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NAME | SYNOPSIS | DESCRIPTION | INSTALLATION | FILES | PCP ENVIRONMENT | DEBUGGING OPTIONS | SEE ALSO | COLOPHON |
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PMDAROOT(1) General Commands Manual PMDAROOT(1)
pmdaroot - a privileged PMCD helper performance metrics domain
agent
$PCP_PMDAS_DIR/root/pmdaroot [-D debug] [-d domain] [-l logfile]
[-s sockname]
pmdaroot is a special Performance Metrics Domain Agent (PMDA)
which cooperates closely with pmcd(1) and other PMDAs to provide
limited privileged services to these unprivileged processes.
In this role it is used to discover operating system containers
running on the local host. It also enables access to performance
data from within those containers by other PMDAs running on the
bare-metal host, using the pmdaRootConnect(3) and the associated
namespace interfaces.
Like all other PMDAs, it also exports performance metrics from the
domain it controls. Currently, this is limited to information
about the containers on the local system; currently Docker and LXC
containers can be detected.
If a non-default Docker parent-cgroup name is being used, this
value can be indicated to pmdaroot through addition of a
$PCP_SYSTEMD_CGROUP variable in /etc/pcp.conf.
-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
root.log is written in the current directory of pmcd(1) when
pmdaroot 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.
-s Location of the unix(7) domain socket for communication with
clients seeking privileged operations. By default, a socket
file named $PCP_TMP_DIR/pmcd/root.socket is used.
Access to the names, help text and values for the kernel
performance metrics is available by default - unlike most other
agents, no action is required to enable them and they should not
be removed.
$PCP_PMDAS_DIR/root/help
default help text file for metrics exported by the root
PMDA.
$PCP_LOG_DIR/pmcd/root.log
default log file for error messages and other information
from the root PMDA.
$PCP_VAR_DIR/pmcd/root.socket
default socket file for communication with root PMDA
clients.
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 pmdaroot are as follows:
┌────────┬───────────────────────────┐
│ Option │ Description │
├────────┼───────────────────────────┤
│ appl0 │ interactions with pmcd(1) │
├────────┼───────────────────────────┤
│ appl1 │ PMDA startup processing │
└────────┴───────────────────────────┘
PCPIntro(1), pmcd(1), PMDA(3), pmdaRootConnect(3), pcp.conf(5) and
unix(7).
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 PMDAROOT(1)
Pages that refer to this page: pmdarootconnect(3)
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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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