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Message-ID: <c62985530812080538p3802f329vf6e12695d734f16d@mail.gmail.com>
Date: Mon, 8 Dec 2008 14:38:31 +0100
From: "Frédéric Weisbecker" <fweisbec@...il.com>
To: "Peter Zijlstra" <a.p.zijlstra@...llo.nl>
Cc: "Ingo Molnar" <mingo@...e.hu>,
"Steven Rostedt" <rostedt@...dmis.org>,
"Linux Kernel" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] tracing/function-graph-tracer: signal interrupts entry/exit points on outpout
2008/12/8 Peter Zijlstra <a.p.zijlstra@...llo.nl>:
> On Mon, 2008-12-08 at 01:54 +0100, Frederic Weisbecker wrote:
>> Impact: provide interrupt detection on output
>>
>> Suggested by Ingo.
>> If a hardirq is raised, we want it to be signaled on output, so this patch
>> adds two arrows on the output to find entry and exit points of a hardirq.
>>
>> Unfortunately, there are many interrupt entrypoints and these can be differents
>> from one arch to another.
>>
>> The approach here is one of the easiest, but doesn't shine by its scalability:
>> we have an array of the interrupt entrypoints names that we compare with the
>> symbol of the current traced function, if it matches, we draw the arrow.
>>
>> Ie:
>>
>> 1) | unlock_buffer() {
>> 1) | wake_up_bit() {
>> 1) | bit_waitqueue() {
>> 1) 0.872 us | __phys_addr();
>> 1) 2.722 us | }
>> 1) | __wake_up_bit() {
>> 1) ==> __wake_up_bit() {
>> 1) | do_IRQ() {
>
> Would be much nicer, the current proposal is lost when grepping and adds
> a weird visual break in the output.
Ok, I will apply it like this in the V2.
Thanks!
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