linux-kernel - Re: [PATCH V6 17/17] perf tools: choose to dump callchain from LBR and FP

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Message-ID: <20141024133600.GC1036@krava.brq.redhat.com>
Date:	Fri, 24 Oct 2014 15:36:01 +0200
From:	Jiri Olsa <jolsa@...hat.com>
To:	Kan Liang <kan.liang@...el.com>
Cc:	a.p.zijlstra@...llo.nl, eranian@...gle.com,
	linux-kernel@...r.kernel.org, mingo@...hat.com, paulus@...ba.org,
	acme@...nel.org, ak@...ux.intel.com
Subject: Re: [PATCH V6 17/17] perf tools: choose to dump callchain from LBR
 and FP

On Sun, Oct 19, 2014 at 05:55:12PM -0400, Kan Liang wrote:

SNIP

> -				return 0;
> -			}
> -			continue;
> +		mix_chain_nr = i + 2 + lbr_nr;
> +		if (mix_chain_nr > PERF_MAX_STACK_DEPTH) {
> +			pr_warning("corrupted callchain. skipping...\n");
> +			return 0;
>  		}
>  
> -		al.filtered = 0;
> -		thread__find_addr_location(thread, machine, cpumode,
> -					   MAP__FUNCTION, ip, &al);
> -		if (al.sym != NULL) {
> -			if (sort__has_parent && !*parent &&
> -			    symbol__match_regex(al.sym, &parent_regex))
> -				*parent = al.sym;
> -			else if (have_ignore_callees && root_al &&
> -			  symbol__match_regex(al.sym, &ignore_callees_regex)) {
> -				/* Treat this symbol as the root,
> -				   forgetting its callees. */
> -				*root_al = al;
> -				callchain_cursor_reset(&callchain_cursor);
> +		for (j = 0; j < mix_chain_nr; j++) {
> +			struct addr_location al;
> +
> +			if (callchain_param.order == ORDER_CALLEE) {
> +				if (j < i + 2)
> +					ip = chain->ips[j];
> +				else
> +					ip = lbr_stack->entries[j - i - 2].from;
> +			} else {
> +				if (j < lbr_nr)
> +					ip = lbr_stack->entries[lbr_nr - j - 1].from;
> +				else
> +					ip = chain->ips[i + 1 - (j - lbr_nr)];
>  			}
> +			err = __machine__resolve_callchain_sample(machine,
> +				thread, ip, &cpumode, parent, root_al, &al);
> +			/* Discard all when the callchain is corrupted */
> +			if (err > 0)
> +				return 0;
> +			else if (err)
> +				return err;

so you print FP callchains followed by LBR stack data, right?

but AFAICS from kernel changes the FP callchains and LBR callchains
data are unrelated.. 2 datasources of the same information

do we rather want to print them separately? or using an option
as Andi did in his lbr-as-callgraph patchset:
  http://marc.info/?l=linux-kernel&m=141177467802602&w=2

thanks,
jirka
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