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Date: Thu, 27 Nov 2008 11:19:06 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: Frederic Weisbecker <fweisbec@...il.com>
Cc: Ingo Molnar <mingo@...e.hu>, Steven Rostedt <rostedt@...dmis.org>,
Tim Bird <tim.bird@...sony.com>,
Linux Kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] tracing/function-branch-tracer: enhancements for the
trace output
On Thu, 2008-11-27 at 01:46 +0100, Frederic Weisbecker wrote:
> Impact: enhancement
>
> This patch applies some ideas of Ingo Molnar and Steven Rostedt.
>
> * Output leaf functions in one line with parenthesis, semicolon and duration
> output.
>
> * Add a second column (after cpu) for an overhead sign.
> if duration > 100 us, "!"
> if duration > 10 us, "+"
> else " "
>
> * Print output in us with remaining nanosec: u.n
>
> * Print duration on the right end, following the indentation of the functions.
> Use also visual clues: "-" on entry call (no duration to output) and "+" on
> return (duration output).
>
> The name of the tracer has been fixed as well: function-branch becomes
> function_branch.
>
> Here is an example of the new output:
>
> CPU[000] dequeue_entity() { -
> CPU[000] update_curr() { -
> CPU[000] update_min_vruntime(); + 0.512 us
> CPU[000] } + 1.504 us
> CPU[000] clear_buddies(); + 0.481 us
> CPU[000] update_min_vruntime(); + 0.504 us
> CPU[000] } + 4.557 us
> CPU[000] hrtick_update() { -
> CPU[000] hrtick_start_fair(); + 0.489 us
> CPU[000] } + 1.443 us
> CPU[000] + } + 14.655 us
> CPU[000] + } + 15.678 us
> CPU[000] + } + 16.686 us
> CPU[000] msecs_to_jiffies(); + 0.481 us
> CPU[000] put_prev_task_fair(); + 0.504 us
> CPU[000] pick_next_task_fair(); + 0.482 us
> CPU[000] pick_next_task_rt(); + 0.504 us
> CPU[000] pick_next_task_fair(); + 0.481 us
> CPU[000] pick_next_task_idle(); + 0.489 us
> CPU[000] _spin_trylock(); + 0.655 us
> CPU[000] _spin_unlock(); + 0.609 us
>
> CPU[000] ------------8<---------- thread bash-2794 ------------8<----------
>
> CPU[000] finish_task_switch() { -
> CPU[000] _spin_unlock_irq(); + 0.722 us
> CPU[000] } + 2.369 us
> CPU[000] ! } + 501972.605 us
> CPU[000] ! } + 501973.763 us
> CPU[000] copy_from_read_buf() { -
> CPU[000] _spin_lock_irqsave(); + 0.670 us
> CPU[000] _spin_unlock_irqrestore(); + 0.699 us
> CPU[000] copy_to_user() { -
> CPU[000] might_fault() { -
> CPU[000] __might_sleep(); + 0.503 us
> CPU[000] } + 1.632 us
> CPU[000] __copy_to_user_ll(); + 0.542 us
> CPU[000] } + 3.858 us
> CPU[000] tty_audit_add_data() { -
> CPU[000] _spin_lock_irq(); + 0.609 us
> CPU[000] _spin_unlock_irq(); + 0.624 us
> CPU[000] } + 3.196 us
> CPU[000] _spin_lock_irqsave(); + 0.624 us
> CPU[000] _spin_unlock_irqrestore(); + 0.625 us
> CPU[000] + } + 13.611 us
> CPU[000] copy_from_read_buf() { -
> CPU[000] _spin_lock_irqsave(); + 0.624 us
> CPU[000] _spin_unlock_irqrestore(); + 0.616 us
> CPU[000] } + 2.820 us
> CPU[000]
May I suggest putting the times in front of the functions, the times can
be rendered in fixed with, avoiding all this unaligned foobar.
Furthermore, it would be really sweet if ftrace_printk() output would be
at the right indentation level wrt the function it was called from. eg.
CPU[000] - do_sync_read() {
CPU[000] # sock: 0x12345 flag: 1
CPU[000] - sock_aio_read() {
...
CPU[000] + 0.123 }
Where the # line is the ftrace_printk() output.
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