linux-kernel - Re: [PATCH 08/14] perf report: Cache cumulative callchains

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Date:	Fri, 1 Nov 2013 13:29:42 +0100
From:	Jiri Olsa <jolsa@...hat.com>
To:	Namhyung Kim <namhyung@...nel.org>
Cc:	Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Paul Mackerras <paulus@...ba.org>,
	Ingo Molnar <mingo@...nel.org>,
	Namhyung Kim <namhyung.kim@....com>,
	LKML <linux-kernel@...r.kernel.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Stephane Eranian <eranian@...gle.com>,
	Rodrigo Campos <rodrigo@...g.com.ar>,
	Arun Sharma <asharma@...com>
Subject: Re: [PATCH 08/14] perf report: Cache cumulative callchains

On Thu, Oct 31, 2013 at 03:56:10PM +0900, Namhyung Kim wrote:

SNIP

>  	 * double accounting.
> @@ -501,8 +528,29 @@ iter_add_next_cumulative_entry(struct add_entry_iter *iter,
>  {
>  	struct perf_evsel *evsel = iter->evsel;
>  	struct perf_sample *sample = iter->sample;
> +	struct cumulative_cache *ccache = iter->priv;
>  	struct hist_entry *he;
>  	int err = 0;
> +	int i;
> +
> +	/*
> +	 * Check if there's duplicate entries in the callchain.
> +	 * It's possible that it has cycles or recursive calls.
> +	 */
> +	for (i = 0; i < iter->curr; i++) {
> +		if (sort__has_sym) {
> +			if (ccache[i].sym == al->sym)
> +				return 0;
> +		} else {
> +			/* Not much we can do - just compare the dso. */
> +			if (ccache[i].dso == al->map->dso)
> +				return 0;
> +		}
> +	}

hum, do we want to prevent recursion totaly?
how about intended recursion?

also should the dso be checked together with sym?
because the symbol is defined like dso::sym

jirka
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