DOKK / manpages / debian 11 / erlang-manpages / scheduler.3erl.en
scheduler(3erl) Erlang Module Definition scheduler(3erl)

scheduler - Measure scheduler utilization

This module contains utility functions for easier measurement and calculation of scheduler utilization, otherwise obtained from calling the more primitive statistics(scheduler_wall_time).

The simplest usage is to call scheduler:utilization(Seconds).

sched_sample()



sched_type() = normal | cpu | io



sched_id() = integer()



sched_util_result() = 


    [{sched_type(), sched_id(), float(), string()} |


     {total, float(), string()} |


     {weighted, float(), string()}]

A list of tuples containing results for individual schedulers as well as aggregated averages. Util is the scheduler utilization as a floating point value between 0.0 and 1.0. Percent is the same utilization as a more human readable string expressed in percent.

{normal, SchedulerId, Util, Percent}:
Scheduler utilization of a normal scheduler with number SchedulerId.
{cpu, SchedulerId, Util, Percent}:
Scheduler utilization of a dirty-cpu scheduler with number SchedulerId.
{io, SchedulerId, Util, Percent}:
Scheduler utilization of a dirty-io scheduler with number SchedulerId. This tuple will only exist if both samples were taken with sample_all/0.
{total, Util, Percent}:
Total utilization of all normal and dirty-cpu schedulers.
{weighted, Util, Percent}:
Total utilization of all normal and dirty-cpu schedulers, weighted against maximum amount of available CPU time.


sample() -> sched_sample()

Return a scheduler utilization sample for normal and dirty-cpu schedulers.


sample_all() -> sched_sample()

Return a scheduler utilization sample for all schedulers, including dirty-io schedulers.


utilization(Seconds) -> sched_util_result()

Types:

Seconds = integer() >= 1

Measure utilization for normal and dirty-cpu schedulers during Seconds seconds, and then return the result.


utilization(Sample) -> sched_util_result()

Types:

Sample = sched_sample()

Calculate scheduler utilizations for the time interval from when Sample was taken and "now". The same as calling scheduler:utilization(Sample, scheduler:sample_all()).


utilization(Sample1, Sample2) -> sched_util_result()

Types:

Sample1 = Sample2 = sched_sample()

Calculates scheduler utilizations for the time interval between the two samples obtained from calling sample/0 or sample_all/0.

runtime_tools 1.15.1 Ericsson AB