1MMV(5)                        File Formats Manual                       MMV(5)
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3
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NAME

6       mmv - Memory Mapped Values for Performance Co-Pilot
7

SYNOPSIS

9       $PCP_TMP_DIR/mmv/<file>
10

DESCRIPTION

12       The   files   in   $PCP_TMP_DIR/mmv   are   generated   either  by  the
13       mmv_stats_init(3) and mmv_stats2_init(3) functions from the  libpcp_mmv
14       library,  or  by a native language module such as Parfait (Java), Speed
15       (Golang) or Hornet (Rust).
16
17       There could be multiple files in this directory, each file representing
18       a  single source of the performance metrics.  The metrics are harvested
19       by pmdammv(1) which exports them to the rest  of  the  Performance  Co-
20       Pilot infrastructure.
21

FILE FORMAT

23       Each file starts with the following header:
24
25                    ┌───────┬────────┬──────────────────────────┐
26                    │Offset │ Length │           Name           │
27                    ├───────┼────────┼──────────────────────────┤
28                    │   0   │   4    │ tag == "MMV\0"           │
29                    ├───────┼────────┼──────────────────────────┤
30                    │   4   │   4    │ Version (1 or 2)         │
31                    ├───────┼────────┼──────────────────────────┤
32                    │   8   │   8    │ Generation 1             │
33                    ├───────┼────────┼──────────────────────────┤
34                    │  16   │   8    │ Generation 2             │
35                    ├───────┼────────┼──────────────────────────┤
36                    │  24   │   4    │ Number of TOC entries    │
37                    ├───────┼────────┼──────────────────────────┤
38                    │  28   │   4    │ Flags                    │
39                    ├───────┼────────┼──────────────────────────┤
40                    │  32   │   4    │ Process identifier (PID) │
41                    ├───────┼────────┼──────────────────────────┤
42                    │  36   │   4    │ Cluster identifier       │
43                    └───────┴────────┴──────────────────────────┘
44       The  version  number  specifies  which mapping layout format is in use.
45       There are two, both are very similar, as  described  below.   The  sole
46       purpose  of the MMV version 2 format is to allow the use of longer met‐
47       ric and instance names.  If names longer than MMV_NAMEMAX  are  not  in
48       use,  it  is best to use MMV version 1 format as this allows older ver‐
49       sions of PCP to also consume the data.  Support for v2 format was added
50       in the pcp-3.11.4 release.
51
52       The generation numbers are timestamps at the time of file creation, and
53       must match for the file to be considered by the MMV PMDA.
54
55       The flags can specify ways in which the client would like the MMV  PMDA
56       to  behave  - e.g. the MMV_FLAG_PROCESS flag specifies that only if the
57       process identified by PID is currently running should those  values  be
58       exported.
59
60       Finally, if set, the cluster identifier is a hint to the MMV PMDA as to
61       what cluster should be used with  this  application  when  forming  the
62       individual  metric  identifiers.   A performance metric identifier (see
63       PMDA(3)) consists of the PMDA domain number, the  cluster  number,  and
64       the individual item numbers described in the Metrics section.
65
66       The header is followed by at least 2 TOC sections: one section for met‐
67       rics and another for values.  The TOC section has the following format:
68
69           ┌───────┬────────┬─────────────────────────────────────────────┐
70           │Offset │ Length │                    Value                    │
71           ├───────┼────────┼─────────────────────────────────────────────┤
72           │  0    │   4    │ Section Type (see mmv_stats.h)              │
73           ├───────┼────────┼─────────────────────────────────────────────┤
74           │  4    │   4    │ Number of entries in the section            │
75           ├───────┼────────┼─────────────────────────────────────────────┤
76           │  8    │   8    │ Section's offset from the start of the file │
77           └───────┴────────┴─────────────────────────────────────────────┘
78       The section types are:
79
80              1: Indoms (instance domain definitions)
81
82              2: Instances
83
84              3: Metrics (metric definitions)
85
86              4: Values
87
88              5: String
89
90       The only  mandatory  sections  are  Metrics  and  Values.   Indoms  and
91       Instances  sections  of either version only appear if there are metrics
92       with multiple instances.  String sections only appear if there are met‐
93       rics  with  string values, when Metrics or Indoms are defined with help
94       text, or in v2 MMV format where metric names  and  instance  names  are
95       stored  in  string sections (providing significantly more space than v1
96       MMV format for these names).
97
98       The entries in the Indoms sections have the following format:
99
100              ┌───────┬────────┬───────────────────────────────────────┐
101              │Offset │ Length │                 Value                 │
102              ├───────┼────────┼───────────────────────────────────────┤
103              │   0   │   4    │ Unique serial number for this domain  │
104              ├───────┼────────┼───────────────────────────────────────┤
105              │   4   │   4    │ Number of entries in the domain       │
106              ├───────┼────────┼───────────────────────────────────────┤
107              │   8   │   8    │ Offset to first Instance or Instance2 │
108              ├───────┼────────┼───────────────────────────────────────┤
109              │  16   │   8    │ Short help text offset                │
110              ├───────┼────────┼───────────────────────────────────────┤
111              │  24   │   8    │ Long help text offset                 │
112              └───────┴────────┴───────────────────────────────────────┘
113       The entries in the Instances (v1) section have the following format:
