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: Ian Rogers <irogers@google.com>
Reviewed-by: James Clark <james.clark@arm.com>
Cc: Steinar H . Gunderson <sesse@google.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/20240521165109.708593-4-irogers@google.com

diff --git a/tools/perf/util/maps.c b/tools/perf/util/maps.c
index f6b6df82f4cf6c67ac0060da24aecc951092c1d4..432399cbe5dd3993cc64a190223ed9e195b3bb54 100644 (file)
--- a/tools/perf/util/maps.c
+++ b/tools/perf/util/maps.c
@@ -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;
 }