linux-kernel - Re: [PATCH v6 1/6] perf report: properly handle branch count in match

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Message-ID: <871sm0hyf3.fsf@linux.intel.com>
Date:   Wed, 18 Oct 2017 15:41:04 -0700
From:   Andi Kleen <ak@...ux.intel.com>
To:     Milian Wolff <milian.wolff@...b.com>
Cc:     acme@...nel.org, jolsa@...nel.org, namhyung@...nel.org,
        Linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
        Arnaldo Carvalho de Melo <acme@...hat.com>,
        David Ahern <dsahern@...il.com>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Yao Jin <yao.jin@...ux.intel.com>,
        Ravi Bangoria <ravi.bangoria@...ux.vnet.ibm.com>
Subject: Re: [PATCH v6 1/6] perf report: properly handle branch count in match_chain

Milian Wolff <milian.wolff@...b.com> writes:
>  
> +static enum match_result match_address_dso(struct dso *left_dso, u64 left_ip,
> +					   struct dso *right_dso, u64 right_ip)
> +{
> +	if (left_dso == right_dso && left_ip == right_ip)
> +		return MATCH_EQ;
> +	else if (left_ip < right_ip)
> +		return MATCH_LT;
> +	else
> +		return MATCH_GT;
> +}

So why does only the first case check the dso? Does it not matter
for the others?

Either should be checked by none or by all.


> +	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);

So what happens when there are multiple symbols with the same name?

(e.g. local for a DSO or local in a file)

> +					  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;

I assume you tested the cycle accounting still works?

-Andi