114
115                  ┌───────┬────────┬───────────────────────────────┐
116                  │Offset │ Length │             Value             │
117                  ├───────┼────────┼───────────────────────────────┤
118                  │   0   │    8   │ Offset into the indom section │
119                  ├───────┼────────┼───────────────────────────────┤
120                  │   8   │    4   │ Unused padding (zero filled)  │
121                  ├───────┼────────┼───────────────────────────────┤
122                  │  12   │    4   │ Internal instance identifier  │
123                  ├───────┼────────┼───────────────────────────────┤
124                  │  16   │   64   │ External instance identifier  │
125                  └───────┴────────┴───────────────────────────────┘
126       The entries in the Instances (v2) section have the following format:
127
128           ┌───────┬────────┬────────────────────────────────────────────┐
129           │Offset │ Length │                   Value                    │
130           ├───────┼────────┼────────────────────────────────────────────┤
131           │   0   │   8    │ Offset into the indom section              │
132           ├───────┼────────┼────────────────────────────────────────────┤
133           │   8   │   4    │ Unused padding (zero filled)               │
134           ├───────┼────────┼────────────────────────────────────────────┤
135           │  12   │   4    │ Internal instance identifier               │
136           ├───────┼────────┼────────────────────────────────────────────┤
137           │  16   │   8    │ External instance identifier string offset │
138           └───────┴────────┴────────────────────────────────────────────┘
139       The entries in the Metrics (v1) section have the following format:
140
141                  ┌───────┬────────┬───────────────────────────────┐
142                  │Offset │ Length │             Value             │
143                  ├───────┼────────┼───────────────────────────────┤
144                  │   0   │   64   │ Metric Name                   │
145                  ├───────┼────────┼───────────────────────────────┤
146                  │  64   │    4   │ Metric Item (see PMDA(3))     │
147                  ├───────┼────────┼───────────────────────────────┤
148                  │  68   │    4   │ Metric Type (see mmv_stats.h) │
149                  ├───────┼────────┼───────────────────────────────┤
150                  │  72   │    4   │ Semantics (see PMAPI(3))      │
151                  ├───────┼────────┼───────────────────────────────┤
152                  │  76   │    4   │ Dimensions (see PMAPI(3))     │
153                  ├───────┼────────┼───────────────────────────────┤
154                  │  80   │    4   │ Instance Domain ID            │
155                  ├───────┼────────┼───────────────────────────────┤
156                  │  84   │    4   │ Unused padding (zero filled)  │
157                  ├───────┼────────┼───────────────────────────────┤
158                  │  88   │    8   │ Short help text offset        │
159                  ├───────┼────────┼───────────────────────────────┤
160                  │  96   │    8   │ Long help text offset         │
161                  └───────┴────────┴───────────────────────────────┘
162       The entries in the Metrics (v2) section have the following format:
163
164                  ┌───────┬────────┬───────────────────────────────┐
165                  │Offset │ Length │             Value             │
166                  ├───────┼────────┼───────────────────────────────┤
167                  │   0   │   8    │ Metric Name string offset     │
168                  ├───────┼────────┼───────────────────────────────┤
169                  │   8   │   4    │ Metric Item (see PMDA(3))     │
170                  ├───────┼────────┼───────────────────────────────┤
171                  │  12   │   4    │ Metric Type (see mmv_stats.h) │
172                  ├───────┼────────┼───────────────────────────────┤
173                  │  16   │   4    │ Semantics (see PMAPI(3))      │
174                  ├───────┼────────┼───────────────────────────────┤
175                  │  20   │   4    │ Dimensions (see PMAPI(3))     │
176                  ├───────┼────────┼───────────────────────────────┤
177                  │  24   │   4    │ Instance Domain ID            │
178                  ├───────┼────────┼───────────────────────────────┤
179                  │  28   │   4    │ Unused padding (zero filled)  │
180                  ├───────┼────────┼───────────────────────────────┤
181                  │  32   │   8    │ Short help text offset        │
182                  ├───────┼────────┼───────────────────────────────┤
183                  │  40   │   8    │ Long help text offset         │
184                  └───────┴────────┴───────────────────────────────┘
185       The entries in the Values section have the following format:
186
187               ┌───────┬────────┬────────────────────────────────────┐
188               │Offset │ Length │               Value                │
189               ├───────┼────────┼────────────────────────────────────┤
190               │   0   │   8    │ pmAtomValue (see PMAPI(3))         │
191               ├───────┼────────┼────────────────────────────────────┤
192               │   8   │   8    │ Extra space for STRING and ELAPSED │
193               ├───────┼────────┼────────────────────────────────────┤
194               │  16   │   8    │ Offset into the Metrics section    │
195               ├───────┼────────┼────────────────────────────────────┤
196               │  24   │   8    │ Offset into the Instances section  │
197               └───────┴────────┴────────────────────────────────────┘
198       Each entry in the strings section is a 256 byte character  array,  con‐
199       taining  a single NULL-terminated character string.  So each string has
200       a maximum length of 256 bytes, which includes the terminating NULL.
201

SEE ALSO

203       PCPIntro(1), pmdammv(1), PMAPI(3), mmv_stats_init(3),  pcp.conf(5)  and
204       pcp.env(5).
205
206
207
208Performance Co-Pilot                                                    MMV(5)
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