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PCPINTRO(1) General Commands Manual PCPINTRO(1)

NAME

PCPIntro - introduction to the Performance Co-Pilot (PCP)

INTRODUCTION

The Performance Co-Pilot (PCP) is a toolkit designed for monitoring and managing system-level performance. These services are distributed and scalable to accommodate the most complex system configurations and performance problems.

PCP supports many different platforms, including (but not limited to) Linux, MacOSX, Solaris and Windows. From a high-level PCP can be considered to contain two classes of software utility:

These are the parts of PCP that collect and extract performance data from various sources, for example the operating system kernel.
These are the parts of PCP that display data collected from hosts (or archives) that have the PCP Collector installed. Many monitor tools are available as part of the core PCP release, while other (typically graphical) monitoring tools are available separately in the PCP GUI package.

This manual entry describes the high-level features and options common to most PCP utilities available on all platforms.

OVERVIEW

The PCP architecture is distributed in the sense that any PCP tool may be executing remotely. On the host (or hosts) being monitored, each domain of performance metrics, whether the kernel, a service layer, a database management system, a web server, an application, etc. requires a Performance Metrics Domain Agent (PMDA) which is responsible for collecting performance measurements from that domain. All PMDAs are controlled by the Performance Metrics Collector Daemon (pmcd(1)) on the same host.

Client applications (the monitoring tools) connect to pmcd(1), which acts as a router for requests, by forwarding requests to the appropriate PMDA and returning the responses to the clients. Clients may also access performance data from sets of PCP archives (created using pmlogger(1)) for retrospective analysis.

Security philosophy

PCP redistributes a wealth of performance information within a host and across its networks. The following security philosophy underlies the setting of several defaults that control how much information is sent and received.

By default, the information exposed by PMCD about a host is approximately of the same level of confidentiality as available to a completely unprivileged user on that host. So, performance data that is available to be read completely freely on a machine may be made available by PMCD to the network.

However, the host running PMCD and its network is not assumed to run only friendly applications. Therefore, write type operations, including from the local host, are not permitted by default.

These defaults may be overridden (expanded or reduced) in several ways, including by specifying network ACLs in pmcd.conf, activating non-default PMDAs, or by using PMCD connections that pass user credentials. For example, some PMDAs automatically provide greater information for particular credentialed users or groups.

Applications

The following performance monitoring applications are primarily console based, typically run directly from the command line, and are just a small subset of the tools available as part of the base PCP package.

Each tool or command is documented completely in its own reference page.

Outputs an ASCII high-level summary of system performance.
An inference engine that can evaluate predicate-action rules to perform alarms and automate system management tasks.
Interrogate specific performance metrics and the metadata that describes them.
Generates PCP archives of performance metrics suitable for replay by most PCP tools.
Highly customizable performance metrics reporter with support for various different output modes.
Simple periodic reporting for some or all instances of a performance metric, with optional VCR time control.

If the PCP GUI package is installed then the following additional tools are available.

Displays trends over time of arbitrarily selected performance metrics from one or more hosts.
Time control utility for coordinating the time between multiple tools (including pmchart and pmval).
Produce ASCII reports for arbitrary combinations of performance metrics.

COMMON COMMAND LINE ARGUMENTS

There is a set of common command line arguments that are used consistently by most PCP tools.

Performance metric information is retrospectively retrieved from the set of Performance Co-Pilot (PCP) archives identified by archive previously generated by pmlogger(1). See LOGIMPORT(3) and LOGARCHIVE(5) for archive creation interfaces and format documentation.

archive is a comma-separated list of names, each of which may be the name of a directory containing one or more archives, the base name common to all of the physical files created by an instance of pmlogger(1), or any one of the physical files, e.g. /path/to/myarchives (directory) or myarchive (base name) or myarchive.meta (the metadata file) or myarchive.index (the temporal index) or myarchive.0 (the first data volume of archive) or myarchive.0.bz2 or myarchive.0.bz (the first data volume compressed with bzip2(1)) or myarchive.0.gz or myarchive.0.Z or myarchive.0.z (the first data volume compressed with gzip(1)), myarchive.1 or myarchive.3.bz2 or myarchive.42.gz etc.

