1instrument(3)              Erlang Module Definition              instrument(3)
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NAME

6       instrument - Analysis and Utility Functions for Instrumentation
7

DESCRIPTION

9       The  module instrument contains support for studying the resource usage
10       in an Erlang runtime system. Currently, only the allocation  of  memory
11       can be studied.
12
13   Note:
14       Note  that  this  whole module is experimental, and the representations
15       used as well as the functionality is likely to change in the future.
16
17

DATA TYPES

19       block_histogram() = tuple()
20
21              A histogram of block sizes where each interval's upper bound  is
22              twice as high as the one before it.
23
24              The  upper  bound of the first interval is provided by the func‐
25              tion that returned the histogram, and the last interval  has  no
26              upper bound.
27
28       allocation_summary() =
29           {HistogramStart :: integer() >= 0,
30            UnscannedSize :: integer() >= 0,
31            Allocations ::
32                #{Origin :: atom() =>
33                      #{Type :: atom() => block_histogram()}}}
34
35              A  summary  of  allocated  block sizes (including their headers)
36              grouped by their Origin and Type.
37
38              Origin is generally which  NIF  or  driver  that  allocated  the
39              blocks, or 'system' if it could not be determined.
40
41              Type  is the allocation category that the blocks belong to, e.g.
42              db_term, message or binary.
43
44              If one or more carriers could not be  scanned  in  full  without
45              harming  the  responsiveness of the system, UnscannedSize is the
46              number of bytes that had to be skipped.
47
48       carrier_info_list() =
49           {HistogramStart :: integer() >= 0,
50            Carriers ::
51                [{AllocatorType :: atom(),
52                  InPool :: boolean(),
53                  TotalSize :: integer() >= 0,
54                  UnscannedSize :: integer() >= 0,
55                  Allocations ::
56                      {Type :: atom(),
57                       Count :: integer() >= 0,
58                       Size :: integer() >= 0},
59                  FreeBlocks :: block_histogram()}]}
60
61              AllocatorType is the type of the  allocator  that  employs  this
62              carrier.
63
64              InPool is whether the carrier is in the migration pool.
65
66              TotalSize  is  the  total  size  of  the  carrier, including its
67              header.
68
69              Allocations is a summary of the allocated blocks in the carrier.
70
71              FreeBlocks is a histogram of the free block sizes  in  the  car‐
72              rier.
73
74              If  the carrier could not be scanned in full without harming the
75              responsiveness of the system, UnscannedSize  is  the  number  of
76              bytes that had to be skipped.
77

