View Source msacc (runtime_tools v2.1)
Convenience functions for microstate accounting
This module implements some convenience functions for analyzing microstate
accounting data. For details about how to use the basic API and what the
different states represent, see
erlang:statistics(microstate_accounting).
Basic Scenario
1> msacc:start(1000).
ok
2> msacc:print().
Average thread real-time : 1000513 us
Accumulated system run-time : 2213 us
Average scheduler run-time : 1076 us
Thread aux check_io emulator gc other port sleep
Stats per thread:
async( 0) 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% 100.00%
async( 1) 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% 100.00%
aux( 1) 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% 99.99%
scheduler( 1) 0.00% 0.03% 0.13% 0.00% 0.01% 0.00% 99.82%
scheduler( 2) 0.00% 0.00% 0.00% 0.00% 0.03% 0.00% 99.97%
Stats per type:
async 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% 100.00%
aux 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% 99.99%
scheduler 0.00% 0.02% 0.06% 0.00% 0.02% 0.00% 99.89%
okThis first command enables microstate accounting for 1000 milliseconds. See
start/0, stop/0, reset/0, and start/1 for more details. The second
command prints the statistics gathered during that time. First three general
statistics are printed.
Average real-time - The average time spent collecting data in the threads. This should be close to the time which data was collected.
System run-time - The total run-time of all threads in the system. This is what you get if you call
msacc:stats(total_runtime,Stats).Average scheduler run-time - The average run-time for the schedulers. This is the average amount of time the schedulers did not sleep.
Then one column per state is printed with a the percentage of time this thread spent in the state out of it's own real-time. After the thread specific time, the accumulated time for each type of thread is printed in a similar format.
Since we have the average real-time and the percentage spent in each state we
can easily calculate the time spent in each state by multiplying
Average thread real-time with Thread state %, that is, to get the time Scheduler
1 spent in the emulator state we do 1000513us * 0.13% = 1300us.
Summary
Types
A map containing the different microstate accounting states and the number of microseconds spent in it.
The different options that can be given to print/2.
The different states that a thread can be in. See erlang:statistics(microstate_accounting) for details.
A map containing the different microstate accounting states. Each value in the
map contains another map with the percentage of time that this thread has spent
in the specific state. Both the percentage of system time and the time for
that specific thread is part of the map.
A map containing information about a specific thread. The percentages in the map
can be either run-time or real-time depending on if runtime or realtime was
requested from stats/2. system is the percentage of total system time for
this specific thread.
Functions
This function checks whether microstate accounting is available or not.
Read a file dump produced by to_file(Filename).
Prints the current microstate accounting to standard out. Equivalent to
msacc:print(msacc:stats(), #{}).
Equivalent to print(DataOrStats, #{}).
Print the given microstate statistics values to standard out. With many states this can be verbose. See the top of this reference manual for a brief description of what the fields mean.
Print the given microstate statistics values to the given file or device. The
other arguments behave the same way as for print/2.
Reset microstate accounting counters. Returns whether is was enabled or disabled.
Start microstate accounting. Returns whether it was previously enabled or disabled.
Resets all counters and then starts microstate accounting for the given milliseconds.
Returns a runtime system independent version of the microstate statistics data
presented by
erlang:statistics(microstate_accounting).
All counters have been normalized to be in microsecond resolution.
Returns the system time for the given microstate statistics values. System time is the accumulated time of all threads.
Stop microstate accounting. Returns whether is was previously enabled or disabled.
Dumps the current microstate statistics counters to a file that can be parsed
with file:consult/1.
Types
-type msacc_data() :: [msacc_data_thread()].
-type msacc_data_counters() :: #{msacc_state() => non_neg_integer()}.
A map containing the different microstate accounting states and the number of microseconds spent in it.
-type msacc_data_thread() :: #{'$type' := msacc_data, type := msacc_type(), id := msacc_id(), counters := msacc_data_counters()}.
-type msacc_id() :: non_neg_integer().
-type msacc_print_options() :: #{system => boolean()}.
The different options that can be given to print/2.
