Re: [PATCH] Add function graph tracer support for ARM

[Tim Bird <tim.bird@am.sony.com>]

Frederic Weisbecker wrote:
> On Thu, Apr 23, 2009 at 02:49:56PM -0700, Tim Bird wrote:
>> Uwe � wrote:
>>>> Signed-off-by: <tim.bird@am.sony.com>
>>> According to Documentation/SubmittingPatches you need to provide your
>>> real name in the S-o-b line.
>> OK -that's embarrassing - I'll fix this.
>> scripts/checkpatch.pl didn't catch this.  I may look at adding
>> something to checkpatch.pl to catch empty names.
>>
>>> For the lazy of us, can you point me^Uus to some documentation how to
>>> use the graph tracer?
>> It looks like Documentation/ftrace.txt is missing anything about
>> function graph tracing.
>>
>> Should I add a section?
> 
> 
> 
> There is already a section in Documentation/frace.txt as well in 2.6.30 :-)

LOL. :-)

> Oh, that's the first function graph trace from Arm I can see.
> /me feels a bit moved...
> 
> Just one childish caprice...it would be nice to see a part of a
> trace which shows specific Arm arch functions in the next changelog :-)

Will do.  Here's something to tide you over.  I have pages and
pages of the following (repeating over and over):

 0)               |  omap_pm_idle() {
 0) + 30.518 us   |    omap_dma_running();
 0)               |    __exception_text_start() {
 0)               |      irq_enter() {
 0)   0.000 us    |        idle_cpu();
 0)   0.000 us    |      }
 0)   0.000 us    |      irq_to_desc();
 0)               |      handle_level_irq() {
 0) + 30.517 us   |        omap_mask_irq();
 0)               |        omap_mask_ack_irq() {
 0)   0.000 us    |          omap_mask_irq();
 0) + 30.518 us   |        }
 0)               |        handle_IRQ_event() {
 0)               |          omap_mpu_timer1_interrupt() {
 0)               |            tick_handle_periodic() {
 0)               |              tick_periodic() {
 0)               |                do_timer() {
 0)               |                  update_wall_time() {
 0)   0.000 us    |                    mpu_read();
 0)   0.000 us    |                    update_xtime_cache();
 0) + 30.517 us   |                    clocksource_get_next();
 0) ! 122.070 us  |                  }
 0) ! 183.106 us  |                }
 0)               |                update_process_times() {
 0)               |                  account_process_tick() {
 0) + 30.517 us   |                    account_idle_time();
 0) + 30.517 us   |                  }
 0)               |                  run_local_timers() {
 0)               |                    hrtimer_run_queues() {
 0)   0.000 us    |                      current_kernel_time();
 0) + 30.518 us   |                    }
 0)   0.000 us    |                    raise_softirq();
 0)               |                    softlockup_tick() {
 0)               |                      get_timestamp() {
 0)   0.000 us    |                        sched_clock();
 0)   0.000 us    |                      }
 0) + 61.035 us   |                    }
 0) ! 122.071 us  |                  }
 0)               |                  rcu_pending() {
 0)   0.000 us    |                    __rcu_pending();
 0)   0.000 us    |                    __rcu_pending();
 0) + 61.035 us   |                  }
 0)   0.000 us    |                  printk_tick();
 0)               |                  scheduler_tick() {
 0)   0.000 us    |                    sched_clock();
 0) + 30.518 us   |                    task_tick_idle();
 0) + 61.035 us   |                  }
 0)   0.000 us    |                  run_posix_cpu_timers();
 0) ! 305.176 us  |                }
 0)   0.000 us    |                profile_tick();
 0) ! 518.799 us  |              }
 0) ! 518.799 us  |            }
 0) ! 549.316 us  |          }
 0) ! 549.316 us  |        }
 0)   0.000 us    |        note_interrupt();
 0)   0.000 us    |        omap_unmask_irq();
 0) ! 671.386 us  |      }
 0)               |      irq_exit() {
 0)               |        __do_softirq() {
 0)               |          run_timer_softirq() {
 0)   0.000 us    |            hrtimer_run_pending();
 0) + 30.518 us   |          }
 0)   0.000 us    |          _local_bh_enable();
 0) + 61.036 us   |        }
 0) + 91.553 us   |      }
 0) ! 823.975 us  |    }
 0) ! 9979.248 us |  }

Enjoy :-)
 -- Tim

=============================
Tim Bird
Architecture Group Chair, CE Linux Forum
Senior Staff Engineer, Sony Corporation of America
=============================