1msacc(3) Erlang Module Definition msacc(3)
2
6 msacc - Convenience functions for microstate accounting
7
9 This module implements some convenience functions for analyzing
10 microstate accounting data. For details about how to use the basic api
11 and what the different states represent see erlang:statis‐
12 tics(microstate_accounting).
13 Basic Scenario
15 1> msacc:start(1000).
17 ok
18 2> msacc:print().
19 Average thread real-time : 1000513 us
20 Accumulated system run-time : 2213 us
21 Average scheduler run-time : 1076 us
22 Thread aux check_io emulator gc other port sleep
24 Stats per thread:
26 async( 0) 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% 100.00%
27 async( 1) 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% 100.00%
28 aux( 1) 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% 99.99%
29 scheduler( 1) 0.00% 0.03% 0.13% 0.00% 0.01% 0.00% 99.82%
30 scheduler( 2) 0.00% 0.00% 0.00% 0.00% 0.03% 0.00% 99.97%
31 Stats per type:
33 async 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% 100.00%
34 aux 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% 99.99%
35 scheduler 0.00% 0.02% 0.06% 0.00% 0.02% 0.00% 99.89%
36 ok
37 This first command enables microstate accounting for 1000 milliseconds.
40 See start/0, stop/0, reset/0 and start/1 for more details. The second
41 command prints the statistics gathered during that time. First three
42 general statistics are printed.
43 Average real-time:
45 The average time spent collecting data in the threads. This should
46 be close to the time which data was collected.
47 System run-time:
49 The total run-time of all threads in the system. This is what you
50 get if you call msacc:stats(total_runtime,Stats).
51 Average scheduler run-time:
53 The average run-time for the schedulers. This is the average amount
54 of time the schedulers did not sleep.
55 Then one column per state is printed with a the percentage of time this
57 thread spent in the state out of it's own real-time. After the thread
58 specific time, the accumulated time for each type of thread is printed
59 in a similar format.
60 Since we have the average real-time and the percentage spent in each
62 state we can easily calculate the time spent in each state by multiply‐
63 ing Average thread real-time with Thread state %, i.e. to get the time
64 Scheduler 1 spent in the emulator state we do 1000513us * 0.13% =
65 1300us.
66
68 msacc_data() = [msacc_data_thread()]
69 msacc_data_thread() =
71 #{'$type' := msacc_data,
72 type := msacc_type(),
73 id := msacc_id(),
74 counters := msacc_data_counters()}
75 msacc_data_counters() = #{msacc_state() => integer() >= 0}
77 A map containing the different microstate accounting states and
79 the number of microseconds spent in it.
80 msacc_stats() = [msacc_stats_thread()]
82 msacc_stats_thread() =
84 #{'$type' := msacc_stats,
85 type := msacc_type(),
86 id := msacc_id(),
87 system := float(),
88 counters := msacc_stats_counters()}
89 A map containing information about a specific thread. The per‐
91 centages in the map can be either run-time or real-time depend‐
92 ing on if runtime or realtime was requested from stats/2. system
93 is the percentage of total system time for this specific thread.
94 msacc_stats_counters() =
96 #{msacc_state() => #{thread := float(), system := float()}}
97 A map containing the different microstate accounting states.
99 Each value in the map contains another map with the percentage
100 of time that this thread has spent in the specific state. Both
101 the percentage of system time and the time for that specific
102 thread is part of the map.
103 msacc_type() =
105 aux | async | dirty_cpu_scheduler | dirty_io_scheduler |
106 poll | scheduler
107 msacc_id() = integer() >= 0
109 msacc_state() =
111 alloc | aux | bif | busy_wait | check_io | emulator | ets |
112 gc | gc_fullsweep | nif | other | port | send | sleep | timers
113 The different states that a thread can be in. See erlang:sta‐
115 tistics(microstate_accounting) for details.
116 msacc_print_options() = #{system => boolean()}
118 The different options that can be given to print/2.
120
122 available() -> boolean()
123 This function checks whether microstate accounting is available
125 or not.
126 start() -> boolean()
128 Start microstate accounting. Returns whether it was previously
130 enabled or disabled.
131 start(Time) -> true
133 Types:
135 Time = timeout()
137 Resets all counters and then starts microstate accounting for
139 the given milliseconds.
140 stop() -> boolean()
142 Stop microstate accounting. Returns whether is was previously
144 enabled or disabled.
145 reset() -> boolean()
147 Reset microstate accounting counters. Returns whether is was
149 enabled or disabled.
150 print() -> ok
152 Prints the current microstate accounting to standard out. Same
154 as msacc:print(msacc:stats(),#{}).
155 print(DataOrStats) -> ok
157 Types:
159 DataOrStats = msacc_data() | msacc_stats()
161 Print the given microstate statistics values to stdout. Same as
163 msacc:print(DataOrStats,#{}).
164 print(DataOrStats, Options) -> ok
166 Types:
168 DataOrStats = msacc_data() | msacc_stats()
170 Options = msacc_print_options()
171 Print the given microstate statistics values to standard out.
173 With many states this can be quite verbose. See the top of this
174 reference manual for a brief description of what the fields
175 mean.
176 It is possible to print more specific types of statistics by
178 first manipulating the DataOrStats using stats/2. For instance
179 if you want to print the percentage of run-time for each thread
180 you can do:
181 msacc:print(msacc:stats(runtime,msacc:stats())).
183 If you want to only print run-time per thread type you can do:
185 msacc:print(msacc:stats(type,msacc:stats(runtime,msacc:stats()))).
187 Options
189 system:
191 Print percentage of time spent in each state out of system
192 time as well as thread time. Default: false.
193 print(FileOrDevice, DataOrStats, Options) -> ok
195 Types:
197 FileOrDevice = file:filename() | io:device()
199 DataOrStats = msacc_data() | msacc_stats()
200 Options = msacc_print_options()
201 Print the given microstate statistics values to the given file
203 or device. The other arguments behave the same way as for
204 print/2.
205 stats() -> msacc_data()
207 Returns a runtime system independent version of the microstate
209 statistics data presented by erlang:statis‐
210 tics(microstate_accounting). All counters have been normalized
211 to be in microsecond resolution.
212 stats(Analysis, Stats) -> integer() >= 0
214 Types:
216 Analysis = system_realtime | system_runtime
218 Stats = msacc_data()
219 Returns the system time for the given microstate statistics val‐
221 ues. System time is the accumulated time of all threads.
222 realtime:
224 Returns all time recorded for all threads.
225 runtime:
227 Returns all time spent doing work for all threads, i.e. all
228 time not spent in the sleep state.
229 stats(Analysis, Stats) -> msacc_stats()
231 Types:
233 Analysis = realtime | runtime
235 Stats = msacc_data()
236 Returns fractions of real-time or run-time spent in the various
238 threads from the given microstate statistics values.
239 stats(Analysis, StatsOrData) -> msacc_data() | msacc_stats()
241 Types:
243 Analysis = type
245 StatsOrData = msacc_data() | msacc_stats()
246 Returns a list of microstate statistics values where the values
248 for all threads of the same type has been merged.
249 to_file(Filename) -> ok | {error, file:posix()}
251 Types:
253 Filename = file:name_all()
255 Dumps the current microstate statistics counters to a file that
257 can be parsed with file:consult/1.
258 from_file(Filename) -> msacc_data()
260 Types:
262 Filename = file:name_all()
264 Read a file dump produced by to_file(Filename).
266Ericsson AB runtime_tools 1.14 msacc(3)