linux-kernel - RE: [PATCH V3 3/3] perf tools: Construct LBR call chain

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Date:	Tue, 18 Nov 2014 19:40:23 +0000
From:	"Liang, Kan" <kan.liang@...el.com>
To:	'Jiri Olsa' <jolsa@...hat.com>,
	'Namhyung Kim' <namhyung@...nel.org>
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 V3 3/3] perf tools: Construct LBR call chain



> > whole
> > > >> stack.
> > > >> > +			 */
> > > >>
> > > >> Andi is using some sanity checks:
> > > >> http://marc.info/?l=linux-kernel&m=141584447819894&w=2
> > > >> I guess this could be applied in here, once his patch gets in.
> > > >>
> > > >
> > > > Are you suggesting me to remove the comments, or rebase the
> whole
> > > > patch to Andi's patch once it's merged?
> > > >
> > > > The branch history in Andi's patch is different as the call stack,
> > > > although they are both from LBR.
> > > > Andi's branch history recording branch records for taken branches,
> > > > interrupts, and exceptions.
> > > > While the LBR call stack records for the call stack.
> > >
> > > Right.  And branch history can overlap with normal callchains so
> > > additional check in there is to remove duplication.  While LBR call
> > > stack is separated to user only so there should be no overlap.
> >
> > hum, it seemed to me like the remove_loops function could be used for
> > this one as well.. but anyway I meant that this can be introduced
> > later after Andi's change gets in
> 
> I see. I will apply Andi's remove_loops.
> 

As Namhyung said, there is no overlap for LBR call stack. The user callchain 
is not a mix. It's from either LBR or FP. so remove_loops
doesn't fit to the LBR call stack. 
Sorry for the confusion from my last reply.

Thanks,
Kan  
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