The following are examples of php_cputime.d. This script traces the on-CPU time of PHP functions and prints a report. Here it traces the example program, Code/Php/func_abc.php. # php_cputime.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 on-CPU times (us), FILE TYPE NAME TOTAL func_abc.php func func_c 17 func_abc.php func func_b 25 func_abc.php func func_a 74 func_abc.php func sleep 93 - total - 210 Inclusive function on-CPU times (us), FILE TYPE NAME TOTAL func_abc.php func func_c 39 func_abc.php func func_b 87 func_abc.php func sleep 93 func_abc.php func func_a 210 In total, six functions were called; sleep was called three times and there was one call each of func_a(), func_b() and func_c(). The exclusive subroutine on-CPU times show that func_a() spent around 74 microseconds on-CPU, func_b() spent 25 microseconds on-CPU, and func_c() spent 17 microseconds on-CPU. This exclusive times excludes time spent in other subroutines. The inclusive subroutine on-CPU times show that func_c() spent around 39 microseconds on-CPU, func_b() spent around 87 microseconds on-CPU and func_a() spent around 210 microseconds. This inclusive time includes the time spent in other functions called (including sleep), and since func_a() called func_b() which called func_c(), these times make perfect sense. These on-CPU times are the time the program spent running on a CPU, from when the function began to when it completed. This does not include time spent off-CPU time such as sleeping for I/O or waiting for scheduling. On-CPU times are useful for showing who is causing the CPUs to be busy. See Notes/ALLoncpu_notes.txt for more details. Also see Notes/ALLexclusive_notes.txt and Notes/ALLinclusive_notes.txt for a detailed explanation of exclusive vs inclusive subroutine time. If you study the func_abc.php program alongside the above output, the numbers should make sense.