Unless directed to another host by the -h (or --host) option, or to a set of archives by the -a (or --archive) option, the source of performance metrics will be the Performance Metrics Collector Daemon (PMCD) on the local host. Refer to the PMCD HOST SPECIFICATION section later for further details on the many options available when forming the host specification, as well as a detailed description of the default local host connection. The -a (or --archive), and -h (or --host) options are mutually exclusive.
The argument samples defines the number of samples to be retrieved and reported. If samples is 0 or -s (or --samples) is not specified, the application will sample and report continuously (in real time mode) or until the end of the set of PCP archives (in archive mode).
Change the reporting timezone to the local timezone at the host that is the source of the performance metrics, as identified via either the -h (or --host) or -a (or --archive) options.
By default, applications report the time of day according to the local timezone on the system where the application is executed. The -Z (or --timezone) option changes the timezone to timezone in the format of the environment variable TZ as described in environ(7).
Sets the PCP debugging options to debugspec to enable diagnostics and tracing that is most helpful for developers or when trying to diagnose the misbehaviour of a PCP application. debugspec should be a comma-separated list of debugging option name(s) and/or decimal integers, see pmdbg(1) for a description of the supported option names and values.

In the absence of a live or archive source of metrics, a heuristic search for archive logs for the local host can be invoked via the -O (or --origin) option. When using this option without an explicit source of metrics, monitor tools attempt to use archives from a system archive location such as $PCP_LOG_DIR/pmlogger/`hostname`. Refer to the TIME WINDOW SPECIFICATION section below for details on the acceptable syntax for the origin option, but a typical invocation in this mode would be -O today or --origin yesterday.

INTERVAL SPECIFICATION AND ALIGNMENT

Most PCP tools operate with periodic sampling or reporting, and the -t (or --interval) and -A (or --align) options may be used to control the duration of the sample interval and the alignment of the sample times.

Set the update or reporting interval.

The interval argument is specified as a sequence of one or more elements of the form



number[units]
where number is an integer or floating point constant (parsed using strtod(3)) and the optional units is one of: seconds, second, secs, sec, s, minutes, minute, mins, min, m, hours, hour, h, days, day and d. If the unit is empty, second is assumed.

In addition, the upper case (or mixed case) version of any of the above is also acceptable.

Spaces anywhere in the interval are ignored, so 4 days 6 hours 30 minutes, 4day6hour30min, 4d6h30m and 4d6.5h are all equivalent.

Multiple specifications are additive, for example ``1hour 15mins 30secs'' is interpreted as 3600+900+30 seconds.

By default samples are not necessarily aligned on any natural unit of time. The -A or --align option may be used to force the initial sample to be aligned on the boundary of a natural time unit. For example -A 1sec, -A 30min and --align 1hour specify alignment on whole seconds, half and whole hours respectively.

The align argument follows the syntax for an interval argument described above for the -t or --interval option.

Note that alignment occurs by advancing the time as required, and that -A (or --align) acts as a modifier to advance both the start of the time window (see the next section) and the origin time (if the -O or --origin option is specified).

TIME WINDOW SPECIFICATION

Many PCP tools are designed to operate in some time window of interest, for example to define a termination time for real-time monitoring or to define a start and end time within a set of PCP archive logs.

In the absence of the -O (or --origin) and -A (or --align) options to specify an initial sample time origin and time alignment (see above), the PCP application will retrieve the first sample at the start of the time window.

The following options may be used to specify a time window of interest.

By default the time window commences immediately in real-time mode, or coincides with time at the start of the set of PCP archive logs in archive mode. The -S or --start option may be used to specify a later time for the start of the time window.

The starttime parameter may be given in one of three forms (interval is the same as for the -t or --interval option as described above, datetime is described below):

To specify an offset from the current time (in real-time mode) or the beginning of a set of PCP archives (in archive mode) simply specify the interval of time as the argument. For example -S 30min will set the start of the time window to be exactly 30 minutes from now in real-time mode, or exactly 30 minutes from the start of a set of PCP archives.
To specify an offset from the end of a set of PCP archive logs, prefix the interval argument with a minus sign. In this case, the start of the time window precedes the time at the end of the set of archives by the given interval. For example -S -1hour will set the start of the time window to be exactly one hour before the time of the last sample in a set of PCP archive logs.
@datetime
To specify the calendar date and time (local time in the reporting timezone) for the start of the time window, use the datetime syntax preceded by an at sign. Refer to the datetime description below for detailed information.
By default the end of the time window is unbounded (in real-time mode) or aligned with the time at the end of a set of PCP archive logs (in archive mode). The -T or --finish option may be used to specify an earlier time for the end of the time window.

