pmdaroot(1) — Linux manual page


PMDAROOT(1)              General Commands Manual             PMDAROOT(1)

NAME         top

       pmdaroot - a privileged PMCD helper performance metrics domain

SYNOPSIS         top

       $PCP_PMDAS_DIR/root/pmdaroot [-d domain] [-l logfile] [-s

DESCRIPTION         top

       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.

INSTALLATION         top

       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.

FILES         top

              default help text file for metrics exported by the root
              default log file for error messages and other information
              from the root PMDA.
              default socket file for communication with root PMDA


       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

SEE ALSO         top

       PCPIntro(1), pmcd(1), PMDA(3), pmdaRootConnect(3), pcp.conf(5)
       and unix(7).

COLOPHON         top

       This page is part of the PCP (Performance Co-Pilot) project.
       Information about the project can be found at 
       ⟨⟩.  If you have a bug report for this manual
       page, send it to  This page was obtained from the
       project's upstream Git repository
       ⟨⟩ on 2023-12-22.
       (At that time, the date of the most recent commit that was found
       in the repository was 2023-12-16.)  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

Performance Co-Pilot               PCP                       PMDAROOT(1)

Pages that refer to this page: pmdarootconnect(3)