linux-kernel - Re: [PATCH/RFC 02/16] perf top: Fix and cleanup perf_top__record_precise

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Date:	Thu, 10 Dec 2015 16:04:17 -0300
From:	Arnaldo Carvalho de Melo <acme@...nel.org>
To:	Namhyung Kim <namhyung@...nel.org>
Cc:	Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Jiri Olsa <jolsa@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>,
	David Ahern <dsahern@...il.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Andi Kleen <andi@...stfloor.org>,
	Stephane Eranian <eranian@...gle.com>,
	Adrian Hunter <adrian.hunter@...el.com>
Subject: Re: [PATCH/RFC 02/16] perf top: Fix and cleanup
 perf_top__record_precise_ip()

Em Thu, Dec 10, 2015 at 04:53:21PM +0900, Namhyung Kim escreveu:
> At first, it has duplicate ui__has_annotation() and 'sort__has_sym'
> and 'use_browser' check.  In fact, the ui__has_annotation() should be
> removed as it needs to annotate on --stdio as well.  And the
> top->sym_filter_entry is used only for stdio mode, so make it clear on
> the condition too.

So this is doing more than one thing and changes decisions about
non-trivial operations, can you please break it down into smaller
patches?
 
> Also the check will be simplifed if it sets sym before the check.  And
> omit check for 'he' since its caller (hist_iter__top_callback) only
> gets called when iter->he is not NULL.
> 
> Secondly, it converts the 'ip' argument using map__unmap_ip() before
> the call and then reverts it using map__map_ip().  This seems
> meaningless and strange since only one of them checks the 'map'.

For isntance: the following change has value and should be on a separate
patch.
 
> Finally, access the he->hists->lock only if there's an error.
> 
> Signed-off-by: Namhyung Kim <namhyung@...nel.org>
> ---
>  tools/perf/builtin-top.c | 52 ++++++++++++++++++++----------------------------
>  1 file changed, 22 insertions(+), 30 deletions(-)
> 
> diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
> index 7e2e72e6d9d1..7cd9bb69f5a6 100644
> --- a/tools/perf/builtin-top.c
> +++ b/tools/perf/builtin-top.c
> @@ -175,42 +175,40 @@ static void perf_top__record_precise_ip(struct perf_top *top,
>  					int counter, u64 ip)
>  {
>  	struct annotation *notes;
> -	struct symbol *sym;
> +	struct symbol *sym = he->ms.sym;
>  	int err = 0;
>  
> -	if (he == NULL || he->ms.sym == NULL ||
> -	    ((top->sym_filter_entry == NULL ||
> -	      top->sym_filter_entry->ms.sym != he->ms.sym) && use_browser != 1))
> +	if (sym == NULL || (use_browser == 0 &&
> +			    (top->sym_filter_entry == NULL ||
> +			     top->sym_filter_entry->ms.sym != sym)))
>  		return;
>  
> -	sym = he->ms.sym;
>  	notes = symbol__annotation(sym);
>  
>  	if (pthread_mutex_trylock(&notes->lock))
>  		return;
>  
> -	ip = he->ms.map->map_ip(he->ms.map, ip);
> -
> -	if (ui__has_annotation())
> -		err = hist_entry__inc_addr_samples(he, counter, ip);
> +	err = hist_entry__inc_addr_samples(he, counter, ip);
>  
>  	pthread_mutex_unlock(&notes->lock);
>  
> -	/*
> -	 * This function is now called with he->hists->lock held.
> -	 * Release it before going to sleep.
> -	 */
> -	pthread_mutex_unlock(&he->hists->lock);
> +	if (unlikely(err)) {
> +		/*
> +		 * This function is now called with hists->lock held.
> +		 * Release it before going to sleep.
> +		 */
> +		pthread_mutex_unlock(&he->hists->lock);
> +
> +		if (err == -ERANGE && !he->ms.map->erange_warned)
> +			ui__warn_map_erange(he->ms.map, sym, ip);
> +		else if (err == -ENOMEM) {
> +			pr_err("Not enough memory for annotating '%s' symbol!\n",
> +			       sym->name);
> +			sleep(1);
> +		}
>  
> -	if (err == -ERANGE && !he->ms.map->erange_warned)
> -		ui__warn_map_erange(he->ms.map, sym, ip);
> -	else if (err == -ENOMEM) {
> -		pr_err("Not enough memory for annotating '%s' symbol!\n",
> -		       sym->name);
> -		sleep(1);
> +		pthread_mutex_lock(&he->hists->lock);
>  	}
> -
> -	pthread_mutex_lock(&he->hists->lock);
>  }
>  
>  static void perf_top__show_details(struct perf_top *top)
> @@ -687,14 +685,8 @@ static int hist_iter__top_callback(struct hist_entry_iter *iter,
>  	struct hist_entry *he = iter->he;
>  	struct perf_evsel *evsel = iter->evsel;
>  
> -	if (sort__has_sym && single) {
> -		u64 ip = al->addr;
> -
> -		if (al->map)
> -			ip = al->map->unmap_ip(al->map, ip);
> -
> -		perf_top__record_precise_ip(top, he, evsel->idx, ip);
> -	}
> +	if (sort__has_sym && single)
> +		perf_top__record_precise_ip(top, he, evsel->idx, al->addr);
>  
>  	hist__account_cycles(iter->sample->branch_stack, al, iter->sample,
>  		     !(top->record_opts.branch_stack & PERF_SAMPLE_BRANCH_ANY));
> -- 
> 2.6.2
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