The endtime parameter may be given in one of three forms (interval is the same as for the -t or --interval option as described above, datetime is described below):

To specify an offset from the start of the time window simply use the interval of time as the argument. For example -T 2h30m will set the end of the time window to be 2 hours and 30 minutes after the start of the time window.
To specify an offset back from the time at the end of a set of PCP archive logs, prefix the interval argument with a minus sign. For example -T -90m will set the end of the time window to be 90 minutes before the time of the last sample in a set of PCP archive logs.
@datetime
To specify the calendar date and time (local time in the reporting timezone) for the end of the time window, use the datetime syntax preceded by an at sign. Refer to the datetime description below for detailed information.
By default samples are fetched from the start of the time window (see description of -S or --start option) to the end of the time window (see description of -T or --finish option). The -O or --origin option allows the specification of an origin within the time window to be used as the initial sample time. This is useful for interactive use of a PCP tool with the pmtime(1) VCR replay facility.

The origin argument accepted by -O (or --origin) conforms to the same syntax and semantics as the starttime argument for the -T (or --finish) option.

For example --origin -0 specifies that the initial position should be at the end of the time window; this is most useful when wishing to replay ``backwards'' within the time window.

The datetime argument for the -O (or --origin), -S (or --start) and -T (or --finish) options consists of:
date time zone day relative
A date can be one of: YY-MM-DD, MM/DD/YY, DD Month YYYY, or Month DD YYYY. A time can be one of: HH:MM:SS, HH:MM. HH:MM can use either the 12 hour (via an am or pm suffix) or 24 hour convention. A day of the week can be a spelled out day of the week, optionally preceded by an ordinal number such as second Tuesday. A zone is a time zone value as specified by the tzselect(8) command. A relative time can be a time unit that is: preceded by a cardinal number such as 1 year or 2 months, preceded by one of the time words this or last, or succeeded by the time word ago. A relative time can also be one of the time words: yesterday, today, tomorrow, now. Examples of datetime strings are: 1996-03-04 13:07:47 EST Mon, 1996-03-05 14:07:47 EST -1hour, Mon Mar 4 13:07:47 1996, Mar 4 1996, Mar 4, Mar, 13:07:50 or 13:08.

For any missing low order fields, the default value of 0 is assumed for hours, minutes and seconds, 1 for day of the month and Jan for months. Hence, the following are equivalent: --start '@ Mar 1996' and --start '@ Mar 1 00:00:00 1996'.

If any high order fields are missing, they are filled in by starting with the year, month and day from the current time (real-time mode) or the time at the beginning of the set of PCP archive logs (archive mode) and advancing the time until it matches the fields that are specified. So, for example if the time window starts by default at ``Mon Mar 4 13:07:47 1996'', then --start @13:10 corresponds to 13:10:00 on Mon Mar 4, 1996, while --start @10:00 corresponds to 10:00:00 on Tue Mar 5, 1996 (note this is the following day).

For greater precision than afforded by datetime(3), the seconds component may be a floating point number.

If a timezone is not included in a datetime then there ares several interpretations available depending on the other command line options used. The default is to use the local timezone on the system where the PCP tool is being run. A -Z or --timezone option specifies an explicit timezone, else a -z or --hostzone option changes the timezone to the local timezone at the host that is the source of the performance metrics.

PERFORMANCE METRICS - IDENTIFIERS, NAMES, VALUES

The number of performance metric names supported by PCP on most platforms ranges from many hundreds to several thousand. The PCP libraries and applications use an internal identification scheme that unambiguously associates a single integer with each known performance metric. This integer is known as the Performance Metric Identifier, or PMID. Although not a requirement, PMIDs tend to have global consistency across all systems, so a particular performance metric usually has the same PMID.

For all users and most applications, direct use of the PMIDs would be inappropriate (this would limit the range of accessible metrics, make the code hard to maintain, force the user interface to be particularly baroque, and so on). Hence a Performance Metrics Name Space (PMNS) is used to provide external names and a hierarchic classification for performance metrics. A PMNS is represented as a tree, with each node having a label, a pointer to either a PMID (for leaf nodes) or a set of descendent nodes in the PMNS (for non-leaf nodes).

A node label must begin with an alphabetic character, followed by zero or more characters drawn from the alphabetics, the digits and character ``_'' (underscore). For alphabetic characters in a node label, upper and lower case are distinguished.

