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authorLukas Larsson <[email protected]>2014-09-11 18:26:26 +0200
committerLukas Larsson <[email protected]>2016-02-02 10:45:21 +0100
commiteea5f896780e07f7ca76685061d01e7be5a7abaa (patch)
tree7d4a852b20f2075637457052844865e1c56b1e21 /erts/preloaded
parentd76ee58c07f32dfc0652844ec2b513af2105ffa1 (diff)
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erts, kernel: Add os:perf_counter function
The perf_counter is a very very cheap and high resolution timer that can be used to timestamp system events. It does not have monoticity guarantees, but should on most OS's expose a monotonous time. A special instruction has been created for this counter to further speed up fetching it. OTP-12908
Diffstat (limited to 'erts/preloaded')
-rw-r--r--erts/preloaded/src/erlang.erl5
-rw-r--r--erts/preloaded/src/erts_internal.erl7
2 files changed, 10 insertions, 2 deletions
diff --git a/erts/preloaded/src/erlang.erl b/erts/preloaded/src/erlang.erl
index bca366681d..6f56a81eec 100644
--- a/erts/preloaded/src/erlang.erl
+++ b/erts/preloaded/src/erlang.erl
@@ -71,7 +71,8 @@
| 'milli_seconds'
| 'micro_seconds'
| 'nano_seconds'
- | 'native'.
+ | 'native'
+ | 'perf_counter'.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% Native code BIF stubs and their types
@@ -1347,6 +1348,7 @@ convert_time_unit(Time, FromUnit, ToUnit) ->
try
FU = case FromUnit of
native -> erts_internal:time_unit();
+ perf_counter -> erts_internal:perf_counter_unit();
nano_seconds -> 1000*1000*1000;
micro_seconds -> 1000*1000;
milli_seconds -> 1000;
@@ -1355,6 +1357,7 @@ convert_time_unit(Time, FromUnit, ToUnit) ->
end,
TU = case ToUnit of
native -> erts_internal:time_unit();
+ perf_counter -> erts_internal:perf_counter_unit();
nano_seconds -> 1000*1000*1000;
micro_seconds -> 1000*1000;
milli_seconds -> 1000;
diff --git a/erts/preloaded/src/erts_internal.erl b/erts/preloaded/src/erts_internal.erl
index 84dedab930..c3a14d272d 100644
--- a/erts/preloaded/src/erts_internal.erl
+++ b/erts/preloaded/src/erts_internal.erl
@@ -45,7 +45,7 @@
-export([await_result/1, gather_io_bytes/2]).
--export([time_unit/0]).
+-export([time_unit/0, perf_counter_unit/0]).
-export([is_system_process/1]).
@@ -345,6 +345,11 @@ flush_monitor_messages(Ref, Multi, Res) when is_reference(Ref) ->
time_unit() ->
erlang:nif_error(undefined).
+-spec erts_internal:perf_counter_unit() -> pos_integer().
+
+perf_counter_unit() ->
+ erlang:nif_error(undefined).
+
-spec erts_internal:is_system_process(Pid) -> boolean() when
Pid :: pid().