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