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+The following is an example of running php_calltime.d and tracing the elapsed
+times for functions.
+
+We run php_calltime.d while running the program Code/Php/func_abc.php.  We can
+see that there are three sections in the DTrace output
+
+# php_calltime.d
+Tracing... Hit Ctrl-C to end.
+^C
+
+Count,
+   FILE                 TYPE       NAME                                COUNT
+   func_abc.php         func       func_a                                  1
+   func_abc.php         func       func_b                                  1
+   func_abc.php         func       func_c                                  1
+   func_abc.php         func       sleep                                   3
+   -                    total      -                                       6
+
+Exclusive function elapsed times (us),
+   FILE                 TYPE       NAME                                TOTAL
+   func_abc.php         func       func_c                                330
+   func_abc.php         func       func_b                                367
+   func_abc.php         func       func_a                                418
+   func_abc.php         func       sleep                             3025644
+   -                    total      -                                 3026761
+
+Inclusive function elapsed times (us),
+   FILE                 TYPE       NAME                                TOTAL
+   func_abc.php         func       func_c                            1010119
+   func_abc.php         func       func_b                            2020118
+   func_abc.php         func       sleep                             3025644
+   func_abc.php         func       func_a                            3026761
+
+Section 1 - Count shows us how many times each function was called in the
+Code/Php/func_abc.php program, with the last line giving us a total number of
+functions called (in this case, six).
+
+Section 2 - These 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.  Again the last line gives
+us the total time in microseconds.
+
+Section 3 - These 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.