mm/damon/core: iterate the regions list from current point in damon_set_regions()

We iterate the whole regions list every time to get the first/last regions
intersecting with the specific range in damon_set_regions(), in order to
add new region or resize existing regions to fit in the specific range.
Actually, it is unnecessary to iterate the new added regions and the front
regions that have been checked.  Just iterate the regions list from the
current point using list_for_each_entry_from() every time to improve
performance.

The kunit tests passed:
 [PASSED] damon_test_apply_three_regions1
 [PASSED] damon_test_apply_three_regions2
 [PASSED] damon_test_apply_three_regions3
 [PASSED] damon_test_apply_three_regions4

Link: https://lkml.kernel.org/r/1662477527-13003-1-git-send-email-kaixuxia@tencent.com
Signed-off-by: Kaixu Xia <kaixuxia@tencent.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/include/linux/damon.h b/include/linux/damon.h
index 7b1f4a4882308cde8c2bed387eaceda05eb01b48..d54acec048d6fd897e111d5cf33a19d568f8398c 100644 (file)
--- a/include/linux/damon.h
+++ b/include/linux/damon.h
@@ -463,9 +463,17 @@ static inline struct damon_region *damon_last_region(struct damon_target *t)
        return list_last_entry(&t->regions_list, struct damon_region, list);
 }
 
+static inline struct damon_region *damon_first_region(struct damon_target *t)
+{
+       return list_first_entry(&t->regions_list, struct damon_region, list);
+}
+
 #define damon_for_each_region(r, t) \
        list_for_each_entry(r, &t->regions_list, list)
 
+#define damon_for_each_region_from(r, t) \
+       list_for_each_entry_from(r, &t->regions_list, list)
+
 #define damon_for_each_region_safe(r, next, t) \
        list_for_each_entry_safe(r, next, &t->regions_list, list)
 

diff --git a/mm/damon/core.c b/mm/damon/core.c
index 9964b9d007686e53ee957489788abad12a33c5be..5e00c04ceef048cc2e93352e3077cadf66c0b287 100644 (file)
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -195,6 +195,7 @@ int damon_set_regions(struct damon_target *t, struct damon_addr_range *ranges,
                        damon_destroy_region(r, t);
        }
 
+       r = damon_first_region(t);
        /* Add new regions or resize existing regions to fit in the ranges */
        for (i = 0; i < nr_ranges; i++) {
                struct damon_region *first = NULL, *last, *newr;
@@ -202,7 +203,7 @@ int damon_set_regions(struct damon_target *t, struct damon_addr_range *ranges,
 
                range = &ranges[i];
                /* Get the first/last regions intersecting with the range */
-               damon_for_each_region(r, t) {
+               damon_for_each_region_from(r, t) {
                        if (damon_intersect(r, range)) {
                                if (!first)
                                        first = r;