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Message-ID: <4939EB18.6090606@gmail.com>
Date: Sat, 06 Dec 2008 04:01:44 +0100
From: Frederic Weisbecker <fweisbec@...il.com>
To: Ingo Molnar <mingo@...e.hu>
CC: Steven Rostedt <rostedt@...dmis.org>,
Linux Kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/3] tracing/function-graph-tracer: introduce __notrace_funcgraph
to filter special functions
Frederic Weisbecker wrote:
> Impact: trace more functions
>
> When the function graph tracer is configured, three more files are not traced to prevent
> only four functions to be traced. And this impacts the normal function tracer too.
>
> arch/x86/kernel/process_64/32.c:
>
> I had crashes when I let this file traced. After some debugging, I saw that
> the "current" task point was changed inside__swtich_to(), ie: "write_pda(pcurrent, next_p);"
> inside process_64.c
> Since the tracer store the original return address of the function inside current, we had crashes.
> Only __switch_to() has to be traced.
>
> kernel/module.c and kernel/extable.c:
>
> Because of a function used internally by the function graph tracer: __kernel_text_address()
>
> To let the other functions inside these files to be traced, this patch introduces the
> __notrace_funcgraph function prefix which is __notrace if function graph tracer is
> configured and nothing if not.
>
And once again I...did not test under x86-32 :-s
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