linux-kernel - Re: [PATCHSET 0/8] perf tools: Fix scalability problem on callchain merging (v5)

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Message-ID: <20131014075608.GA20435@gmail.com>
Date:	Mon, 14 Oct 2013 09:56:08 +0200
From:	Ingo Molnar <mingo@...nel.org>
To:	Jiri Olsa <jolsa@...hat.com>
Cc:	David Ahern <dsahern@...il.com>, Andi Kleen <andi@...stfloor.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Paul Mackerras <paulus@...ba.org>,
	Namhyung Kim <namhyung.kim@....com>,
	LKML <linux-kernel@...r.kernel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Frederic Weisbecker <fweisbec@...il.com>
Subject: Re: [PATCHSET 0/8] perf tools: Fix scalability problem on callchain
 merging (v5)


* Jiri Olsa <jolsa@...hat.com> wrote:

> > -   OPT_CALLBACK_DEFAULT('g', "call-graph", &record.opts,
> > +   OPT_CALLBACK_DEFAULT_NOOPT('g', "call-graph", &record.opts,
> 
> hum, this disables the option completely, no?
> 
> The issue is a consequence of allowing '-g' to have carry
> a value (dwarf,fp). Maybe we could have some sort of new
> OPT_OPTION type, where if its value is not recognized it
> would be passed to next option.
> 
> Or the way Ingo suggested earlier:
> 
> ---
> So, why not keep -g as a shortcut to whatever default call-graph profiling
> we want to provide (note, this does not mean it always has to be 'fp'),
> and use --call-graph for more specific variants?
> 
> a .perfconfig value could even set the default for '-g', so that you don't
> have to type '--call-graph dwarf' all the time.
> ---
> 
> I'll try to come up with something later today

So, I think we should split -g/--call-graph into _two_, separate options:

	--call-graph <variant>
	-g

instead of turning the '<variant>' configurability off. Whatever is 
configurable via .perfconfig ought to also have a command line 
counterpart. This is pretty fundamental.

Ack on the .perfconfig aspect to choose a default for -g.

Thanks,

	Ingo
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