linux-kernel - Re: [PATCH v5 11/16] perf report: properly handle branch count in match

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Message-ID: <20171013133903.GN3503@kernel.org>
Date:   Fri, 13 Oct 2017 10:39:03 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Milian Wolff <milian.wolff@...b.com>
Cc:     jolsa@...nel.org, Jin Yao <yao.jin@...ux.intel.com>,
        Linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
        Arnaldo Carvalho de Melo <acme@...hat.com>,
        David Ahern <dsahern@...il.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: Re: [PATCH v5 11/16] perf report: properly handle branch count in
 match_chain

Em Mon, Oct 09, 2017 at 10:33:05PM +0200, Milian Wolff escreveu:
> Some of the code paths I introduced before returned too early
> without running the code to handle a node's branch count.
> By refactoring match_chain to only have one exit point, this
> can be remedied.

Fixing up this one now.
 
> Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
> Cc: David Ahern <dsahern@...il.com>
> Cc: Namhyung Kim <namhyung@...nel.org>
> Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
> Cc: Yao Jin <yao.jin@...ux.intel.com>
> Signed-off-by: Milian Wolff <milian.wolff@...b.com>
> ---
>  tools/perf/util/callchain.c | 117 +++++++++++++++++++++++---------------------
>  1 file changed, 60 insertions(+), 57 deletions(-)
> 
> diff --git a/tools/perf/util/callchain.c b/tools/perf/util/callchain.c
> index 3f1431bf71bd..782de047c902 100644
> --- a/tools/perf/util/callchain.c
> +++ b/tools/perf/util/callchain.c
> @@ -666,78 +666,81 @@ static enum match_result match_chain_strings(const char *left,
>  	return ret;
>  }
>  
> +static enum match_result match_address(u64 left, u64 right)
> +{
> +	if (left == right)
> +		return MATCH_EQ;
> +	else if (left < right)
> +		return MATCH_LT;
> +	else
> +		return MATCH_GT;
> +}
> +
>  static enum match_result match_chain(struct callchain_cursor_node *node,
>  				     struct callchain_list *cnode)
>  {
> -	struct symbol *sym = node->sym;
> -	enum match_result match;
> -	u64 left, right;
> +	enum match_result match = MATCH_ERROR;
>  
> -	if (callchain_param.key == CCKEY_SRCLINE) {
> +	switch (callchain_param.key) {
> +	case CCKEY_SRCLINE:
>  		match = match_chain_strings(cnode->srcline, node->srcline);
> -
> -		/* if no srcline is available, fallback to symbol name */
> -		if (match == MATCH_ERROR && cnode->ms.sym && node->sym)
> -			match = match_chain_strings(cnode->ms.sym->name,
> -						    node->sym->name);
> -
>  		if (match != MATCH_ERROR)
> -			return match;
> -
> -		/* otherwise fall-back to IP-based comparison below */
> -	}
> -
> -	if (cnode->ms.sym && sym && callchain_param.key == CCKEY_FUNCTION) {
> -		/* compare inlined frames based on their symbol name because
> -		 * different inlined frames will have the same symbol start
> -		 */
> -		if (cnode->ms.sym->inlined || node->sym->inlined)
> -			return match_chain_strings(cnode->ms.sym->name,
> -						   node->sym->name);
> -
> -		left = cnode->ms.sym->start;
> -		right = sym->start;
> -	} else {
> -		left = cnode->ip;
> -		right = node->ip;
> +			break;
> +		__fallthrough;
> +	case CCKEY_FUNCTION:
> +		if (node->sym && cnode->ms.sym) {
> +			/* compare inlined frames based on their symbol name
> +			 * because different inlined frames will have the same
> +			 * symbol start. otherwise do a faster comparison based
> +			 * on the symbol start address
> +			 */
> +			if (cnode->ms.sym->inlined || node->sym->inlined)
> +				match = match_chain_strings(cnode->ms.sym->name,
> +							    node->sym->name);
> +			else
> +				match = match_address(cnode->ms.sym->start,
> +						      node->sym->start);
> +			if (match != MATCH_ERROR)
> +				break;
> +		}
> +		__fallthrough;
> +	case CCKEY_ADDRESS:
> +	default:
> +		match = match_address(cnode->ip, node->ip);
> +		break;
>  	}
>  
> -	if (left == right) {
> -		if (node->branch) {
> -			cnode->branch_count++;
> +	if (match == MATCH_EQ && node->branch) {
> +		cnode->branch_count++;
>  
> -			if (node->branch_from) {
> -				/*
> -				 * It's "to" of a branch
> -				 */
> -				cnode->brtype_stat.branch_to = true;
> +		if (node->branch_from) {
> +			/*
> +			 * It's "to" of a branch
> +			 */
> +			cnode->brtype_stat.branch_to = true;
>  
> -				if (node->branch_flags.predicted)
> -					cnode->predicted_count++;
> +			if (node->branch_flags.predicted)
> +				cnode->predicted_count++;
>  
> -				if (node->branch_flags.abort)
> -					cnode->abort_count++;
> +			if (node->branch_flags.abort)
> +				cnode->abort_count++;
>  
> -				branch_type_count(&cnode->brtype_stat,
> -						  &node->branch_flags,
> -						  node->branch_from,
> -						  node->ip);
> -			} else {
> -				/*
> -				 * It's "from" of a branch
> -				 */
> -				cnode->brtype_stat.branch_to = false;
> -				cnode->cycles_count +=
> -					node->branch_flags.cycles;
> -				cnode->iter_count += node->nr_loop_iter;
> -				cnode->iter_cycles += node->iter_cycles;
> -			}
> +			branch_type_count(&cnode->brtype_stat,
> +					  &node->branch_flags,
> +					  node->branch_from,
> +					  node->ip);
> +		} else {
> +			/*
> +			 * It's "from" of a branch
> +			 */
> +			cnode->brtype_stat.branch_to = false;
> +			cnode->cycles_count += node->branch_flags.cycles;
> +			cnode->iter_count += node->nr_loop_iter;
> +			cnode->iter_cycles += node->iter_cycles;
>  		}
> -
> -		return MATCH_EQ;
>  	}
>  
> -	return left > right ? MATCH_GT : MATCH_LT;
> +	return match;
>  }
>  
>  /*
> -- 
> 2.14.2