By convention, the name of a performance metric is constructed by concatenation of the node labels on a path through the PMNS from the root node to a leaf node, with a ``.'' as a separator. The root node in the PMNS is unlabeled, so all names begin with the label associated with one of the descendent nodes below the root node of the PMNS, for example kernel.percpu.syscall. Typically (although this is not a requirement) there would be at most one name for each PMID in a PMNS. For example kernel.all.cpu.idle and disk.dev.read are the unique names for two distinct performance metrics, each with a unique PMID.

Groups of related PMIDs may be named by naming a non-leaf node in the PMNS tree, for example disk.

The default local PMNS used by pmcd is located at $PCP_VAR_DIR/pmns/root however the environment variable PMNS_DEFAULT may be set to the full pathname of a different PMNS which will then be used as the default local PMNS.

Most applications do not use the local PMNS directly, but rather import parts of the PMNS as required from the same place that performance metrics are fetched, i.e. from pmcd(1) for live monitoring or from a set of PCP archives for retrospective monitoring.

To explore the PMNS use pminfo(1), or if the PCP GUI package is installed the New Chart and Metric Search windows within pmchart(1).

Some performance metrics have a singular value. For example, the available memory or number of context switches have one value per performance metric source, that is, one value per host. The metric descriptor (metadata) for each metric makes this fact known to applications that process values for these single-valued metrics.

Some performance metrics have a set of values or instances in each implementing performance metric domain. For example, one value for each disk, one value for each process, one value for each CPU, or one value for each activation of a given application. When a metric has multiple instances, the PMNS does not represent this in metric names; rather, a single metric may have an associated set of values. Multiple values are associated with the members of an instance domain, such that each instance has a unique instance identifier within the associated instance domain. For example, the ''per CPU´´ instance domain may use the instance identifiers 0, 1, 2, 3, and so on to identify the configured processors in the system. Internally, instance identifiers are encoded as binary values, but each performance metric domain also supports corresponding strings as external names for the instance identifiers, and these names are used at the user interface to the PCP utilities.

Multiple performance metrics may be associated with a single instance domain. For example, per-process metrics under proc all share the same instance domain.

PCP arranges for information describing instance domains to be exported from the performance metric domains to the applications that require this information. Applications may also choose to retrieve values for all instances of a performance metric, or some arbitrary subset of the available instances.

Metric names and the instance domain concept provides two-dimensions for the modelling of performance metrics. This is a clear and simple model, however on some occasions it does not suffice. For example, a metric may wish to represent higher dimensional data such as ``per CPU'' counters for each running process. In these cases it is common to create a compound instance, where the name is composed of each component with a separator in-between (for example, ``87245::cpu7'' might be used to separate process ID from CPU ID) to create flattened instance names. Additionally, such cases benefit from the use of metric instances labels to explicitly show the separate components (continuing the example from above, labels ``{"pid":87245,"cpu":7}'' might be used).

PERFORMANCE METRIC SPECIFICATIONS

In configuration files and (to a lesser extent) command line options, metric specifications adhere to the following syntax rules by most tools. See the tool specific manual pages for the exact syntax supported.

If the source of performance metrics is real-time from pmcd(1) then the accepted syntax is
host:metric[instance1,instance2,...]

If the source of performance metrics is a set of PCP archive logs then the accepted syntax is
archive/metric[instance1,instance2,...]

The host:, archive/ and [instance1,instance2,...] components are all optional.

The , delimiter in the list of instance names may be replaced by white space.

Special characters in instance names may be escaped by surrounding the name in double quotes or preceding the character with a backslash.

White space is ignored everywhere except within a quoted instance name.

An empty instance is silently ignored, and in particular ``[]'' is the same as no instance, while ``[one,,,two]'' is parsed as specifying just the two instances ``one'' and ``two''.

As a special case, if the host is the single character ``@'' then this refers to a PM_CONTEXT_LOCAL source, see pmNewContext(3).

SECURE PMCD CONNECTIONS

Since PCP version 3.6.11, a monitor can explicitly request a secure connection to a collector host running pmcd(1) or pmproxy(1) using the PM_CTXFLAG_SECURE context flag. If the PCP Collector host supports this feature - refer to the pmcd.feature.secure metric for confirmation of this - a TLS/SSL (Transport Layer Security or Secure Sockets Layer) connection can be established which uses public key cryptography and related techniques. These features aim to prevent eavesdropping and data tampering from a malicious third party, as well as providing server-side authentication (confident identification of a server by a client) which can be used to guard against man-in-the-middle attacks.