EXPORTS

79       allocations() -> {ok, Result} | {error, Reason}
80
81              Types:
82
83                 Result = allocation_summary()
84                 Reason = not_enabled
85
86              Shorthand for allocations(#{}).
87
88       allocations(Options) -> {ok, Result} | {error, Reason}
89
90              Types:
91
92                 Result = allocation_summary()
93                 Reason = not_enabled
94                 Options =
95                     #{scheduler_ids => [integer() >= 0],
96                       allocator_types => [atom()],
97                       histogram_start => integer() >= 1,
98                       histogram_width => integer() >= 1}
99
100              Returns  a  summary of all tagged allocations in the system, op‐
101              tionally filtered by allocator type and scheduler id.
102
103              Only binaries and allocations  made  by  NIFs  and  drivers  are
104              tagged by default, but this can be configured an a per-allocator
105              basis with the +M<S>atags emulator option.
106
107              If the specified allocator types are not enabled, the call  will
108              fail with {error, not_enabled}.
109
110              The following options can be used:
111
112                allocator_types:
113                  The  allocator types that will be searched. Note that blocks
114                  can move freely between allocator types, so restricting  the
115                  search  to  certain  allocators  may return unexpected types
116                  (e.g. process heaps when searching  binary_alloc),  or  hide
117                  blocks that were migrated out.
118
119                  Defaults to all alloc_util allocators.
120
121                scheduler_ids:
122                  The   scheduler   ids  whose  allocator  instances  will  be
123                  searched. A scheduler id of 0 will refer to the  global  in‐
124                  stance  that  is  not  tied to any particular scheduler. De‐
125                  faults to all schedulers and the global instance.
126
127                histogram_start:
128                  The upper bound of the first interval in the allocated block
129                  size histograms. Defaults to 128.
130
131                histogram_width:
132                  The  number  of  intervals  in the allocated block size his‐
133                  tograms. Defaults to 18.
134
135              Example:
136
137              > instrument:allocations(#{ histogram_start => 128, histogram_width => 15 }).
138              {ok,{128,0,
139                   #{udp_inet =>
140                         #{driver_event_state => {0,0,0,0,0,0,0,0,0,1,0,0,0,0,0}},
141                     system =>
142                         #{heap => {0,0,0,0,20,4,2,2,2,3,0,1,0,0,1},
143                           db_term => {271,3,1,52,80,1,0,0,0,0,0,0,0,0,0},
144                           code => {0,0,0,5,3,6,11,22,19,20,10,2,1,0,0},
145                           binary => {18,0,0,0,7,0,0,1,0,0,0,0,0,0,0},
146                           message => {0,40,78,2,2,0,0,0,0,0,0,0,0,0,0},
147                           ... }
148                     spawn_forker =>
149                         #{driver_select_data_state =>
150                               {1,0,0,0,0,0,0,0,0,0,0,0,0,0,0}},
151                     ram_file_drv => #{drv_binary => {0,0,0,0,0,0,1,0,0,0,0,0,0,0,0}},
152                     prim_file =>
153                         #{process_specific_data => {2,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
154                           nif_trap_export_entry => {0,4,0,0,0,0,0,0,0,0,0,0,0,0,0},
155                           monitor_extended => {0,1,0,0,0,0,0,0,0,0,0,0,0,0,0},
156                           drv_binary => {0,0,0,0,0,0,1,0,3,5,0,0,0,1,0},
157                           binary => {0,4,0,0,0,0,0,0,0,0,0,0,0,0,0}},
158                     prim_buffer =>
159                         #{nif_internal => {0,4,0,0,0,0,0,0,0,0,0,0,0,0,0},
160                           binary => {0,4,0,0,0,0,0,0,0,0,0,0,0,0,0}}}}}
161
162
163       carriers() -> {ok, Result} | {error, Reason}
164
165              Types:
166
167                 Result = carrier_info_list()
168                 Reason = not_enabled
169
170              Shorthand for carriers(#{}).
171
172       carriers(Options) -> {ok, Result} | {error, Reason}
173
174              Types:
175
176                 Result = carrier_info_list()
177                 Reason = not_enabled
178                 Options =
179                     #{scheduler_ids => [integer() >= 0],
180                       allocator_types => [atom()],
181                       histogram_start => integer() >= 1,
182                       histogram_width => integer() >= 1}
183
184              Returns a summary of all carriers in the system, optionally fil‐
185              tered by allocator type and scheduler id.
186
187              If  the specified allocator types are not enabled, the call will
188              fail with {error, not_enabled}.
189
190              The following options can be used:
191
192                allocator_types:
193                  The allocator types that will be searched. Defaults  to  all
194                  alloc_util allocators.
195
196                scheduler_ids:
197                  The   scheduler   ids  whose  allocator  instances  will  be
198                  searched. A scheduler id of 0 will refer to the  global  in‐
199                  stance  that  is  not  tied to any particular scheduler. De‐
200                  faults to all schedulers and the global instance.
201
202                histogram_start:
203                  The upper bound of the first interval in the free block size
204                  histograms. Defaults to 512.
205
206                histogram_width:
207                  The  number  of intervals in the free block size histograms.
208                  Defaults to 14.
209
210              Example:
211
212              > instrument:carriers(#{ histogram_start => 512, histogram_width => 8 }).
213              {ok,{512,
214                   [{ll_alloc,1048576,0,1048344,71,false,{0,0,0,0,0,0,0,0}},
215                    {binary_alloc,1048576,0,324640,13,false,{3,0,0,1,0,0,0,2}},
216                    {eheap_alloc,2097152,0,1037200,45,false,{2,1,1,3,4,3,2,2}},
217                    {fix_alloc,32768,0,29544,82,false,{22,0,0,0,0,0,0,0}},
218                    {...}|...]}}
219
220

SEE ALSO

222       erts_alloc(3), erl(1)
223
224
225
226Ericsson AB                       tools 3.5.2                    instrument(3)
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