linux-kernel - Re: [PATCH V4 1/3] perf tools: enable LBR call stack support

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Message-ID: <871toypelb.fsf@sejong.aot.lge.com>
Date:	Thu, 20 Nov 2014 15:32:00 +0900
From:	Namhyung Kim <namhyung@...nel.org>
To:	"Liang\, Kan" <kan.liang@...el.com>
Cc:	"acme\@kernel.org" <acme@...nel.org>,
	"jolsa\@redhat.com" <jolsa@...hat.com>,
	"a.p.zijlstra\@chello.nl" <a.p.zijlstra@...llo.nl>,
	"eranian\@google.com" <eranian@...gle.com>,
	"linux-kernel\@vger.kernel.org" <linux-kernel@...r.kernel.org>,
	"mingo\@redhat.com" <mingo@...hat.com>,
	"paulus\@samba.org" <paulus@...ba.org>,
	"ak\@linux.intel.com" <ak@...ux.intel.com>
Subject: Re: [PATCH V4 1/3] perf tools: enable LBR call stack support

On Wed, 19 Nov 2014 14:32:08 +0000, Kan Liang wrote:
>> On Tue, 18 Nov 2014 16:36:55 -0500, kan liang wrote:
>> > +			if (attr->exclude_user) {
>> > +				attr->exclude_user = 0;
>> > +
>> > +				pr_warning("LBR callstack option is only available"
>> > +					   " to get user callchain information."
>> > +					   " Force exclude_user to 0.\n");
>> > +			}
>> 
>> I'm not sure what's in a higher priority - maybe I missed earlier discussion.
>> IOW what about this?
>> 
>> 			if (attr->exclude_user) {
>> 				pr_warning("LBR callstack option is only available"
>> 					   " to get user callchain information.\n");
>
> I think either is fine. I'd like to add more info "Falling back to framepointers."
> based on your changes.
> So the user know what they will get then.
>
> What do you think?

Looks good to me.  But I still slightly prefer not to override user
settings.  But it's not a strong opinion though - I'd like to here from
others.

Thanks,
Namhyung


>
> pr_warning("LBR callstack option is only available"
> 	         " to get user callchain information."
> 	          " Falling back to framepointers.\n");
>
> pr_ warning ("Cannot use LBR callstack with branch stack"
>                 " Falling back to framepointers.\n");
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