Ubuntu Manpage: pmdammv - memory mapped values performance metrics domain agent (PMDA)

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
performance metrics using memory mapped files. It offers an extremely low overhead
instrumentation 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
       suffices 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