The following is an example of running rb_calltime.d and tracing the elapsed
times for functions.

We run rb_calltime.d while running the program Code/Ruby/func_abc.rb.  We can
see that there are four sections in the DTrace output

# rb_calltime.d
Tracing... Hit Ctrl-C to end.
^C

Count,
   FILE                 TYPE       NAME                                COUNT
   .                    obj-new    NoMemoryError                           1
   .                    obj-new    SystemStackError                        1
   .                    obj-new    ThreadGroup                             1
   .                    obj-new    fatal                                   1
   func_abc.rb          func       Object::func_a                          1
   func_abc.rb          func       Object::func_b                          1
   func_abc.rb          func       Object::func_c                          1
   .                    obj-new    Object                                  3
   func_abc.rb          func       IO::write                               3
   func_abc.rb          func       Module::method_added                    3
   func_abc.rb          func       Object::print                           3
   func_abc.rb          func       Object::sleep                           3
   -                    total      -                                      15

Elapsed times (us),
   FILE                 TYPE       NAME                                TOTAL
   .                    obj-new    SystemStackError                        3
   .                    obj-new    NoMemoryError                           3
   .                    obj-new    fatal                                  11
   .                    obj-new    ThreadGroup                            13
   .                    obj-new    Object                                 26

Exclusive function elapsed times (us),
   FILE                 TYPE       NAME                                TOTAL
   func_abc.rb          func       Module::method_added                    9
   func_abc.rb          func       Object::print                          92
   func_abc.rb          func       IO::write                             185
   func_abc.rb          func       Object::func_c                        344
   func_abc.rb          func       Object::func_a                        379
   func_abc.rb          func       Object::func_b                        383
   func_abc.rb          func       Object::sleep                     3020597
   -                    total      -                                 3021992

Inclusive function elapsed times (us),
   FILE                 TYPE       NAME                                TOTAL
   func_abc.rb          func       Module::method_added                    9
   func_abc.rb          func       IO::write                             185
   func_abc.rb          func       Object::print                         277
   func_abc.rb          func       Object::func_c                    1009829
   func_abc.rb          func       Object::func_b                    2019781
   func_abc.rb          func       Object::sleep                     3020597
   func_abc.rb          func       Object::func_a                    3021983

The first section, Count, shows us how many times each function associated
with func_abc.rb was called.  It also shows other functions called by the Ruby
engine.

The second section, elapsed times, shows how long each action that was not
calling a function took.		

The third section, exclusive function elapsed times, shows us how many 
microseconds the program spends in each function.  This does not include the 
time spent in any sub-functions called by that particular function.  The last 
line gives us the total time in microseconds.

The fourth section, inclusive function elapsed times, are the absolute time
from when the function began to when it completed - which includes off-CPU time 
due to other system events such as I/O, scheduling, interrupts, etc. In 
particular, for this case it has included the time waiting for the sleep 
commands.

Elapsed times are useful for identifying where latencies are.
See Notes/ALLelapsed_notes.txt for more details. Also see
Notes/ALLexclusive_notes.txt and Notes/ALLinclusive_notes.txt for a
detailed explanation of exclusive vs inclusive function time.
