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'\"macro stdmacro
.\"
.\" Copyright (c) 2014 Red Hat.
.\"
.\" This program is free software; you can redistribute it and/or modify it
.\" under the terms of the GNU General Public License as published by the
.\" Free Software Foundation; either version 2 of the License, or (at your
.\" option) any later version.
.\"
.\" This program is distributed in the hope that it will be useful, but
.\" WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
.\" or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
.\" for more details.
.\"
.TH PMDAMMV 1 "PCP" "Performance Co-Pilot"
.SH NAME
\f3pmdammv\f1 \- memory mapped values performance metrics domain agent (PMDA)
.SH SYNOPSIS
\f3$PCP_PMDAS_DIR/mmv/pmdammv\f1
[\f3\-d\f1 \f2domain\f1]
[\f3\-l\f1 \f2logfile\f1]
[\f3\-U\f1 \f2username\f1]
.SH DESCRIPTION
.B 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.
.PP
The
.B mmv
PMDA exports instrumentation that has been added to an application
using the MMV APIs (refer to
.BR mmv_stats_init (3)
and
.BR 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).
.PP
A brief description of the
.B pmdammv
command line options follows:
.TP 5
.B \-d
It is absolutely crucial that the performance metrics
.I domain
number specified here is unique and consistent.
That is,
.I domain
should be different for every PMDA on the one host, and the same
.I domain
number should be used for the same PMDA on all hosts.
.TP
.B \-l
Location of the log file. By default, a log file named
.I mmv.log
is written in the current directory of
.BR pmcd (1)
when
.B pmdammv
is started, i.e.
.BR $PCP_LOG_DIR/pmcd .
If the log file cannot
be created or is not writable, output is written to the standard error instead.
.TP
.B \-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.
.SH INSTALLATION
If you want access to the names, help text and values for the mmv
performance metrics, do the following as root:
.PP
.ft CW
.nf
.in +0.5i
# cd $PCP_PMDAS_DIR/mmv
# ./Install
.in
.fi
.ft 1
.PP
Note that the default mechanism for sharing memory mapped values
between instrumented applications and the
.B mmv
PMDA involves the creation of a world-writeable
.I $PCP_TMP_DIR/mmv
directory with the sticky-bit set (similar to
.I /tmp
and
.IR /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).
.PP
The installation process will not overwrite any existing
.I $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.
.PP
If you want to undo the installation, do the following as root:
.PP
.ft CW
.nf
.in +0.5i
# cd $PCP_PMDAS_DIR/mmv
# ./Remove
.in
.fi
.ft 1
.PP
.B pmdammv
is launched by
.BR pmcd (1)
and should never be executed directly.
The Install and Remove scripts notify
.BR pmcd (1)
when the agent is installed or removed.
.SH FILES
.PD 0
.TP 10
.B $PCP_PMCDCONF_PATH
command line options used to launch
.B pmdammv
.TP 10
.B $PCP_TMP_DIR/mmv
directory housing memory mapped value files
.TP 10
.B $PCP_PMDAS_DIR/mmv/help
default help text file for the mmv metrics
.TP 10
.B $PCP_PMDAS_DIR/mmv/Install
installation script for the
.B pmdammv
agent
.TP 10
.B $PCP_PMDAS_DIR/mmv/Remove
undo installation script for the
.B pmdammv
agent
.TP 10
.B $PCP_LOG_DIR/pmcd/mmv.log
default log file for error messages and other information from
.B pmdammv
.PD
.SH "PCP ENVIRONMENT"
Environment variables with the prefix
.B PCP_
are used to parameterize the file and directory names
used by PCP.
On each installation, the file
.I /etc/pcp.conf
contains the local values for these variables.
The
.B $PCP_CONF
variable may be used to specify an alternative
configuration file,
as described in
.BR pcp.conf (5).
.SH SEE ALSO
.BR PCPIntro (1),
.BR pmcd (1),
.BR mmv_stats_init (3),
.BR mmv (5),
.BR pcp.conf (5)
and
.BR pcp.env (5).
|
