Provided by: pcp_3.5.11_i386
pmns - the performance metrics name space
When using the Performance Metrics Programming Interface (PMAPI) of the
Performance Co-Pilot (PCP), performance metrics are identified by an
external name in a hierarchic Performance Metrics Name Space (PMNS),
and an internal identifier, the Performance Metric Identifier (PMID).
A PMNS specifies the association between a metric's name and its PMID.
A PMNS is defined on one or more ASCII source files, that may be
compiled using pmnscomp(1) to produce a binary PMNS. Note that
pmnscomp(1) is normally invoked from the $PCP_VAR_DIR/pmns/Rebuild
script if necessary when pmcd(1) is started.
Loading of a PMNS is done by calling pmLoadNameSpace(3) which silently
tolerates either the ASCII or binary formats. Alternatively,
pmLoadASCIINameSpace(3) may be used to load just the ASCII format.
If the binary format is used, no checking is performed for aliasing in
which multiple names in the PMNS are associated with a single PMID. If
the ASCII format is to be used, duplicate PMIDs are not allowed,
although pmLoadASCIINameSpace(3) provides an alternative interface with
user-defined control over the processing of duplicate PMIDs in an ASCII
format PMNS. The external ASCII format for a PMNS conforms to the
syntax and semantics described in the following sections.
There is one default PMNS in the files below $PCP_VAR_DIR/pmns,
although users and application developers are free to create and use
alternate PMNS's. For an example of this, see the PCP Tutorial in
Although an application can call pmLoadNameSpace(3), normally this is
only done directly for the -n command line option where an explicit
root PMNS file is specified. Since PCP version 2 uses a distributed
PMNS (see below), an application can extract PMNS information from a
host's PMCD or an archive. If the PMNS source (pmcd or archive) is
version 1 (see PCPIntro(1)), however, then the local PMNS will be
loaded using the path specified by the environment variable
In PCP version 1, the PMNS functions in the API all operated on a PMNS
loaded locally from a file. Since PCP version 2, however, PMNS
functions may get the PMNS information remotely from a PMCD or directly
from the meta data of an archive. We call this a distributed PMNS. It
has the advantage that the PMNS should always match the source of the
metrics. For example, in PCP version 1, if one wanted to access a
remote PMCD which had an agent installed which one didn't have
installed locally, then the local PMNS had to be updated just for that
agent. This is no longer the case.
In order to be compatible with version 1 PMCDs and version 1 archives
(see PCPIntro(1)), the local PMNS (PMNS_DEFAULT) is automatically
loaded as was done previously in PCP version 1.
From an API level, there has been minimal changes. The main change is
that if an application wants to use the distributed PMNS then it should
not call pmLoadNameSpace(3) or pmLoadASCIINameSpace(3). Doing so will
load the local PMNS as specified above. Not calling these functions
would previously (in PCP version 1) cause an error when trying to
access the PMNS but now (in PCP version 2) it will force the PMNS
functions to look at the metrics source for their information.
The PMNS specification is initially passed through pmcpp(1). This
means the following facilities may be used in the specification
+ C-style comments
+ #include directives
+ #define directives and macro substitution
+ conditional processing via #ifdef ... #endif, etc.
When pmcpp(1) is executed, the ``standard'' include directories are the
current directory and $PCP_VAR_DIR/pmns.
The general syntax for a non-leaf node in the PMNS is as follows
Where pathname is the full pathname from the root of the PMNS to this
non-leaf node, with each component in the pathname separated by a
``.''. The root node for the PMNS must have the special name ``root'',
but the common prefix ``root.'' must be omitted from all pathnames.
Each component in the pathname must begin with an alphabetic character,
and be followed by zero or more characters drawn from the alphabetics,
the digits and the underscore ``_'') character. For alphabetic
characters in a pathname component, upper and lower case are
Non-leaf nodes in the PMNS may be defined in any order.
The descendent nodes are defined by the set of names, relative to the
pathname of their parent non-leaf node. For the descendent nodes, leaf
nodes have a pmid specification, non-leaf nodes do not. The syntax for
the pmid specification has been chosen to help manage the allocation of
PMIDs across disjoint and autonomous domains of administration and
implementation. Each pmid consists of 3 integer parts, separated by
colons, e.g. 14:27:11. This hierarchic numbering scheme is intended to
mirror the implementation hierarchy of performance metric domain,
metrics cluster (data structure or operational similarity) and
individual metric. In practice, the two leading components are likely
to be macros in the PMNS specification source, and pmcpp(1) will
convert the macros to integers. These macros for the initial
components of the pmid are likely to be defined either in a standard
include file, e.g. $PCP_VAR_DIR/pmns/stdpmid, or in the current source
To support dynamic metrics, where the existence of a metric is known to
a PMDA, but not visible in the PMNS, a variant syntax for the pmid is
supported, namely a domain number followed by asterisks for the other
components of the pmid, e.g. 14:*:*. The corresponding metric name
forms the root of a subtree of dynamic metric names defined in the
corresponding PMDA as identified by the domain number.
The current allocation of the high-order (PMD or domain) component of
PMIDs is as follows.
│ Range │ Allocation │
│ 0 │ reserved │
│ 1-31 │ PMDAs from the PCP base product and/or IRIX │
│ 32-39 │ Oracle │
│ 40-47 │ Sybase │
│ 48-55 │ Informix │
│ 56-58 │ SNMP Gateway PMDA │
│ 59-63 │ Linux PMDAs │
│ 64-69 │ ISV PMDAs │
│ 70-128 │ more PMDAs from the PCP base product and/or IRIX │
│129-510 │ End-user PMDAs and demo PMDAs │
│ 511 │ RESERVED │
#define IRIX 1
#define FOO 317
#define NETWORK 26
#define CPU 10
#define USER 20
#define KERNEL 21
#define IDLE 22
PCPIntro(1), pmcd(1), pmcpp(1), pmnscomp(1), PCPIntro(3), PMAPI(3),
pmErrStr(3), pmGetConfig(3), pmLoadASCIINameSpace(3),
pmLoadNameSpace(3), pcp.conf(4) and pcp.env(4).