From eea5f896780e07f7ca76685061d01e7be5a7abaa Mon Sep 17 00:00:00 2001 From: Lukas Larsson Date: Thu, 11 Sep 2014 18:26:26 +0200 Subject: 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 --- erts/preloaded/src/erlang.erl | 5 ++++- erts/preloaded/src/erts_internal.erl | 7 ++++++- 2 files changed, 10 insertions(+), 2 deletions(-) (limited to 'erts/preloaded') 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(). -- cgit v1.2.3