linux-kernel - Re: [PATCH 2/2] tracing/fastboot: Use the ring-buffer timestamp for initcall entries

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Date:	Wed, 12 Nov 2008 11:58:24 +0100
From:	"Frédéric Weisbecker" <fweisbec@...il.com>
To:	"Ingo Molnar" <mingo@...e.hu>
Cc:	"Steven Rostedt" <rostedt@...dmis.org>,
	"Linux Kernel" <linux-kernel@...r.kernel.org>,
	"Arjan van de Ven" <arjan@...radead.org>
Subject: Re: [PATCH 2/2] tracing/fastboot: Use the ring-buffer timestamp for initcall entries

2008/11/12 Ingo Molnar <mingo@...e.hu>:
>
> * Frederic Weisbecker <fweisbec@...il.com> wrote:
>
>> Impact: Split the boot tracer entries in two parts: call and return
>>
>> Now that we are using the sched tracer from the boot tracer, we want
>> to use the same timestamp than the ring-buffer to have consistent
>> time captures between sched events and initcall events. So we get
>> rid of the old time capture by the boot tracer and split the
>> initcall events in two parts: call and return. This way we have the
>> ring buffer timestamp of both.
>>
>> There is an example of a trace in attachment.
>>
>> Signed-off-by: Frederic Weisbecker <fweisbec@...il.com>
>> ---
>>  include/trace/boot.h      |   31 ++++++++---
>>  init/main.c               |   32 ++++++------
>>  kernel/trace/trace.h      |   17 ++++--
>>  kernel/trace/trace_boot.c |  123 ++++++++++++++++++++++++++++++++++-----------
>>  4 files changed, 144 insertions(+), 59 deletions(-)
>
> applied to tip/tracing/fastboot, thanks Frederic!
>
> one small detail, do we need these messages in the boot tracer:
>
>  ##### CPU 1 buffer started ####
>
> they are helpful for latency traces but might be confusing for boot
> traces. (they lose their attraction after having seen a dozen of them)
>
>        Ingo
>


Yes. I'm using the default formatting output in trace.c so perhaps
there is some iter flag I should dynamically remove
from the boot tracer to avoid that or perhaps I may format a custom
output for sched entries for the boot tracer.
I will see that....

By the way Arjan, does the actual state of the boot tracer match your needs?
You can find an example of its trace here:
http://git.kernel.org/?p=linux/kernel/git/x86/linux-2.6-tip.git;a=commit;h=74239072830ef3f1398edeb1bc1076fc330fd4a2
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