pmdapipe(1) — Linux manual page


PMDAPIPE(1)                General Commands Manual               PMDAPIPE(1)

NAME         top

       pmdapipe  -  command  output capture performance metrics domain agent

SYNOPSIS         top

       $PCP_PMDAS_DIR/pipe/pmdapipe [-c configfile] [-d domain] [-l logfile]
       [-m memory]

DESCRIPTION         top

       pmdapipe is a configurable command output monitoring Performance
       Metrics Domain Agent (PMDA).  It can be seen as analogous to a
       restricted shell, where options can be passed to preset commands, and
       each line of their output is converted into a performance event.
       These events can be consumed by client tools like pmval(1).

       The pipe PMDA exports both event-style metrics reflecting timestamped
       event records for text-oriented command output, as well as the more
       orthodox sample-style metrics such as event counts and throughput
       size values.

       The PMDA is configured via a configfile which contains one line for
       each process from which output can be captured, as described in the
       ``CONFIGURATION'' section below.

       A brief description of the pmdapipe command line options follows:

       -c   specifies an alternate configuration file for the PMDA.  By
            default, a file named $PCP_PMDAS_DIR/pipe/pipe.conf and any
            files below the $PCP_SYSCONF_DIR/pipe.conf.d/ directory are

       -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 pipe.log
            is written in the current directory of pmcd(1) when pmdapipe 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.

       -m   Limit the physical memory used by the PMDA to buffer event
            records to maxsize bytes.  As log events arrive at the PMDA,
            they must be buffered until individual client tools request the
            next batch since their previous batch of events.  The default
            maximum is 2 megabytes.


       The set of allowed pipe commands is configured by simple text
       file(s).  The format is a single line for each command followed by an
       optional access control section.

       Blank lines and comments are permitted (even encouraged) in the
       configuration file.  A comment begins with a ``#'' character and
       finishes at the end of the line.

       Each command configuration line is of the form:

              instance username command options


       instance      is a string identifying the pipe command, also exported
                     as the metric instance identifier.
       username      is the name of the user account under which the command
                     should run (e.g. "root")
       command       is the path to the binary which will be run to generate
                     piped output
       options       is an optional space-separated list of parameters to
                     pass to the command

                     This options list may contain numeric parameters
                     prefixed by the dollar-sign, and these will be
                     substituted with user-supplied values at the time the
                     command is run (similar to shell parameter

       Parameters are passed as a single space-separated or comma-separated
       string to the pipe.firehose metric, using the pmStore(3) interface.
       The pmval command provides store access via its -x option.  User-
       supplied parameters are restricted to containing alphanumeric

       The access control section of the file must start with a line of the


       Leading and trailing whitespace may appear around and within the
       brackets and the case of the access keyword is ignored.  No other
       text may appear on the line except a trailing comment.

       Following this line, the remainder of the configuration file should
       contain lines that allow or disallow use of commands from particular
       users or groups.

       User names and group names will be verified using the local
       /etc/passwd and /etc/groups files (or an alternative directory
       service), using the getpwent(3) and getgrent(3) routines.

       Access for users or groups are allowed or disallowed by specifying
       statements of the form:

              allow user username : instance
              disallow user username : instance
              allow group groupname : instance
              disallow group groupname : instance

       The username and groupname names will be verified using the local
       /etc/passwd and /etc/groups files (or an alternative directory
       service), using the getpwent(3) and getgrent(3) routines.

       The wildcard ``*'' can be used to refer to all instance names.

INSTALLATION         top

       If you want access to the names, help text and values for the pipe
       performance metrics, do the following as root:

            # cd $PCP_PMDAS_DIR/pipe
            # ./Install

       This is an interactive installation process which prompts for each
       log file path to be monitored (or command to be run), a metric
       instance name to identify it, and whether access should be restricted
       (refer to the -x option to pmval(1) for further details).

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

            # cd $PCP_PMDAS_DIR/pipe
            # ./Remove

       pmdapipe is launched by pmcd and should never be executed directly.
       The Install and Remove scripts notify pmcd when the agent is
       installed or removed.

EXAMPLES         top

       Following is a simple example of pmdapipe configuration and use of
       the pipe metrics to run the btrace command, by user bob:

            bob> cat $PCP_PMDAS_DIR/pipe/pipe.conf
            # instance      user      command
            rw_syscalls     root      perf script rw-by-file $1
            bdev_trace      root      btrace -w $1 /dev/$2

            allow user bob : *;
            allow user jane : bdev_trace;
            allow group perf : rw_syscalls;

            bob> pmval -i bdev_trace -x '5 sda' pipe.firehose
             8,2  5  1  0.000000000 25227  A  WS 734332384 + 24 <- (253,2) 734330336
             8,0  5  2  0.000000414 25227  A  WS 735358432 + 24 <- (8,2) 734332384
             8,0  5  3  0.000000756 25227  Q  WS 735358432 + 24 [qemu-kvm]
             [...5 seconds worth]

FILES         top

                 command line options used to launch pmdapipe
                 default configuration file for the pipe metrics
                 default help text file for the pipe metrics
                 installation script for the pmdapipe agent
                 undo installation script for the pmdapipe agent
                 default log file for error messages and other information
                 from pmdapipe
                 directory containing additional configuration files for the
                 pipe metrics


       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), pmval(1), pmcd(1), getpwent(3), getgrent(3), pmStore(3),
       pcp.conf(5) and pcp.env(5).

COLOPHON         top

       This page is part of the PCP (Performance Co-Pilot) project.
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       If you have a bug report for this manual page, send it to  This page was obtained from the project's upstream
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       2020-09-18.  (At that time, the date of the most recent commit that
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Performance Co-Pilot                 PCP                         PMDAPIPE(1)