Module Core_profiler.Std_offline

module Profiler_units = Core_profiler_disabled.Profiler_units

Open this Std for offline use of probes.

include Offline

Running a program with offline metrics collection causes it to write out a data file on exit. This data file is typically called profiler.dat. The collected metrics can then be analyzed using profiler-tool.exe.

I don't trust these numbers, but here they are: 

    ┌──────────────────────────────────────────────────────┬──────────┬────────────┐
    │ Name                                                 │ Time/Run │ Percentage │
    ├──────────────────────────────────────────────────────┼──────────┼────────────┤
    │ [offline.ml:Timer] at                                │  18.29ns │     10.34% │
    │ [offline.ml:Probe] at                                │  21.92ns │     12.38% │
    │ [offline.ml:Delta_timer] start_async                 │  10.94ns │      6.18% │
    │ [offline.ml:Delta_timer] stop_async                  │  22.78ns │     12.87% │
    │ [offline.ml:Delta_timer] start                       │  11.23ns │      6.34% │
    │ [offline.ml:Delta_timer] stop                        │  22.84ns │     12.91% │
    │ [offline.ml:Delta_timer.wrap_sync] nop               │   2.45ns │      1.38% │
    │ [offline.ml:Delta_timer.wrap_sync] wrapped_nop       │  40.59ns │     22.93% │
    │ [offline.ml:Delta_timer.wrap_sync] count_256         │ 143.57ns │     81.12% │
    │ [offline.ml:Delta_timer.wrap_sync] wrapped_count_256 │ 176.99ns │    100.00% │
    │ [offline.ml:Delta_probe] start                       │   2.47ns │      1.40% │
    │ [offline.ml:Delta_probe] stop                        │  22.11ns │     12.49% │
    │ [offline.ml:Delta_probe] start_async                 │   2.44ns │      1.38% │
    │ [offline.ml:Delta_probe] stop_async                  │  22.20ns │     12.54% │
    └──────────────────────────────────────────────────────┴──────────┴────────────┘

In Offline, a Delta_probe differs from a two point Group in that for each start/stop pair, only one message is written to the buffer. This means that only the delta in the probe is available, as opposed to deltas in both probe and time.

module Profiler : sig ... end
module Timer : Core_profiler_disabled.Intf.Probe with type a create_args := a Core_profiler_disabled.Intf.timer_create_args and type a record_args := a Core_profiler_disabled.Intf.timer_record_args and type t = private int

A Timer contains only a time stamp and no extra information; however, it is useful because (in Offline) the current time is recorded when measurements are made.

module Probe : Core_profiler_disabled.Intf.Probe with type a create_args := a Core_profiler_disabled.Intf.probe_create_args and type a record_args := a Core_profiler_disabled.Intf.probe_record_args and type t = private int

A Probe records some integer value that is passed to at along with a timestamp.

module Delta_probe : sig ... end with type state = private int

Delta_probe is an optimized two-probe group to track changes to some counter.

module Delta_timer : sig ... end with type state = private Core.Time_ns.t

Delta_timer is an optimized two-probe group to track time differences between calls to start and stop.