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PMDAMMV(1)									       PMDAMMV(1)

NAME
       pmdammv - memory mapped values performance metrics domain agent (PMDA)

SYNOPSIS
       $PCP_PMDAS_DIR/mmv/pmdammv [-d domain] [-l logfile] [-U username]

DESCRIPTION
       pmdammv	is a Performance Metrics Domain Agent (PMDA) which exports application level per-
       formance metrics using memory mapped files.  It offers an extremely low	overhead  instru-
       mentation  facility  that  is  well-suited  to long running, mission critical applications
       where it is desirable to have performance metrics and availability information permanently
       enabled.

       The  mmv  PMDA exports instrumentation that has been added to an application using the MMV
       APIs (refer to mmv_stats_init(3) and mmv(5) for	further  details).   These  APIs  can  be
       called  from  several languages, including C, C++, Perl, Python and Java (via the separate
       ``Parfait'' class library).

       A brief description of the pmdammv 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 mmv.log  is  written  in  the
	    current  directory	of  pmcd(1) when pmdammv 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.

       -U   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 default.

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

	    # cd $PCP_PMDAS_DIR/mmv
	    # ./Install

       Note that the default mechanism for sharing  memory  mapped  values  between  instrumented
       applications  and the mmv PMDA involves the creation of a world-writeable $PCP_TMP_DIR/mmv
       directory with the sticky-bit set (similar to /tmp and /var/tmp, for example).  This  suf-
       fices  to  allow  any application, running under any user account, to communicate with the
       PMDA (which runs under the "pcp" account by default).  This may not be desirable for every
       environment, and one should consider the security implications of any directory setup like
       this (similar classes of issues exist as those  that  affect  the  system  temporary  file
       directories).

       The installation process will not overwrite any existing $PCP_TMP_DIR/mmv directory.  Thus
       it is possible to implement an  alternate  permissions  strategy  with  no  world-writable
       directory for sharing files - any directory readable by user or group "pcp" will suffice.

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

	    # cd $PCP_PMDAS_DIR/mmv
	    # ./Remove

       pmdammv	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
       $PCP_PMCDCONF_PATH
		 command line options used to launch pmdammv
       $PCP_TMP_DIR/mmv
		 directory housing memory mapped value files
       $PCP_PMDAS_DIR/mmv/help
		 default help text file for the mmv metrics
       $PCP_PMDAS_DIR/mmv/Install
		 installation script for the pmdammv agent
       $PCP_PMDAS_DIR/mmv/Remove
		 undo installation script for the pmdammv agent
       $PCP_LOG_DIR/pmcd/mmv.log
		 default log file for error messages and other information from pmdammv

PCP ENVIRONMENT
       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 config-
       uration file, as described in pcp.conf(5).

SEE ALSO
       PCPIntro(1), pmcd(1), mmv_stats_init(3), mmv(5), pcp.conf(5) and pcp.env(5).

Performance Co-Pilot			       PCP				       PMDAMMV(1)
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