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authorLukas Larsson <[email protected]>2014-09-12 16:38:00 +0200
committerLukas Larsson <[email protected]>2016-02-02 10:45:21 +0100
commit664ed2a6fd2b324bb6b56db3d3eca853cfda8f61 (patch)
tree286743a4b1f794948329961e7f5879b5f54f54a5 /erts/emulator/test
parenteea5f896780e07f7ca76685061d01e7be5a7abaa (diff)
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erts: Add microstate accounting
Microstate accounting is a way to track which state the different threads within ERTS are in. The main usage area is to pin point performance bottlenecks by checking which states the threads are in and then from there figuring out why and where to optimize. Since checking whether microstate accounting is on or off is relatively expensive if done in a short loop only a few of the states are enabled by default and more states can be enabled through configure. I've done some benchmarking and the overhead with it turned off is not noticible and with it on it is a fraction of a percent. If you enable the extra states, depending on the benchmark, the ovehead when turned off is about 1% and when turned on somewhere inbetween 5-15%. OTP-12345
Diffstat (limited to 'erts/emulator/test')
-rw-r--r--erts/emulator/test/statistics_SUITE.erl95
1 files changed, 93 insertions, 2 deletions
diff --git a/erts/emulator/test/statistics_SUITE.erl b/erts/emulator/test/statistics_SUITE.erl
index 53c9ba8715..a1b63716a9 100644
--- a/erts/emulator/test/statistics_SUITE.erl
+++ b/erts/emulator/test/statistics_SUITE.erl
@@ -32,7 +32,7 @@
run_queue_one/1,
scheduler_wall_time/1,
reductions/1, reductions_big/1, garbage_collection/1, io/1,
- badarg/1, run_queues_lengths_active_tasks/1]).
+ badarg/1, run_queues_lengths_active_tasks/1, msacc/1]).
%% Internal exports.
@@ -55,7 +55,8 @@ all() ->
[{group, wall_clock}, {group, runtime}, reductions,
reductions_big, {group, run_queue}, scheduler_wall_time,
garbage_collection, io, badarg,
- run_queues_lengths_active_tasks].
+ run_queues_lengths_active_tasks,
+ msacc].
groups() ->
[{wall_clock, [],
@@ -466,3 +467,93 @@ run_queues_lengths_active_tasks(Config) ->
TokLoops),
ok.
+
+msacc(doc) ->
+ "Tests that statistics(microstate_statistics) works.";
+msacc(Config) ->
+
+ %% Test if crypto nif is available
+ Niff = try crypto:strong_rand_bytes(1), ok catch _:_ -> nok end,
+ TmpFile = filename:join(proplists:get_value(priv_dir,Config),"file.tmp"),
+
+ false = erlang:system_flag(microstate_accounting, true),
+
+ msacc_test(TmpFile),
+
+ true = erlang:system_flag(microstate_accounting, false),
+
+ %% Make sure that all states were triggered at least once
+ maps:map(fun(nif, 0) ->
+ case Niff of
+ ok ->
+ ct:fail({zero_state,nif});
+ nok ->
+ ok
+ end;
+ (aux, 0) ->
+ %% aux will be zero if we do not have smp support
+ %% or no async threads
+ case erlang:system_info(smp_support) orelse
+ erlang:system_info(thread_pool_size) > 0 of
+ false ->
+ ok;
+ true ->
+ ct:log("msacc: ~p",[erlang:statistics(microstate_accounting)]),
+ ct:fail({zero_state,aux})
+ end;
+ (Key, 0) ->
+ ct:log("msacc: ~p",[erlang:statistics(microstate_accounting)]),
+ ct:fail({zero_state,Key});
+ (_,_) -> ok
+ end,msacc_sum_states()),
+
+ erlang:system_flag(microstate_accounting, reset),
+
+ msacc_test(TmpFile),
+
+ %% Make sure all counters are zero after stopping and resetting
+ maps:map(fun(_Key, 0) -> ok;
+ (Key,_) ->
+ ct:log("msacc: ~p",[erlang:statistics(microstate_accounting)]),
+ ct:fail({non_zero_state,Key})
+ end,msacc_sum_states()).
+
+%% This test tries to make sure to trigger all of the different available states
+msacc_test(TmpFile) ->
+
+ %% We write some data
+ [file:write_file(TmpFile,<<0:(1024*1024*8)>>,[raw]) || _ <- lists:seq(1,100)],
+
+ %% Do some ETS operations
+ Tid = ets:new(table, []),
+ ets:insert(Tid, {1, hello}),
+ ets:delete(Tid),
+
+ %% Collect some garbage
+ [erlang:garbage_collect() || _ <- lists:seq(1,100)],
+
+ %% Send some messages
+ [begin self() ! {hello},receive _ -> ok end end || _ <- lists:seq(1,100)],
+
+ %% Setup some timers
+ Refs = [erlang:send_after(10000,self(),ok) || _ <- lists:seq(1,100)],
+
+ %% Do some nif work
+ catch [crypto:strong_rand_bytes(128) || _ <- lists:seq(1,100)],
+
+ %% Cancel some timers
+ [erlang:cancel_timer(R) || R <- Refs],
+
+ %% Wait for a while
+ timer:sleep(100).
+
+msacc_sum_states() ->
+ Stats = erlang:statistics(microstate_accounting),
+ [#{ counters := C }|_] = Stats,
+ InitialCounters = maps:map(fun(_,_) -> 0 end,C),
+ lists:foldl(fun(#{ counters := Counters }, Cnt) ->
+ maps:fold(fun(Key, Value, Acc) ->
+ NewValue = Value+maps:get(Key,Acc),
+ maps:update(Key, NewValue, Acc)
+ end, Cnt, Counters)
+ end,InitialCounters,Stats).