scheduler(3)

scheduler(3erl)            Erlang Module Definition            scheduler(3erl)

NAME
       scheduler - Measure scheduler utilization

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

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

DATA TYPES
       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.

EXPORTS
       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, in-
              cluding 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:uti-
              lization(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.

Ericsson AB                   runtime_tools 1.15               scheduler(3erl)