linux-kernel - Re: [PATCH] perf, tools: Always use non inlined file name for srcfile

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Message-ID: <20150901183657.GG29821@kernel.org>
Date:	Tue, 1 Sep 2015 15:36:57 -0300
From:	Arnaldo Carvalho de Melo <acme@...nel.org>
To:	Andi Kleen <andi@...stfloor.org>
Cc:	linux-kernel@...r.kernel.org, jolsa@...nel.org,
	Andi Kleen <ak@...ux.intel.com>
Subject: Re: [PATCH] perf, tools: Always use non inlined file name for srcfile

Em Tue, Sep 01, 2015 at 11:11:42AM -0700, Andi Kleen escreveu:
> From: Andi Kleen <ak@...ux.intel.com>
> 
> When profiling the kernel with srcfile it's common to "get
> stuck" in include. For example a lot of code uses current
> or other inlines, so they get accounted to some random
> include file. This is not very useful as a high level
> categorization.

Cool idea :-)
 
> For example just profiling the idle loop usually shows
> mostly inlines, so you never see the actual cpuidle file.
> @@ -170,6 +171,15 @@ static int addr2line(const char *dso_name, u64 addr,
>  
>  	bfd_map_over_sections(a2l->abfd, find_address_in_section, a2l);
>  
> +	if (a2l->found && unwind_inlines) {
> +		bool found;
> +
> +		do {
> +			found = bfd_find_inliner_info(a2l->abfd, &a2l->filename,
> +						      &a2l->funcname, &a2l->line);
> +		} while (found);
> +	}

Why not the so much simpler:

		while (bfd_find_inliner_info(...));

But other than that, wouldn't be better to put an upper limit on this?

Say, 1024 levels of unwinding to avoid tripping in some bfd lib bug that
could make this function always return true and make addr2line get stuck
in an infinite loop?

- Arnaldo
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