First stab at documenting Telemetry::Instrument::Usage

Author: lizmat

doc/Type/Telemetry/Instrument/Usage.pod6

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+
+=begin pod
+
+=TITLE class Telemetry::Instrument::Usage
+
+=SUBTITLE Instrument for collecting getrusage data
+
+    class Telemetry::Instrument::Usage { }
+
+B<Note: > This class is a Rakudo-specific feature and not standard Perl 6.
+
+Objects of this class are generally not created by themselves, but rather
+through making a L<snap|/type/Telemetry>shot.
+
+=head2 Useful readings
+
+This class provides the following generally usable readings (in alphabetical
+order):
+
+=item cpu
+
+The total amount of CPU time (in microseconds), essentially the sum of
+C<cpu-user> and C<cpu-sys>.
+
+=item cpu-sys
+
+The number of microseconds of CPU used by the system.
+
+=item cpu-user
+
+The number of microseconds of CPU used by the user program.
+
+=item cpus
+
+The number of CPU's active, essentially C<cpu> divided by C<wallclock>.
+
+=item max-rss
+
+The maximum resident set size (in KiB).
+
+=item util%
+
+Percentage of CPU utilization, essentially 100 * C<cpus> / number of CPU cores.
+
+=item wallclock
+
+The time the program has been executing (in microseconds).
+
+=head Less useful readings
+
+The following readings may or may not contain sensible information, mostly
+depending on hardware and OS being used.  Please check your local C<getrusage>
+documentation for their exact meaning:
+
+  name        getrusage struct name
+  ====        =====================
+  max-rss     ru_maxrss
+  ix-rss      ru_ixress
+  id-rss      ru_idrss
+  is-rss      ru_isrss
+  minf        ru_minflt
+  majf        ru_majflt
+  nswp        ru_nswap
+  inb         ru_inblock
+  outb        ru_oublock
+  msnd        ru_msgsnd
+  mrcv        ru_msgrcv
+  nsig        ru_nsignals
+  volcsw      ru_nvcsw
+  invcsw      ru_nivcsw
+
+=end pod
+
+# vim: expandtab softtabstop=4 shiftwidth=4 ft=perl6