pmdaroot(1) — Linux manual page


PMDAROOT(1)                General Commands Manual               PMDAROOT(1)

NAME         top

       pmdaroot - a privileged PMCD helper performance metrics domain agent

SYNOPSIS         top

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

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

       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 pcp.conf(5).

SEE ALSO         top

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

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
       2020-08-13.  (At that time, the date of the most recent commit that
       was found in the repository was 2020-08-11.)  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

Performance Co-Pilot                 PCP                         PMDAROOT(1)

Pages that refer to this page: pmdarootconnect(3)pmdaRootConnect(3)pmdaRootContainerCGroupName(3)pmdaRootContainerHostName(3)pmdaRootContainerProcessID(3)pmdaRootProcessStart(3)pmdaRootProcessTerminate(3)pmdaRootProcessWait(3)pmdaRootShutdown(3)