-type msacc_state() ::
alloc | aux | bif | busy_wait | check_io | emulator | ets | gc | gc_fullsweep | nif | other |
port | send | sleep | timers.
The different states that a thread can be in. See erlang:statistics(microstate_accounting) for details.
-type msacc_stats() :: [msacc_stats_thread()].
-type msacc_stats_counters() :: #{msacc_state() => #{thread := float(), system := float()}}.
A map containing the different microstate accounting states. Each value in the
map contains another map with the percentage of time that this thread has spent
in the specific state. Both the percentage of system time and the time for
that specific thread is part of the map.
-type msacc_stats_thread() :: #{'$type' := msacc_stats, type := msacc_type(), id := msacc_id(), system := float(), counters := msacc_stats_counters()}.
A map containing information about a specific thread. The percentages in the map
can be either run-time or real-time depending on if runtime or realtime was
requested from stats/2. system is the percentage of total system time for
this specific thread.
-type msacc_type() :: aux | async | dirty_cpu_scheduler | dirty_io_scheduler | poll | scheduler.
Functions
-spec available() -> boolean().
This function checks whether microstate accounting is available or not.
-spec from_file(Filename) -> msacc_data() when Filename :: file:name_all().
Read a file dump produced by to_file(Filename).
-spec print() -> ok.
Prints the current microstate accounting to standard out. Equivalent to
msacc:print(msacc:stats(), #{}).
-spec print(DataOrStats) -> ok when DataOrStats :: msacc_data() | msacc_stats().
Equivalent to print(DataOrStats, #{}).
-spec print(DataOrStats, Options) -> ok when DataOrStats :: msacc_data() | msacc_stats(), Options :: msacc_print_options().
Print the given microstate statistics values to standard out. With many states this can be verbose. See the top of this reference manual for a brief description of what the fields mean.
It is possible to print more specific types of statistics by first manipulating
the DataOrStats using stats/2. For instance if you want to print the
percentage of run-time for each thread you can do:
msacc:print(msacc:stats(runtime, msacc:stats())).If you want to only print run-time per thread type you can do:
msacc:print(msacc:stats(type, msacc:stats(runtime, msacc:stats()))).Options
system- Print percentage of time spent in each state out of system time as well as thread time. Default: false.
-spec print(FileOrDevice, DataOrStats, Options) -> ok when FileOrDevice :: file:filename() | io:device(), DataOrStats :: msacc_data() | msacc_stats(), Options :: msacc_print_options().
Print the given microstate statistics values to the given file or device. The
other arguments behave the same way as for print/2.
-spec reset() -> boolean().
Reset microstate accounting counters. Returns whether is was enabled or disabled.
-spec start() -> boolean().
Start microstate accounting. Returns whether it was previously enabled or disabled.
-spec start(Time) -> true when Time :: timeout().
Resets all counters and then starts microstate accounting for the given milliseconds.
-spec stats() -> msacc_data().
Returns a runtime system independent version of the microstate statistics data
presented by
erlang:statistics(microstate_accounting).
All counters have been normalized to be in microsecond resolution.
-spec stats(Analysis, Stats) -> non_neg_integer() when Analysis :: system_realtime | system_runtime, Stats :: msacc_data(); (Analysis, Stats) -> msacc_stats() when Analysis :: realtime | runtime, Stats :: msacc_data(); (Analysis, StatsOrData) -> msacc_data() | msacc_stats() when Analysis :: type, StatsOrData :: msacc_data() | msacc_stats().
Returns the system time for the given microstate statistics values. System time is the accumulated time of all threads.
realtime- Returns all time recorded for all threads.runtime- Returns all time spent doing work for all threads, i.e. all time not spent in thesleepstate.
Returns fractions of real-time or run-time spent in the various threads from the given microstate statistics values.
Returns a list of microstate statistics values where the values for all threads of the same type has been merged.
-spec stop() -> boolean().
Stop microstate accounting. Returns whether is was previously enabled or disabled.
-spec to_file(Filename) -> ok | {error, file:posix()} when Filename :: file:name_all().
Dumps the current microstate statistics counters to a file that can be parsed
with file:consult/1.