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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 /lib/kernel/doc/src
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 'lib/kernel/doc/src')
-rw-r--r--lib/kernel/doc/src/os.xml25
1 files changed, 25 insertions, 0 deletions
diff --git a/lib/kernel/doc/src/os.xml b/lib/kernel/doc/src/os.xml
index 682d4a2eac..165160a909 100644
--- a/lib/kernel/doc/src/os.xml
+++ b/lib/kernel/doc/src/os.xml
@@ -37,6 +37,7 @@
use these functions can be of help in enabling a program to run on
most platforms.</p>
</description>
+
<funcs>
<func>
<name name="cmd" arity="1"/>
@@ -210,6 +211,30 @@ format_utc_timestamp() ->
</desc>
</func>
<func>
+ <name name="perf_counter" arity="0"/>
+ <fsummary>Returns a performance counter</fsummary>
+ <desc>
+ <p>Returns the current performance counter value in <c>perf_counter</c>
+ <seealso marker="erts:erlang#type_time_unit">time unit</seealso>.
+ This is a highly optimized call that might not be traceable.
+ </p>
+ </desc>
+ </func>
+ <func>
+ <name name="perf_counter" arity="1"/>
+ <fsummary>Returns a performance counter</fsummary>
+ <desc><p>Returns a performance counter that can be used as a very fast and
+ high resolution timestamp. This counter is read directly from the hardware or operating
+ system with the same guarantees. This means that two consecutive calls
+ to the function are not guaranteed to be monotonic, though it most likely will be.
+ The performance counter till be converted to the resolution passed as an argument.</p>
+ <pre>1> <input>T1 = os:perf_counter(1000),receive after 10000 -> ok end,T2 = os:perf_counter(1000).</input>
+176525861
+2> <input>T2 - T1.</input>
+10004</pre>
+ </desc>
+ </func>
+ <func>
<name name="type" arity="0"/>
<fsummary>Return the OS family and, in some cases, OS name of the current operating system</fsummary>
<desc>