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author | Sverker Eriksson <sverker@erlang.org> | 2022-01-11 23:14:21 +0100 |
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committer | Sverker Eriksson <sverker@erlang.org> | 2022-01-11 23:14:21 +0100 |
commit | 70a36dc442feda69eef375a7ffb15d4a7fb98269 (patch) | |
tree | 430e816276ba7b266c377da10a7f1a8d4c6560e0 /erts/doc/src/erlang.xml | |
parent | f518b5d3a9bde82ebcd16697f01ed2fd1fcfd0cb (diff) | |
parent | d33bb24ef66be325282fc75bee00dec066e6c11c (diff) | |
download | erlang-70a36dc442feda69eef375a7ffb15d4a7fb98269.tar.gz |
Merge branch 'maint'
Diffstat (limited to 'erts/doc/src/erlang.xml')
-rw-r--r-- | erts/doc/src/erlang.xml | 34 |
1 files changed, 30 insertions, 4 deletions
diff --git a/erts/doc/src/erlang.xml b/erts/doc/src/erlang.xml index bc79442c3a..8a2ecd0cb9 100644 --- a/erts/doc/src/erlang.xml +++ b/erts/doc/src/erlang.xml @@ -9432,10 +9432,36 @@ ok <fsummary>Set system flag scheduler_wall_time.</fsummary> <desc> <p> - Turns on or off scheduler wall time measurements.</p> - <p>For more information, see - <seeerl marker="#statistics_scheduler_wall_time"> - <c>statistics(scheduler_wall_time)</c></seeerl>.</p> + Try enable or disable scheduler wall time measurements by passing + <c><anno>Boolean</anno></c> as either <c>true</c> or <c>false</c>. + </p> + <p> + For more information about how to use scheduler wall time + measurements, see <seeerl marker="#statistics_scheduler_wall_time"> + <c>statistics(scheduler_wall_time)</c></seeerl>. + </p> + <p> + Scheduler wall time measurements has a node global state. It is either + enabled for all processes on the node or disabled for all + processes. Each process has a logical counter initialized as zero. A + call with <c><anno>Boolean</anno></c> as <c>true</c> will increase + that counter one step for the calling process. A call with + <c>false</c> will decrease it one step unless it already is + zero. The node global state for <c>scheduler_wall_time</c> will be + enabled as long as there is at least one process alive with a counter + value larger than zero. When a process terminates, its counter will + also disappear. To ensure <c>scheduler_wall_time</c> is kept enabled, + the process that enabled it must therefore be kept alive. + </p> + <p> + Returns the old value of the node global state, <c>true</c> if + scheduler wall time measurements were enabled, <c>false</c> + if it were disabled. + </p> + <p> + Scheduler wall time measurements do consume some cpu overhead and + should not be left turned on unless used. + </p> </desc> </func> |