Ubuntu Manpage: PMNS - the performance metrics name space

NAME

       PMNS - the performance metrics name space

SYNOPSIS

       $PCP_VAR_DIR/pmns

DESCRIPTION

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.

Loading of a PMNS is done by calling pmLoadNameSpace(3) or pmLoadASCIINameSpace(3).

As of Version 3.10.3 of PCP, by default duplicate names for the same PMID are allowed in
the PMNS, although pmLoadASCIINameSpace(3) provides an alternative interface with user-
defined control over the processing of duplicate names in the PMNS. The external 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 $PCP_DEMOS_DIR/Tutorial.

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 is a version 1 archive (see
PCPIntro(1)), however, then the local PMNS will be loaded using the path specified by the
environment variable PMNS_DEFAULT.

DISTRIBUTED PMNS

       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.

PROCESSING FRAMEWORK

       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 pre-processing with pmcpp(1) may be omitted in some cases where the PMNS is  known  to
       not  contain  any  C-style  comments,  preprocessor  directives  or  macros.  Refer to the
       descriptions of pmLoadASCIINameSpace(3) and pmLoadNameSpace(3) for details.

SYNTAX

       The general syntax for a non-leaf node in the PMNS is as follows

       pathname {
               name      [pmid]
               ...
       }

       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 distinguished.

       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 file.

       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                                   │
                         ├────────┼────────────────────────────────────────────┤
                         │  1-384 │ production PMDAs from PCP packages         │
                         ├────────┼────────────────────────────────────────────┤
                         │385-510 │ end-user PMDAs (allocate from high to low) │
                         ├────────┼────────────────────────────────────────────┤
                         │    511 │ reserved for dynamic PMNS entries          │
                         └────────┴────────────────────────────────────────────┘

EXAMPLE

       #define KERNEL 1
       #define FOO 387
       root {
           network
           cpu
           dynamic     FOO:*:*
       }

       #define NETWORK 26
       network {
           intrate     KERNEL:NETWORK:1
           packetrate
       }

       network.packetrate {
           in          KERNEL:NETWORK:35
           out         KERNEL:NETWORK:36
       }

       #define CPU 10
       cpu {
           syscallrate KERNEL:CPU:10
           util
       }

       #define USER 20
       #define SYSTEM 21
       #define IDLE 22

       cpu.util {
           user        KERNEL:CPU:USER
           sys         KERNEL:CPU:SYSTEM
           idle        KERNEL:CPU:IDLE
       }