Commit d2307fd4 authored by Ian Rogers's avatar Ian Rogers Committed by Namhyung Kim
Browse files

perf maps: Add/use a sorted insert for fixup overlap and insert 



Data may have lots of overlapping mmaps. The regular insert adds at
the end and relies on a later sort. For data with overlapping mappings
the sort will happen during a subsequent maps__find or
__maps__fixup_overlap_and_insert, there's never a period where the
inserted maps buffer up and a single sort happens. To avoid back to
back sorts, maintain the sort order when fixing up and
inserting. Previously the first_ending_after search was O(log n) where
n is the size of maps, and the insert was O(1) but because of the
continuous sorting was becoming O(n*log(n)). With maintaining sort
order, the insert now becomes O(n) for a memmove.

For a perf report on a perf.data file containing overlapping mappings
the time numbers are:

Before:
real    0m5.894s
user    0m5.650s
sys     0m0.231s

After:
real    0m0.675s
user    0m0.454s
sys     0m0.196s

Signed-off-by: default avatarIan Rogers <irogers@google.com>
Reviewed-by: default avatarJames Clark <james.clark@arm.com>
Cc: Steinar H . Gunderson <sesse@google.com>
Signed-off-by: default avatarNamhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/20240521165109.708593-4-irogers@google.com
parent aeefb043

tools/perf/util/maps.c

+59 −6
Original line number Diff line number Diff line
@@ -735,6 +735,60 @@ static unsigned int first_ending_after(struct maps *maps, const struct map *map) 
	return first;

}



static int __maps__insert_sorted(struct maps *maps, unsigned int first_after_index,

				 struct map *new1, struct map *new2)

{

	struct map **maps_by_address = maps__maps_by_address(maps);

	struct map **maps_by_name = maps__maps_by_name(maps);

	unsigned int nr_maps = maps__nr_maps(maps);

	unsigned int nr_allocate = RC_CHK_ACCESS(maps)->nr_maps_allocated;

	unsigned int to_add = new2 ? 2 : 1;



	assert(maps__maps_by_address_sorted(maps));

	assert(first_after_index == nr_maps ||

	       map__end(new1) <= map__start(maps_by_address[first_after_index]));

	assert(!new2 || map__end(new1) <= map__start(new2));

	assert(first_after_index == nr_maps || !new2 ||

	       map__end(new2) <= map__start(maps_by_address[first_after_index]));



	if (nr_maps + to_add > nr_allocate) {

		nr_allocate = !nr_allocate ? 32 : nr_allocate * 2;



		maps_by_address = realloc(maps_by_address, nr_allocate * sizeof(new1));

		if (!maps_by_address)

			return -ENOMEM;



		maps__set_maps_by_address(maps, maps_by_address);

		if (maps_by_name) {

			maps_by_name = realloc(maps_by_name, nr_allocate * sizeof(new1));

			if (!maps_by_name) {

				/*

				 * If by name fails, just disable by name and it will

				 * recompute next time it is required.

				 */

				__maps__free_maps_by_name(maps);

			}

			maps__set_maps_by_name(maps, maps_by_name);

		}

		RC_CHK_ACCESS(maps)->nr_maps_allocated = nr_allocate;

	}

	memmove(&maps_by_address[first_after_index+to_add],

		&maps_by_address[first_after_index],

		(nr_maps - first_after_index) * sizeof(new1));

	maps_by_address[first_after_index] = map__get(new1);

	if (maps_by_name)

		maps_by_name[nr_maps] = map__get(new1);

	if (new2) {

		maps_by_address[first_after_index + 1] = map__get(new2);

		if (maps_by_name)

			maps_by_name[nr_maps + 1] = map__get(new2);

	}

	RC_CHK_ACCESS(maps)->nr_maps = nr_maps + to_add;

	maps__set_maps_by_name_sorted(maps, false);

	check_invariants(maps);

	return 0;

}



/*

 * Adds new to maps, if new overlaps existing entries then the existing maps are

 * adjusted or removed so that new fits without overlapping any entries.
@@ -743,6 +797,7 @@ static int __maps__fixup_overlap_and_insert(struct maps *maps, struct map *new) 
{

	int err = 0;

	FILE *fp = debug_file();

	unsigned int i;



	if (!maps__maps_by_address_sorted(maps))

		__maps__sort_by_address(maps);
@@ -751,7 +806,7 @@ static int __maps__fixup_overlap_and_insert(struct maps *maps, struct map *new) 
	 * Iterate through entries where the end of the existing entry is

	 * greater-than the new map's start.

	 */

	for (unsigned int i = first_ending_after(maps, new); i < maps__nr_maps(maps); ) {

	for (i = first_ending_after(maps, new); i < maps__nr_maps(maps); ) {

		struct map **maps_by_address = maps__maps_by_address(maps);

		struct map *pos = maps_by_address[i];

		struct map *before = NULL, *after = NULL;
@@ -824,9 +879,7 @@ static int __maps__fixup_overlap_and_insert(struct maps *maps, struct map *new) 
				 * 'pos' mapping and therefore there are no

				 * later mappings.

				 */

				err = __maps__insert(maps, new);

				if (!err)

					err = __maps__insert(maps, after);

				err = __maps__insert_sorted(maps, i, new, after);

				map__put(after);

				check_invariants(maps);

				return err;
@@ -839,7 +892,7 @@ static int __maps__fixup_overlap_and_insert(struct maps *maps, struct map *new) 
			 */

			map__put(maps_by_address[i]);

			maps_by_address[i] = map__get(new);

			err = __maps__insert(maps, after);

			err = __maps__insert_sorted(maps, i + 1, after, NULL);

			map__put(after);

			check_invariants(maps);

			return err;
@@ -869,7 +922,7 @@ static int __maps__fixup_overlap_and_insert(struct maps *maps, struct map *new) 
		}

	}

	/* Add the map. */

	err = __maps__insert(maps, new);

	err = __maps__insert_sorted(maps, i, new, NULL);

out_err:

	return err;

}