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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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PMDAPROC(1) General Commands Manual PMDAPROC(1)
pmdaproc - process performance metrics domain agent (PMDA)
$PCP_PMDAS_DIR/proc/pmdaproc [-AL] [-D debug] [-d domain] [-l
logfile] [-r cgroup] [-U username]
pmdaproc is a Performance Metrics Domain Agent (PMDA) which
extracts performance metrics describing the state of the
individual processes running on a Linux system.
The proc PMDA exports metrics that measure the memory, processor
and other resource use of each process, as well as summary
information collated across all of the running processes. The
PMDA uses credentials passed from the PMAPI(3) monitoring tool
identifying the user requesting the information, to ensure that
only values the user is allowed to access are returned by the
PMDA. This involves the PMDA temporarily changing its effective
user and group identifiers for the duration of requests for
instances and values. In other words, system calls to extract
information are performed as the user originating the request and
not as a privileged user. The mechanisms available for transfer
of user credentials are described further in the PCPIntro(1) page.
A brief description of the pmdaproc command line options follows:
-A Disables use of the credentials provided by PMAPI client
tools and simply runs everything under the "root" account.
Refer to the ACCESS CONFIGURATION section below for finer
grained control when using pmcd(1) with remote client
authentication. Only enable this option if you understand
the risks involved, and are sure that all remote accesses
will be from benevolent users. If enabled, unauthenticated
remote PMAPI clients will be able to access potentially
sensitive performance metric values which an unauthenticated
PMAPI client usually would not be able to. Refer to
CVE-2011-2495 and CVE-2012-3419 for additional details.
-L Changes the per-process instance domain used by most pmdaproc
metrics to include threads as well.
-d It is absolutely crucial that the performance metrics domain
number specified here is unique and consistent. That is,
domain should be different for every PMDA on the one host,
and the same domain number should be used for the same PMDA
on all hosts.
-l Location of the log file. By default, a log file named
proc.log is written in the current directory of pmcd(1) when
pmdaproc is started, i.e. $PCP_LOG_DIR/pmcd. If the log
file cannot be created or is not writable, output is written
to the standard error instead.
-r Restrict the set of processes exported in the per-process
instance domain to only those processes that are contained by
the specified cgroup resource container. This option
provides an optional finer granularity to the monitoring, and
can also be used to reduce the resources consumed by pmdaproc
during requests for instances and values.
-U User account under which to run the agent. The default is
the privileged "root" account, with seteuid (2) and setegid
(2) switching for accessing most information.
The pmdaproc Performance Metrics Domain Agent (PMDA) includes an
additional set of per-process metrics with an instance domain of
processes restricted to an "interesting" or "hot" set. Unlike the
stock metrics exported by the proc PMDA, which have an instance
domain equal to the current processes, hot metrics have an
instance domain which is a subset of this. This hotproc instance
domain is determined by a configurable predicate evaluated over
some refresh interval.
As well as the equivalent per-process proc metrics, hotproc
provides a cpuburn metric which specifies the CPU utilization of
the process over the refresh interval, total metrics which
indicate how much of the available CPU time the "interesting"
processes account for, predicate metrics which show the values of
the reserved variables (see below) that are being used in the
hotproc predicate, and control metrics for controlling the agent.
The configuration file consists of one predicate used to determine
if a process should be in the interesting set or not.
An example configuration file may be found at
$PCP_PMDAS_DIR/proc/samplehotproc.conf
This file with any modifications can be copied to
$PCP_PMDAS_DIR/proc/hotproc.conf in order to configure the hot
metrics. The pmstore(1) and pmStore(3) interfaces can be used as
well (described below).
The predicate is described using the language specified below.
The symbols are based on those used by the C(1) and awk(1)
languages.
Boolean Connectives
&& (and), || (or), ! (not), () (precedence overriding)
Number comparators
< , <= , > , >= , == , !=
String comparators
== , !=
String/Pattern comparators
~ (string matches pattern) , !~ (string does not match
pattern)
Reserved variables
uid (user id; type integer) uname (user name; type string),
gid (group id; type integer) gname (group name; type
string), fname (process file name; type string), psargs
(process file name with args; type string), cpuburn (cpu
utilization; type float), iodemand (I/O demand - Kbytes
read/written per second; type float), ctxswitch (number of
context switches per second; type float), syscalls (number
of system calls per second; type float), virtualsize
(virtual size in Kbytes; type float), residentsize
(resident size in Kbytes; type float), iowait (blocked and
raw io wait in secs/sec; type float), schedwait (time
waiting in run queue in secs/sec; type float).
Literal values
1234 (positive integer), 0.35 (positive float), "foobar"
(string; delimited by "), /[fF](o)+bar/ (pattern; delimited
by /), true (boolean), false (boolean)
Comments
#this is a comment (from # to the end of the line).