A secure pmcd connection requires use of certificate-based authentication. The security features offered by pmcd and pmproxy are implemented using the OpenSSL APIs and utilities. The openssl(1) tool can be used to create certificates suitable for establishing trust between PCP monitor and collector hosts.

A complete description is beyond the scope of this document, refer to the PCP ENVIRONMENT, FILES and SEE ALSO sections for detailed information. This includes links to tutorials on the steps involved in setting up the available security features.

PMCD HOST SPECIFICATION

In the absence of an explicit hostname specification, most tools will default to the local host in live update mode. In PCP releases since 3.8.4 onward, this results in an efficient local protocol being selected - typically a Unix domain socket. If this option is used (which can also be explicitly requested via the unix: host specification described below), it is important to note that all connections will be automatically authenticated. In other words, the credentials of the user invoking a client tool will automatically be made available to pmcd(1) and all of its PMDAs, on the users behalf, such that results can be customized to the privilege levels of individual users.

Names of remote hosts running the pmcd(1) daemon can of course also be provided to request a remote host be used. The most basic form of pmcd host specification is a simple host name, possibly including the domain name if necessary. However, this can be extended in a number of ways to further refine attributes of the connection made to pmcd.

The pmcd port number and also optional pmproxy(1) hostname and its port number, can be given as part of the host specification, since PCP version 3.0. These supersede (and override) the old-style PMCD_PORT, PMPROXY_HOST and PMPROXY_PORT environment variables.

The following are valid hostname specifications that specify connections to pmcd on host nas1.acme.com with/without a list of ports, with/without a pmproxy(1) connection through a firewall, and with IPv6 and IPv4 addresses as shown.


$ pcp --host nas1.acme.com:44321,4321@firewall.acme.com:44322
$ pcp --host nas1.acme.com:44321@firewall.acme.com:44322
$ pcp --host nas1.acme.com:44321@firewall.acme.com
$ pcp --host nas1.acme.com@firewall.acme.com
$ pcp --host nas1.acme.com:44321
$ pcp --host [fe80::2ad2:44ff:fe88:e4f1%p2p1]
$ pcp --host 192.168.0.103

In addition, ``connection attributes'' can also be specified. These include username, password (can be given interactively and may depend on the authentication mechanism employed), whether to target a specific running container, whether to use secure (encrypted) or native (naked) protocol, and so on. The previous examples all default to native protocol, and use no authentication. This can be altered, as in the following examples.


$ pcp --host pcps://app2.acme.com?container=cae8e6edc0d5
$ pcp --host pcps://nas1.acme.com:44321?username=tanya&method=gssapi
$ pcp --host pcps://nas2.acme.com@firewalls.r.us?method=plain
$ pcp --host pcp://nas3.acme.com
$ pcp --host 192.168.0.103?container=cae8e6edc0d5,method=scram-sha-256
$ pcp --host unix:
$ pcp --host local:

The choice of authentication method, and other resulting parameters like username, optionally password, etc, depends on the SASL2 configuration used by each (remote) pmcd. Tutorials are available specifying various aspects of configuring the authentication module(s) used, these fine details are outside the scope of this document.

In all situations, host names can be used interchangeably with IPv4 or IPv6 addressing (directly), as shown above. In the case of an IPv6 address, the full address must be enclosed by square brackets and the scope (interface) must also be specified.

The final local: example above is now the default for most tools. This connection is an automatically authenticated local host connection on all platforms that support Unix domain sockets. No password is required and authentication is automatic. This is also the most efficient (lowest overhead) communication channel.

The difference between unix: and local: is that the former is a strict Unix domain socket specification (connection fails if it cannot connect that way), whereas the latter has a more forgiving fallback to using localhost (i.e. a regular Inet socket connection is used when Unix domain socket connections are unavailable).

