linux-kernel - Re: [PATCH 2/2] perf tools: Construct LBR call chain

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Date:	Wed, 12 Nov 2014 19:31:46 +0100
From:	Jiri Olsa <jolsa@...hat.com>
To:	"Liang, Kan" <kan.liang@...el.com>
Cc:	"acme@...nel.org" <acme@...nel.org>,
	"a.p.zijlstra@...llo.nl" <a.p.zijlstra@...llo.nl>,
	"eranian@...gle.com" <eranian@...gle.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"mingo@...hat.com" <mingo@...hat.com>,
	"paulus@...ba.org" <paulus@...ba.org>,
	"ak@...ux.intel.com" <ak@...ux.intel.com>
Subject: Re: [PATCH 2/2] perf tools: Construct LBR call chain

On Wed, Nov 12, 2014 at 02:37:13PM +0000, Liang, Kan wrote:
> 
> 
> > > +
> > > +	printf("... chain: nr:%" PRIu64 "\n", total_nr);
> > > +
> > > +	for (i = 0; i < callchain_nr + 1; i++)
> > >  		printf("..... %2d: %016" PRIx64 "\n",
> > >  		       i, sample->callchain->ips[i]);
> > 
> > so if there's lbr callstack info we dont display user stack part from standard
> > callchain? I think the dump code should dump out all the info..
> > 
>  
> Right, we don't display user stack part from fp if there is lbr callstack info.
> The lbr callstack info can only be captured when the user set --call-graph
> lbr. If --call-graph is set to fp and dwarf, there will be no lbr callstack info.
> 
> If the user set lbr, I think he really want the lbr info. So I think if we display
> both lbr and fp, the fp chain might be meaningless and it will confuse them.
> If the user want to do compare, they can do perf record twice with 
> different --call-graph.

hum, IMO if the user wants the dump (report -D), she wants to see
everything she got from kernel

jirka
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