Messages in this thread | | | Date | Tue, 15 Nov 2016 07:42:14 +0100 | From | Ingo Molnar <> | Subject | Re: [PATCHSET 0/7] perf sched: Introduce timehist command, again (v1) |
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* Namhyung Kim <namhyung@kernel.org> wrote:
> Hello, > > This patchset is a rebased version of David's sched timehist work [1]. > I plan to improve perf sched command more and think that having > timehist command before the work looks good. It seems David is busy > these days, so I'm retrying it by myself. > > This implements only basic feature and a few options. I just split > the patch to make it easier to review and did some cosmetic changes. > More patches will come later. > > The below is from the David's original description: > > ------------------------8<------------------------- > 'perf sched timehist' provides an analysis of scheduling events. > > Example usage: > perf sched record -- sleep 1 > perf sched timehist
Cool, very nice!
> By default it shows the individual schedule events, including the time between > sched-in events for the task, the task scheduling delay (time between wakeup > and actually running) and run time for the task: > > time cpu task name[tid/pid] b/n time sch delay run time > ------------- ---- -------------------- --------- --------- --------- > 79371.874569 [11] gcc[31949] 0.014 0.000 1.148 > 79371.874591 [10] gcc[31951] 0.000 0.000 0.024 > 79371.874603 [10] migration/10[59] 3.350 0.004 0.011 > 79371.874604 [11] <idle> 1.148 0.000 0.035 > 79371.874723 [05] <idle> 0.016 0.000 1.383 > 79371.874746 [05] gcc[31949] 0.153 0.078 0.022 > ...
What does the 'b/n' abbreviation stand for? 'Between'? Could we call the column 'sch wait' instead, or so?
> Times are in msec.usec. > > If callchains were recorded they are appended to the line with a default stack depth of 5: > > 79371.874569 [11] gcc[31949] 0.000014 0.000000 0.001148 wait_for_completion_killable do_fork sys_vfork stub_vfork __vfork > 79371.874591 [10] gcc[31951] 0.000000 0.000000 0.000024 __cond_resched _cond_resched wait_for_completion stop_one_cpu sched_exec > 79371.874603 [10] migration/10[59] 0.003350 0.000004 0.000011 smpboot_thread_fn kthread ret_from_fork > 79371.874604 [11] <idle> 0.001148 0.000000 0.000035 cpu_startup_entry start_secondary > 79371.874723 [05] <idle> 0.000016 0.000000 0.001383 cpu_startup_entry start_secondary > 79371.874746 [05] gcc[31949] 0.000153 0.000078 0.000022 do_wait sys_wait4 system_call_fastpath __GI___waitpid
So when I first saw this it was hard for me to disambiguate individual function names. Wouldn't this be a bit more readable:
> 79371.874569 [11] gcc[31949] 0.000014 0.000000 0.001148 wait_for_completion_killable() <- do_fork sys_vfork stub_vfork() <- __vfork() > 79371.874591 [10] gcc[31951] 0.000000 0.000000 0.000024 __cond_resched() <- _cond_resched() <- wait_for_completion() <- stop_one_cpu() <- sched_exec() > 79371.874603 [10] migration/10[59] 0.003350 0.000004 0.000011 smpboot_thread_fn() <- kthread() <- ret_from_fork() > 79371.874604 [11] <idle> 0.001148 0.000000 0.000035 cpu_startup_entry() <- start_secondary() > 79371.874723 [05] <idle> 0.000016 0.000000 0.001383 cpu_startup_entry() <- start_secondary() > 79371.874746 [05] gcc[31949] 0.000153 0.000078 0.000022 do_wait() <- sys_wait4() <- system_call_fastpath() <- __GI___waitpid()
Or:
> 79371.874569 [11] gcc[31949] 0.000014 0.000000 0.001148 wait_for_completion_killable() <- do_fork sys_vfork stub_vfork() <- __vfork() > 79371.874591 [10] gcc[31951] 0.000000 0.000000 0.000024 __cond_resched() <- _cond_resched() <- wait_for_completion() <- stop_one_cpu() <- sched_exec() > 79371.874603 [10] migration/10[59] 0.003350 0.000004 0.000011 smpboot_thread_fn() <- kthread() <- ret_from_fork() > 79371.874604 [11] <idle> 0.001148 0.000000 0.000035 cpu_startup_entry() <- start_secondary() > 79371.874723 [05] <idle> 0.000016 0.000000 0.001383 cpu_startup_entry() <- start_secondary() > 79371.874746 [05] gcc[31949] 0.000153 0.000078 0.000022 do_wait() <- sys_wait4() <- system_call_fastpath() <- __GI___waitpid()
(i.e. visually separate the first entry - and list the rest.)
Or maybe it could be ASCII color coded so that the different entries are easier to separate: for example the functions could be printed in alternating white/grey color?
Thanks,
Ingo
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