FILES

/etc/pcp.conf
Configuration file for the PCP runtime environment, see pcp.conf(5).
/etc/pcp/tls.conf
Optionally contains OpenSSL configuration information, including locations of certificates providing trusted identification for collector and monitor hosts.
$HOME/.pcp
User-specific directories containing configuration files for customisation of the various monitor tools, such as pmchart(1).
$PCP_RC_DIR/pcp
Script for starting and stopping pmcd(1).
$PCP_PMCDCONF_PATH
Control file for pmcd(1).
$PCP_PMCDOPTIONS_PATH
Command line options passed to pmcd(1) when it is started from $PCP_RC_DIR/pcp. All the command line option lines should start with a hyphen as the first character. This file can also contain environment variable settings of the form "VARIABLE=value".
$PCP_BINADM_DIR
Location of PCP utilities for collecting and maintaining PCP archives, PMDA help text, PMNS files etc.
$PCP_PMDAS_DIR
Parent directory of the installation directory for Dynamic Shared Object (DSO) PMDAs.
$PCP_RUN_DIR/pmcd.pid
If pmcd is running, this file contains an ascii decimal representation of its process ID.
$PCP_LOG_DIR/pmcd
Default location of log files for pmcd(1), current directory for running PMDAs. Archives generated by pmlogger(1) are generally below $PCP_LOG_DIR/pmlogger.
$PCP_LOG_DIR/pmcd/pmcd.log
Diagnostic and status log for the current running pmcd(1) process. The first place to look when there are problems associated with pmcd.
$PCP_LOG_DIR/pmcd/pmcd.log.prev
Diagnostic and status log for the previous pmcd(1) instance.
$PCP_LOG_DIR/NOTICES
Log of pmcd(1) and PMDA starts, stops, additions and removals.
$PCP_VAR_DIR/config
Contains directories of configuration files for several PCP tools.
$PCP_SYSCONF_DIR/pmcd/rc.local
Local script for controlling PCP boot, shutdown and restart actions.
$PCP_VAR_DIR/pmns
Directory containing the set of PMNS files for all installed PMDAs.
$PCP_VAR_DIR/pmns/root
The ASCII PMNS(5) exported by pmcd(1) by default. This PMNS is be the super set of all other PMNS files installed in $PCP_VAR_DIR/pmns.

In addition, if the PCP product is installed the following files and directories are relevant.

$PCP_LOG_DIR/NOTICES
In addition to the pmcd(1) and PMDA activity, may be used to log alarms and notices from pmie(1) via pmpost(1).
$PCP_PMLOGGERCONTROL_PATH
Control file for pmlogger(1) instances launched from $PCP_RC_DIR/pcp and/or managed by pmlogger_check(1) and pmlogger_daily(1) as part of a production PCP archive collection setup.

ENVIRONMENT

In addition to the PCP run-time environment and configuration variables described in the PCP ENVIRONMENT section below, the following environment variables apply to all installations.

Note that most uses of these environment variables are optimized to check the environment only the first time the variable might be used. As the environment usually is not checked again, the only safe strategy is to ensure all PCP-related environment variables are set before the first call into any of the PCP libraries.

When set, allow clients to accept certificates with mismatched domain names with no prompt when they are sent by pmcd or other server components. See PCP_SECURE_SOCKETS.
When set, allow clients to accept self-signed certificates with no prompt when they are sent by pmcd or other server components. See PCP_SECURE_SOCKETS.
When set, this changes the default console from /dev/tty (on Unix) or CON: (on Windows) to be the specified console. The special value of none can be used to indicate no console is available for use. This is used in places where console-based tools need to interact with the user, and in particular is used when authentication is being performed.
When set, this variable provides an alternate to the -D command line option described above to initialize the diagnostic and debug options. The value for $PCP_DEBUG is the same as for the -D command line option, namely a comma-separated list of debugging option name(s), and/or decimal integers, see pmdbg(1) for a description of the supported option names and values.
When set, this variable defines a colon separated list of files and/or directories (the syntax is the same as for the $PATH variable for sh(1)). The components are expanded into a list of files as follows: if a component of $PCP_DERIVED_CONFIG is a file, then that file is added to the list, else if a component is a directory then recursive descent is used to enumerate all files below that directory and these are added to the list.

Each file in the resulting list is assumed to contain definitions of derived metrics as per the syntax described in pmLoadDerivedConfig(3), and these are loaded in order.

Derived metrics may be used to extend the available metrics with new (derived) metrics using simple arithmetic expressions.

If PCP_DERIVED_CONFIG is set, the derived metric definitions are processed automatically as each new source of performance metrics is established (i.e. each time a pmNewContext(3) is called) or when requests are made against the PMNS.

Any component in the $PCP_DERIVED_CONFIG list or the expanded list of files that is not a file, or is not a directory or is not accessible (due to permissions or a bad symbolic link) will be silently ignored.

