linux-kernel - Re: [PATCH 2/2] perf map: optimize maps__fixup

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Date:   Tue, 7 Aug 2018 14:55:28 +0200
From:   Jiri Olsa <jolsa@...hat.com>
To:     Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
Cc:     linux-kernel@...r.kernel.org,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>
Subject: Re: [PATCH 2/2] perf map: optimize maps__fixup_overlappings()

On Tue, Aug 07, 2018 at 12:09:05PM +0300, Konstantin Khlebnikov wrote:
> This function splits and removes overlapping areas.
> 
> Maps in tree are ordered by start address thus we could find
> first overlap and stop if next map does not overlap.
> 
> Signed-off-by: Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
> ---
>  tools/perf/util/map.c |   21 ++++++++++++++++++---
>  1 file changed, 18 insertions(+), 3 deletions(-)
> 
> diff --git a/tools/perf/util/map.c b/tools/perf/util/map.c
> index 89ac5b5dc218..9b3f4d244ad4 100644
> --- a/tools/perf/util/map.c
> +++ b/tools/perf/util/map.c
> @@ -675,20 +675,35 @@ static void __map_groups__insert(struct map_groups *mg, struct map *map)
>  static int maps__fixup_overlappings(struct maps *maps, struct map *map, FILE *fp)
>  {
>  	struct rb_root *root;
> -	struct rb_node *next;
> +	struct rb_node *next, *first;
>  	int err = 0;
>  
>  	down_write(&maps->lock);
>  
>  	root = &maps->entries;
> -	next = rb_first(root);
>  
> +	/* find first where end > map->start, same as find_vma() */
> +	next = root->rb_node;
> +	first = NULL;
> +	while (next) {
> +		struct map *pos = rb_entry(next, struct map, rb_node);
> +
> +		if (pos->end > map->start) {
> +			first = next;
> +			if (pos->start <= map->start)
> +				break;

please use in here the call to map__overlap as in the
while loop below.. we could change map__overlap to above
(yours) overlap check, seems more straight

> +			next = next->rb_left;
> +		} else
> +			next = next->rb_right;
> +	}
> +
> +	next = first;
>  	while (next) {
>  		struct map *pos = rb_entry(next, struct map, rb_node);
>  		next = rb_next(&pos->rb_node);
>  
>  		if (!map__overlap(pos, map))
> -			continue;
> +			break;

please put in ehre the comment from changelog,
that we could stop searching in here

thanks,
jirka

>  
>  		if (verbose >= 2) {
>  
>