Training courses

Kernel and Embedded Linux

Bootlin training courses

Embedded Linux, kernel,
Yocto Project, Buildroot, real-time,
graphics, boot time, debugging...

Bootlin logo

Elixir Cross Referencer

Following are examples of running tcl_cputime.d.

Here it runs while we execute Code/Tcl/func_slow.tcl

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

Top 10 counts,
      PID TYPE       NAME                                                COUNT
    16038 cmd        set                                                     2
    16038 cmd        namespace                                               3
    16038 cmd        puts                                                    3
    16038 cmd        lappend                                                 4
    16038 cmd        lsearch                                                 4
    16038 cmd        if                                                      8
    16038 cmd        info                                                   11
    16038 cmd        file                                                   12
    16038 cmd        proc                                                   12
        0 total      -                                                      82

Top 10 exclusive on-CPU times (us),
      PID TYPE       NAME                                                TOTAL
    16038 cmd        namespace                                             130
    16038 cmd        puts                                                  232
    16038 cmd        if                                                    310
    16038 cmd        tclInit                                               315
    16038 cmd        file                                                  411
    16038 cmd        source                                                760
    16038 proc       func_a                                             535521
    16038 proc       func_b                                            1071082
    16038 proc       func_c                                            1619323
        0 total      -                                                 3228670

Top 10 inclusive on-CPU times (us),
      PID TYPE       NAME                                                TOTAL
    16038 cmd        source                                               1359
    16038 cmd        uplevel                                              1367
    16038 proc       tclInit                                              1865
    16038 cmd        tclInit                                              2180
    16038 proc       func_c                                            1619360
    16038 cmd        func_c                                            1619404
    16038 proc       func_b                                            2690525
    16038 cmd        func_b                                            2690568
    16038 proc       func_a                                            3226247
    16038 cmd        func_a                                            3226275

We can see that the output is in three sections.  The first section represents
the ten most commonly executed commands while the script is tracing.

The exclusive function on-CPU times show that func_a spent around 0.5 seconds
on-CPU, func_b spent about 1.0 seconds, and func_c, 1.6 seconds. This excludes
time spent in other procedures or commands.

The inclusive function on-CPU times show the time spent by these procedures in
total, including the time spent in other functions called, and since func_a
called func_b which called func_c, these times make sense.

These on-CPU times are the time the thread 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 function time.