NAMEpmns - 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, 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
$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 (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 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. 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.
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PMNS(4)PMNS(4)
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.
PROCESSING FRAMEWORK
The PMNS specification is initially passed through cpp(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 #if ... #endif, etc.
When cpp(1) is executed, the ``standard'' include directories are the
current directory and $PCP_VAR_DIR/pmns.
SYNTAX
The general syntax for a non-leaf node in the PMNS is as follows
pathanme {
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 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
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PMNS(4)PMNS(4)
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 cpp(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.
The current allocation of the high-order (PMD or domain) component of
PMIDs is as follows.
___________________________________
Range Allocation
___________________________________
0 reserved
___________________________________
1-31 SGI internal
___________________________________
32-39 Oracle
___________________________________
40-47 Sybase
___________________________________
48-55 Informix
___________________________________
60 Linux
___________________________________
56-127 ISV Performance Metrics
___________________________________
128-254 End-user applications
___________________________________
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EXAMPLE
#define IRIX 1
root {
network
cpu
}
#define NETWORK 26
network {
intrate IRIX:NETWORK:1
packetrate
}
network.packetrate {
in IRIX:NETWORK:35
out IRIX:NETWORK:36
}
#define CPU 10
cpu {
syscallrate IRIX:CPU:10
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PMNS(4)PMNS(4)
util
}
#define USER 20
#define KERNEL 21
#define IDLE 22
cpu.util {
user IRIX:CPU:USER
sys IRIX:CPU:KERNEL
idle IRIX:CPU:IDLE
}
SEE ALSOPCPIntro(1), pmcd(1), pmnscomp(1), PCPIntro(3), PMAPI(3), pmErrStr(3),
pmGetConfig(3), pmLoadASCIINameSpace(3), pmLoadNameSpace(3), pcp.conf(4)
and pcp.env(4).
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