`format`*:: Format of the measurement value. The value can be either `float` or
`long`. The default is `float`.