Examples
cpuburn > 0.2 # cpu utilization of more than 20%
cpuburn > 0.2 && uname == "root"
cpuburn > 0.2 && (uname == "root" || uname == "hot")
psargs ~ /pmda/ && cpuburn > 0.4
The hotproc.predicate metrics may be used to see what the values
of the reserved variables are that were used by the predicate at
the last refresh. They do not cover the reserved variables which
are already exported elsewhere. A hotproc.predicate metric may not
have a value if it is not referenced in the configuration
predicate.
The hot process metrics can also be configured at runtime through
the pmstore(1) interface (and, implicitly, the pmStore(3) API)
Examples
pmstore hotproc.control.config 'fname == "mingetty"'
pmstore hotproc.control.config 'uid == 0'
To force the config file to be reloaded:
pmstore hotproc.control.reload_config "1"
Access to per-process metrics is controlled by several factors.
When using automatically authenticating local connections, such as
through the "unix:" or "local:" style context, then client tools
will have full access to these metrics as if sampling the metrics
directly as the user running the client tool.
When using pmcd with remote, authenticated clients it is possible
to specify a set of user names that are allowed access to the
process metrics.
A configuration file $PCP_SYSCONF_DIR/proc/access.conf can be used
to fine-tune this behaviour, and it supports two keywords:
allowed
A comma-separated list of authenticated user names that
will be allowed access to per-process metrics. Sampling is
performed as the root user.
mapped A boolean value, when true indicating that authenticated
user names will be mapped to local system user account
names (this requires a one-to-one user name mapping between
the account and the SASL-based authenticated user name
enforced by pmcd(1)). Sampling is performed as that local
user.
The proc PMDA is installed and available by default. If you want
to undo the installation, do the following as root:
# cd $PCP_PMDAS_DIR/proc
# ./Remove
If you want to establish access to the names, help text and values
for the proc performance metrics once more, after removal, do the
following as root:
# cd $PCP_PMDAS_DIR/proc
# ./Install
pmdaproc is launched by pmcd(1) and should never be executed
directly. The Install and Remove scripts notify pmcd(1) when the
agent is installed or removed.
$PCP_PMCDCONF_PATH
command line options used to launch pmdaproc
$PCP_PMDAS_DIR/proc/help
default help text file for the proc metrics
$PCP_PMDAS_DIR/proc/Install
installation script for the pmdaproc agent
$PCP_PMDAS_DIR/proc/Remove
undo installation script for the pmdaproc agent
$PCP_LOG_DIR/pmcd/proc.log
default log file for error messages and other information
from pmdaproc
$PCP_PMDAS_DIR/proc/samplehotproc.conf
simple sample hotproc configuration
$PCP_PMDAS_DIR/proc/hotproc.conf
default hotproc configuration file
$PCP_SYSCONF_DIR/proc/access.conf
default access control configuration file
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).
The -D or --debug option enables the output of additional
diagnostics on stderr to help triage problems, although the
information is sometimes cryptic and primarily intended to provide
guidance for developers rather end-users. debug is a comma
separated list of debugging options; use pmdbg(1) with the -l
option to obtain a list of the available debugging options and
their meaning.
Debugging options specific to pmdaproc are as follows:
┌────────┬───────────────────────────────────────────────┐
│ Option │ Description │
├────────┼───────────────────────────────────────────────┤
│ appl0 │ cgroup handling │
├────────┼───────────────────────────────────────────────┤
│ appl1 │ refresh processing, including hotproc metrics │
├────────┼───────────────────────────────────────────────┤
│ appl2 │ PMNS operations │
├────────┼───────────────────────────────────────────────┤
│ appl3 │ process accounting metrics │
└────────┴───────────────────────────────────────────────┘
PCPIntro(1), pmcd(1), pmstore(1), seteuid(2), setegid(2),
PMAPI(3), pcp.conf(5) and pcp.env(5).
This page is part of the PCP (Performance Co-Pilot) project.
Information about the project can be found at
⟨http://www.pcp.io/⟩. If you have a bug report for this manual
page, send it to pcp@groups.io. This page was obtained from the
project's upstream Git repository
⟨https://github.com/performancecopilot/pcp.git⟩ on 2025-08-11.
(At that time, the date of the most recent commit that was found
in the repository was 2025-08-11.) If you discover any rendering
problems in this HTML version of the page, or you believe there is
a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
man-pages@man7.org
Performance Co-Pilot PCP PMDAPROC(1)
Pages that refer to this page: pcp-atop(1), pcp-atopsar(1), pmdaoverhead(1), pmda(3), LOGARCHIVE(5)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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