linux-kernel - Re: [RFC/PATCH 3/3] perf tools: Defaults to 'caller' callchain order only if --children is enabled

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Date:	Fri, 23 Oct 2015 00:51:01 +0900
From:	Namhyung Kim <namhyung@...nel.org>
To:	Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:	Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Jiri Olsa <jolsa@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>,
	David Ahern <dsahern@...il.com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Borislav Petkov <bp@...e.de>,
	Brendan Gregg <brendan.d.gregg@...il.com>,
	Chandler Carruth <chandlerc@...il.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Stephane Eranian <eranian@...gle.com>,
	Wang Nan <wangnan0@...wei.com>
Subject: Re: [RFC/PATCH 3/3] perf tools: Defaults to 'caller' callchain order
 only if --children is enabled

On Thu, Oct 22, 2015 at 11:37 PM, Arnaldo Carvalho de Melo
<acme@...nel.org> wrote:
> Em Thu, Oct 22, 2015 at 11:22:40PM +0900, Namhyung Kim escreveu:
>> On Thu, Oct 22, 2015 at 11:13 PM, Arnaldo Carvalho de Melo <acme@...nel.org> wrote:
>> > Em Thu, Oct 22, 2015 at 03:28:50PM +0900, Namhyung Kim escreveu:
>> >> +++ b/tools/perf/util/util.c
>> >> @@ -19,7 +19,7 @@
>> >>  struct callchain_param       callchain_param = {
>> >>       .mode   = CHAIN_GRAPH_ABS,
>> >> -     .order  = ORDER_CALLER,
>> >> +     .order  = ORDER_CALLEE,
>
>> > So, this isn't a revert of the previous default change, i.e. previously
>> > we used CHAIN_GRAPH_REL, should we keep CHAIN_GRAPH_ABS + callee?
>
>> Yes, it's not a revert.  I intentionally didn't change the print type.
>
> Ok, its just that I don't recall seeing the part of the discussion about
> keeping the change from REL to ABS.
>
>> > Also you forgot to fix the docs to mention this new default, I did it
>> > and the resulting patch, still with GRAPH_ABS follows:
>
>> This is not simple.  As Brendan said, --children is default on, so
>> users will see 'caller' ordering that's why I didn't change the doc.
>
> Ok, but the default as it stands after applying this patch is "graph,
> calee", so the docs should be changed to reflect that, yes, its not just
> that, we need to tell, in the --children doc, that it defaults to
> "caller".
>
> Will we also flip the default to --no-children? I would advocate that,
> together with showing a info box telling the user about this change and
> how to ask for it, including instructions on how to do that via
> ~/.perfconfig.

Not sure.  It seems too late to do it. ;-)

>
>> But I should mention it'll use 'callee' ordering when --no-chlidren.
>> I'm about to send doc fix patch Ingo requested, so please leave this
>> patch as is.
>
> Ok, its just that I thought you was already asleep and was wanting to
> make progress on this 8-)

Yeah, it's late.  I'll go to bed soon.. :)

>
> Will wait for your patches and instead try to fix the annotation bug
> that leads 'perf report --tui -S some_symbol_name' to exit without
> printing anything, that Ingo reported, only happens in --tui, because
> --stdio doesn't collects annotation info...

I guess -S option works only for symbols that have self overhead..

Thanks,
Namhyung
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