pmdatrace(1) — Linux manual page


PMDATRACE(1)               General Commands Manual              PMDATRACE(1)

NAME         top

       pmdatrace  - application-level transaction performance metrics domain

SYNOPSIS         top

       $PCP_PMDAS_DIR/trace/pmdatrace [-d domain] [-l logfile] [-A access]
       [-I port] [-M username] [-N buckets] [-T period] [-U units]

DESCRIPTION         top

       pmdatrace is a Performance Metrics Domain Agent (PMDA) which exports
       transaction performance metrics from application processes which use
       the pcp_trace library described in pmdatrace(3).

       A brief description of the pmdatrace command line options follows:

       -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
            trace.log is written in the current directory of pmcd(1) when
            pmdatrace 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.

       -A   Host-based access control for pmdatrace.  access must be either
            an allow or deny specification, using either
            allow:hostspec:maxconns or disallow:hostspec, where `allow' and
            `disallow' are keywords, `hostspec' is a host specification
            conforming to the format used by both pmcd(1) and pmlogger(1),
            and `maxconns' is the maximum number of connections allowed from
            a given `hostspec'.  Using a maximum connections of zero
            specifies an unlimited number of connections for the
            accompanying `hostspec'.

       -I   Communicate with pcp_trace clients via the given Internet port.
            This can alternatively be specified by setting $PCP_TRACE_PORT
            in the environment to some valid port number (use of the -I
            option overrides this).  The default port number is 4323.

       -T   period defines the aggregation period used to compute the recent
            averages and extrema.  Specified as a time interval using the
            syntax described in PCPIntro(1) for the common -t PCP argument,
            e.g. 30 seconds or 1 min.  The default is 60 seconds.

       -M   User account under which to run the agent.  The default is the
            unprivileged "pcp" account in current versions of PCP, but in
            older versions the superuser account ("root") was used by

       -N   Internally, the aggregation period is divided into bucket
            divisions, and the rolling average is recomputed every
            period/bucket seconds.  For example, the defaults correspond to
            -T 60 and -N 12, which means the average is recomputed every
            five seconds for a period covering the prior 60 seconds.

       -U   This option allows the dimension and scale associated with the
            observation value metric to be configured.  units is a comma-
            separated string of six integer values, which are the space
            dimension, time dimension, count dimension, space scale, time
            scale, and count scale, respectively.  The default dimension and
            scale is ``none'', which is equivalent to presenting
            ``0,0,0,0,0,0'' as the argument to -U.  The units associated
            with a metric are most easily viewed using the -d (metric
            description) option to pminfo(1).  The Install script described
            below steps through this option quite explicitly, so it is
            recommended that the Install script be used for building up the
            units specification.

       Essentially, the exported metrics provide statistics on the time for
       completion of each transaction, and an average count of transactions
       completed and watch points passed over a given time period.

INSTALLATION         top

       In order for a host to export the names, help text and values for the
       Trace performance metrics, do the following as root:

            # cd $PCP_PMDAS_DIR/trace
            # ./Install

       If you want to undo the installation, do the following as root:

            # cd $PCP_PMDAS_DIR/trace
            # ./Remove

       pmdatrace 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.

FILES         top

                 command line options used to launch pmdatrace
                 default help text file for the trace metrics
                 example programs which use the pcp_trace library
                 installation script for the pmdatrace agent
                 undo installation script for pmdatrace
                 default log file for error messages and other information
                 from pmdatrace


       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), pmtrace(1), PMAPI(3) and pmdatrace(3).

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                        PMDATRACE(1)

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