1PMDAMMV(1) General Commands Manual PMDAMMV(1)
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6 pmdammv - memory mapped values performance metrics domain agent (PMDA)
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9 $PCP_PMDAS_DIR/mmv/pmdammv [-d domain] [-l logfile] [-U username]
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12 pmdammv is a Performance Metrics Domain Agent (PMDA) which exports
13 application level performance metrics using memory mapped files. It
14 offers an extremely low overhead instrumentation facility that is well-
15 suited to long running, mission critical applications where it is
16 desirable to have performance metrics and availability information per‐
17 manently enabled.
18 The mmv PMDA exports instrumentation that has been added to an applica‐
20 tion using the MMV APIs (refer to mmv_stats_init(3) and mmv(5) for fur‐
21 ther details). These APIs can be called from several languages,
22 including C, C++, Perl, Python and Java (via the separate ``Parfait''
23 class library).
24 A brief description of the pmdammv command line options follows:
26 -d It is absolutely crucial that the performance metrics domain num‐
28 ber specified here is unique and consistent. That is, domain
29 should be different for every PMDA on the one host, and the same
30 domain number should be used for the same PMDA on all hosts.
31 -l Location of the log file. By default, a log file named mmv.log is
33 written in the current directory of pmcd(1) when pmdammv is
34 started, i.e. $PCP_LOG_DIR/pmcd. If the log file cannot be cre‐
35 ated or is not writable, output is written to the standard error
36 instead.
37 -U User account under which to run the agent. The default is the
39 unprivileged "pcp" account in current versions of PCP, but in
40 older versions the superuser account ("root") was used by default.
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43 If you want access to the names, help text and values for the mmv per‐
44 formance metrics, do the following as root:
45 # cd $PCP_PMDAS_DIR/mmv
47 # ./Install
48 Note that the default mechanism for sharing memory mapped values
50 between instrumented applications and the mmv PMDA involves the cre‐
51 ation of a world-writeable $PCP_TMP_DIR/mmv directory with the sticky-
52 bit set (similar to /tmp and /var/tmp, for example). This suffices to
53 allow any application, running under any user account, to communicate
54 with the PMDA (which runs under the "pcp" account by default). This
55 may not be desirable for every environment, and one should consider the
56 security implications of any directory setup like this (similar classes
57 of issues exist as those that affect the system temporary file directo‐
58 ries).
59 The installation process will not overwrite any existing
61 $PCP_TMP_DIR/mmv directory. Thus it is possible to implement an alter‐
62 nate permissions strategy with no world-writable directory for sharing
63 files - any directory readable by user or group "pcp" will suffice.
64 If you want to undo the installation, do the following as root:
66 # cd $PCP_PMDAS_DIR/mmv
68 # ./Remove
69 pmdammv is launched by pmcd(1) and should never be executed directly.
71 The Install and Remove scripts notify pmcd(1) when the agent is
72 installed or removed.
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75 $PCP_PMCDCONF_PATH
76 command line options used to launch pmdammv
77 $PCP_TMP_DIR/mmv
78 directory housing memory mapped value files
79 $PCP_PMDAS_DIR/mmv/help
80 default help text file for the mmv metrics
81 $PCP_PMDAS_DIR/mmv/Install
82 installation script for the pmdammv agent
83 $PCP_PMDAS_DIR/mmv/Remove
84 undo installation script for the pmdammv agent
85 $PCP_LOG_DIR/pmcd/mmv.log
86 default log file for error messages and other information
87 from pmdammv
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90 Environment variables with the prefix PCP_ are used to parameterize the
91 file and directory names used by PCP. On each installation, the file
92 /etc/pcp.conf contains the local values for these variables. The
93 $PCP_CONF variable may be used to specify an alternative configuration
94 file, as described in pcp.conf(5).
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97 PCPIntro(1), pmcd(1), mmv_stats_init(3), mmv(5), pcp.conf(5) and
98 pcp.env(5).
99Performance Co-Pilot PCP PMDAMMV(1)