When PCP archives logs are created there may be temporal gaps associated with discontinuities in the time series of logged data, for example when pmcd(1) is restarted or when multiple archive logs are concatenated with pmlogextract(1). These discontinuities are internally noted with a <mark> record in the PCP archive logs, and value interpolation as described in pmSetMode(3) is not supported across <mark> records (because the values before and after a <mark> record are not necessarily from a continuous time series). Sometimes the user knows the data semantics are sound in the region of the <mark> records, and $PCP_IGNORE_MARK_RECORDS may be used to suppress the default behaviour.

If PCP_IGNORE_MARK_RECORDS is set (but has no value) then all <mark> records will be ignored. Otherwise the value $PCP_IGNORE_MARK_RECORDS follows the syntax for an interval argument described above for the -t option, and <mark> records will be ignored if the time gap between the last record before the <mark> and the first record after the <mark> is not more than interval.

When set, this variable forces any monitor tool connections to be established using the certificate-based secure sockets feature. If the connections cannot be established securely, they will fail.
Specifies the location from which TLS (Transport Layer Security) configuration settings will be read. These settings are used by PCP client tools, pmcd and pmproxy whenever secure (encrypted) communication is requested.
Many PCP tools support the environment variable PCP_STDERR, which can be used to control where error messages are sent. When unset, the default behavior is that ``usage'' messages and option parsing errors are reported on standard error, other messages after initial startup are sent to the default destination for the tool, i.e. standard error for ASCII tools, or a dialog for GUI tools.

If PCP_STDERR is set to the literal value DISPLAY then all messages will be displayed in a dialog. This is used for any tools launched from a Desktop environment.

If PCP_STDERR is set to any other value, the value is assumed to be a filename, and all messages will be written there.

When attempting to connect to a remote pmcd(1) on a machine that is booting, the connection attempt could potentially block for a long time until the remote machine finishes its initialization. Most PCP applications and some of the PCP library routines will abort and return an error if the connection has not been established after some specified interval has elapsed. The default interval is 5 seconds. This may be modified by setting PMCD_CONNECT_TIMEOUT in the environment to a real number of seconds for the desired timeout. This is most useful in cases where the remote host is at the end of a slow network, requiring longer latencies to establish the connection correctly.
When a monitor or client application loses a connection to a pmcd(1), the connection may be re-established by calling a service routine in the PCP library. However, attempts to reconnect are controlled by a back-off strategy to avoid flooding the network with reconnection requests. By default, the back-off delays are 5, 10, 20, 40 and 80 seconds for consecutive reconnection requests from a client (the last delay will be repeated for any further attempts after the fifth). Setting the environment variable PMCD_RECONNECT_TIMEOUT to a comma separated list of positive integers will re-define the back-off delays, for example setting PMCD_RECONNECT_TIMEOUT to ``1,2'' will back-off for 1 second, then attempt another connection request every 2 seconds thereafter.
For monitor or client applications connected to pmcd(1), there is a possibility of the application "hanging" on a request for performance metrics or metadata or help text. These delays may become severe if the system running pmcd crashes, or the network connection is lost. By setting the environment variable PMCD_REQUEST_TIMEOUT to a number of seconds, requests to pmcd will timeout after this number of seconds. The default behavior is to be willing to wait 10 seconds for a response from every pmcd for all applications.

When pmcd(1) is started from $PCP_RC_DIR/pcp then the primary instance of pmlogger(1) will be started if the configuration flag pmlogger is chkconfig(8) or systemctl(1) enabled and pmcd is running and accepting connections.

The check on pmcd's readiness will wait up to PMCD_WAIT_TIMEOUT seconds. If pmcd has a long startup time (such as on a very large system), then PMCD_WAIT_TIMEOUT can be set to provide a maximum wait longer than the default 60 seconds.

If set, then interpreted as the full pathname to be used as the default local PMNS for pmLoadNameSpace(3). Otherwise, the default local PMNS is located at $PCP_VAR_DIR/pcp/pmns/root for base PCP installations.
Many of the performance metrics exported from PCP agents have the semantics of counter meaning they are expected to be monotonically increasing. Under some circumstances, one value of these metrics may smaller than the previously fetched value. This can happen when a counter of finite precision overflows, or when the PCP agent has been reset or restarted, or when the PCP agent is exporting values from some underlying instrumentation that is subject to some asynchronous discontinuity.

The environment variable PCP_COUNTER_WRAP may be set to indicate that all such cases of a decreasing ``counter'' should be treated as a counter overflow, and hence the values are assumed to have wrapped once in the interval between consecutive samples. This ``wrapping'' behavior was the default in earlier PCP versions, but by default has been disabled in PCP release from version 1.3 on.

