There are three forms of the metricspec. First, on the command
line a metricspec can start with a colon (``:'') to indicate a
reference to a metricset to be read from the pmrep configuration
file. Second, the compact form of a metricspec is a one-line
metric specification which can be used both on the command line
and in the [global] and custom sections of the configuration
file. The only difference of its usage in the configuration file
is that the metric name is used as the key and the optional
specifiers as values. The compact form of the metricspec is
specified in detail in pmrep(1). The third, verbose form of a
metricspec, is valid only in the configuration file (see below).
A key containing a dot (``.'') is interpreted as a metric name
(see above), a non-option key not containing a dot is interpreted
as an identifier (see below).
The verbose form of a metricspec starts with a declaration
consisting of a mandatory identifier as the key and the actual
performance metric name (a PMNS leaf node) as its value. This
equals to the compact form of the metricspec defining the same
performance metric without any of optional specifiers defined.
The identifier is arbitrary and is not used otherwise except for
binding the below specifiers and the metric together.
The following specifiers are optional in the verbose form and can
be used as keys in any order with an earlier declared identifier
followed by a dot and the specifier (as in identifier.specifier):
label
Defines text label for the metric used by supporting
output targets.
formula
Defines the needed arithmetic expression for the metric.
For details, see pmRegisterDerived(3).
instances
Defines the instances to be reported for the metric.
For details, see pmrep(1).
unit
Defines the unit/scale conversion for the metric. Needs
to be dimension-compatible and is used with non-string
metrics. For allowed values, see pmrep(1).
type
If set to raw rate conversion for the metric will be
disabled.
width
Defines the width of the output column for the metric.
precision
Defines precision for numeric non-integer output values.
limit
Defines value limit filter for numeric metric values.
