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Diffstat (limited to 'lib/runtime_tools/doc/src/scheduler.xml')
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diff --git a/lib/runtime_tools/doc/src/scheduler.xml b/lib/runtime_tools/doc/src/scheduler.xml new file mode 100644 index 0000000000..b033430183 --- /dev/null +++ b/lib/runtime_tools/doc/src/scheduler.xml @@ -0,0 +1,135 @@ +<?xml version="1.0" encoding="utf-8" ?> +<!DOCTYPE erlref SYSTEM "erlref.dtd"> + +<erlref> + <header> + <copyright> + <year>2018</year> + <holder>Ericsson AB. All Rights Reserved.</holder> + </copyright> + <legalnotice> + Licensed under the Apache License, Version 2.0 (the "License"); + you may not use this file except in compliance with the License. + You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, software + distributed under the License is distributed on an "AS IS" BASIS, + WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + See the License for the specific language governing permissions and + limitations under the License. + + </legalnotice> + + <title></title> + <prepared></prepared> + <responsible></responsible> + <docno>1</docno> + <approved></approved> + <checked></checked> + <date></date> + <rev></rev> + <file>scheduler.xml</file> + </header> + <module since="OTP 21.0">scheduler</module> + <modulesummary>Measure scheduler utilization</modulesummary> + <description> + <p>This module contains utility functions for easier measurement and + calculation of scheduler utilization, otherwise obtained from calling the + more primitive <seealso marker="erts:erlang#statistics_scheduler_wall_time"> + <c>statistics(scheduler_wall_time)</c></seealso>.</p> + <p>The simplest usage is to call <seealso marker="#utilization-1"> + <c>scheduler:utilization(Seconds)</c></seealso>.</p> + </description> + + <datatypes> + <datatype> + <name name="sched_sample"/> + </datatype> + <datatype> + <name name="sched_type"/> + </datatype> + <datatype> + <name name="sched_id"/> + </datatype> + <datatype> + <name name="sched_util_result"/> + <desc> + <p>A list of tuples containing results for individual schedulers + as well as aggregated averages. <c>Util</c> is the scheduler utilization + as a floating point value between 0.0 and 1.0. <c>Percent</c> is the + same utilization as a more human readable string expressed in percent.</p> + <taglist> + <tag><c>{normal, SchedulerId, Util, Percent}</c></tag> + <item>Scheduler utilization of a normal scheduler with number + <c>SchedulerId</c>.</item> + <tag><c>{cpu, SchedulerId, Util, Percent}</c></tag> + <item>Scheduler utilization of a dirty-cpu scheduler with number + <c>SchedulerId</c>.</item> + <tag><c>{io, SchedulerId, Util, Percent}</c></tag> + <item>Scheduler utilization of a dirty-io scheduler with number + <c>SchedulerId</c>. This tuple will only exist if both samples were + taken with <seealso marker="#sample_all-0"><c>sample_all/0</c></seealso>.</item> + <tag><c>{total, Util, Percent}</c></tag> + <item>Total utilization of all normal and dirty-cpu schedulers.</item> + <tag><c>{weighted, Util, Percent}</c></tag> + <item>Total utilization of all normal and dirty-cpu schedulers, + weighted against maximum amount of available CPU time.</item> + </taglist> + </desc> + </datatype> + </datatypes> + + <funcs> + + <func> + <name name="sample" arity="0" since="OTP 21.0"/> + <fsummary>Get scheduler utilization sample.</fsummary> + <desc> + <p>Return a scheduler utilization sample for normal and dirty-cpu + schedulers.</p> + </desc> + </func> + + <func> + <name name="sample_all" arity="0" since="OTP 21.0"/> + <fsummary>Get scheduler utilization sample.</fsummary> + <desc> + <p>Return a scheduler utilization sample for all schedulers, + including dirty-io schedulers.</p> + </desc> + </func> + + <func> + <name name="utilization" arity="1" clause_i="1" since="OTP 21.0"/> + <fsummary>Measure scheduler utilizations during a period of time.</fsummary> + <desc> + <p>Measure utilization for normal and dirty-cpu schedulers during + <c><anno>Seconds</anno></c> seconds, and then return the result.</p> + </desc> + </func> + + <func> + <name name="utilization" arity="1" clause_i="2" since="OTP 21.0"/> + <fsummary>Measure scheduler utilizations since sample.</fsummary> + <desc> + <p>Calculate scheduler utilizations for the time interval from when + <c><anno>Sample</anno></c> was taken and "now". The same as calling + <c>scheduler:utilization(Sample, scheduler:sample_all())</c>.</p> + </desc> + </func> + + <func> + <name name="utilization" arity="2" since="OTP 21.0"/> + <fsummary>Measure scheduler utilizations between two samples.</fsummary> + <desc> + <p>Calculates scheduler utilizations for the time interval between + the two samples obtained from calling + <seealso marker="#sample-0"><c>sample/0</c></seealso> or + <seealso marker="#sample_all-0"><c>sample_all/0</c></seealso>.</p> + </desc> + </func> + + </funcs> + </erlref> |