The PMDA_PATH environment variable may be used to modify the search path used by pmcd(1) and pmNewContext(3) (for PM_CONTEXT_LOCAL contexts) when searching for a daemon or DSO PMDA. The syntax follows that for PATH in sh(1), i.e. a colon separated list of directories, and the default search path is ``/var/pcp/lib:/usr/pcp/lib'', (or ``/var/lib/pcp/lib'' on Linux, depending on the value of the $PCP_VAR_DIR environment variable).
The TCP/IP port(s) used by pmcd(1) to create the socket for incoming connections and requests, was historically 4321 and more recently the officially registered port 44321; in the current release, both port numbers are used by default as a transitional arrangement. This may be over-ridden by setting PMCD_PORT to a different port number, or a comma-separated list of port numbers. If a non-default port is used when pmcd is started, then every monitoring application connecting to that pmcd must also have PMCD_PORT set in their environment before attempting a connection.

The following environment variables are relevant to installations in which pmlogger(1), the PCP archive logger, is used.

The environment variable PMLOGGER_PORT may be used to change the base TCP/IP port number used by pmlogger(1) to create the socket to which pmlc(1) instances will try and connect. The default base port number is 4330. When used, PMLOGGER_PORT should be set in the environment before pmlogger is executed.
When pmlc(1) connects to pmlogger(1), there is a remote possibility of pmlc "hanging" on a request for information as a consequence of a failure of the network or pmlogger. By setting the environment variable PMLOGGER_REQUEST_TIMEOUT to a number of seconds, requests to pmlogger will timeout after this number of seconds. The default behavior is to be willing to wait forever for a response from each request to a pmlogger. When used, PMLOGGER_REQUEST_TIMEOUT should be set in the environment before pmlc is executed.

If you have the PCP product installed, then the following environment variables are relevant to the Performance Metrics Domain Agents (PMDAs).

Use this variable has been deprecated and it is now ignored. If the ``proc'' PMDA is configured as a DSO for use with pmcd(1) on the local host then all of the ``proc'' metrics will be available to applications using a PM_CONTEXT_LOCAL context.

The previous behaviour was that if this variable was set, then a context established with the type of PM_CONTEXT_LOCAL will have access to the ``proc'' PMDA to retrieve performance metrics about individual processes.

Use this variable has been deprecated and it is now ignored. If the ``sample'' PMDA is configured as a DSO for use with pmcd(1) on the local host then all of the ``sample'' metrics will be available to applications using a PM_CONTEXT_LOCAL context.

The previous behaviour was that if this variable was set, then a context established with the type of PM_CONTEXT_LOCAL will have access to the ``sample'' PMDA if this optional PMDA has been installed locally.

If set, pmieconf(1) will form its pmieconf(5) specification (set of parameterized pmie(1) rules) using all valid pmieconf files found below each subdirectory in this colon-separated list of subdirectories. If not set, the default is $PCP_VAR_DIR/config/pmieconf.

PCP ENVIRONMENT

Environment variables with the prefix PCP_ are used to parameterize the file and directory names used by PCP. On each installation, the file /etc/pcp.conf contains the local values for these variables. The $PCP_CONF variable may be used to specify an alternative configuration file, as described in pcp.conf(5).

For environment variables affecting PCP tools, see pmGetOptions(3).

SEE ALSO

pcp(1), pmcd(1), pmie(1), pmie_daily(1), pminfo(1), pmlc(1), pmlogger(1), pmlogger_daily(1), pmrep(1), pmstat(1), pmval(1), systemctl(1), LOGIMPORT(3), LOGARCHIVE(5), pcp.conf(5), pcp.env(5), PMNS(5) and chkconfig(8).

If the PCP GUI package is installed, then the following entries are also relevant:
pmchart(1), pmtime(1), and pmdumptext(1).

If the secure sockets extensions have been enabled, then the following references are also relevant:
https://pcp.io/documentation.html
https://pcp.readthedocs.io/en/latest/QG/EncryptedConnections.html
https://pcp.readthedocs.io/en/latest/QG/AuthenticatedConnections.html

Also refer to the books Performance Co-Pilot User's and Administrator's Guide and Performance Co-Pilot Programmer's Guide which can be found at https://pcp.readthedocs.io/en/latest/.

PCP Performance Co-Pilot