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Subject: Re: [PATCH] tracing/function-graph-tracer: adjustments of the
 trace informations
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: =?ISO-8859-1?Q?Fr=E9d=E9ric?= Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>, Steven Rostedt <rostedt@goodmis.org>,
       Tim Bird <tim.bird@am.sony.com>,
       Linux Kernel <linux-kernel@vger.kernel.org>
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Date: Sat, 29 Nov 2008 11:59:29 +0100
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On Sat, 2008-11-29 at 04:40 +0100, Frédéric Weisbecker wrote:
> 2008/11/28 Ingo Molnar <mingo@elte.hu>:

> I tried to figure out a way to signal a hardirq in a trace, I like
> this arrow but It
> breaks the indentation.
> I would suggest:
> 
>   0)               |              skb_dequeue() {
>   0)      0.365 us |                _spin_lock_irqsave();
>   0)      0.422 us |                _spin_unlock_irqrestore();
>   0)      1.912 us |              }
>   0)               |              memcpy_toiovec() {
>   0)               |                copy_to_user() {
>              =====>
>   0)               |               smp_apic_timer_interrupt() {
>   0)      0.450 us |                    native_apic_mem_write();
>   0)               |                    irq_enter() {
>   0)      0.410 us |                      idle_cpu();
>   0)      1.167 us |                    }
>   0)               |                    hrtimer_interrupt() {
> 
> Your idea solves a part of one of the features I wanted to add: why
> not using a single character column to print
> the current context: workqueue, syscall, kernel thread, tasklet, hardirq .....

That was my initial suggestion too, like the latency tracer has.

Then again, most of that would be obvious from the comm/pid column, that
will show preemption and all those things.

But showing Hard,Soft irq disabled and perhaps the preempt count would
be handy.