mm/damon/core: skip updating nr_accesses_bp for each aggregation interval

damon_merge_regions_of(), which is called for each aggregation interval,
updates nr_accesses_bp to nr_accesses * 10000.  However, nr_accesses_bp is
updated for each sampling interval via damon_moving_sum() using the
aggregation interval as the moving time window.  And by the definition of
the algorithm, the value becomes same to discrete-window based sum for
each time window-aligned time.  Hence, nr_accesses_bp will be same to
nr_accesses * 10000 for each aggregation interval without explicit update.
Remove the unnecessary update of nr_accesses_bp in
damon_merge_regions_of().

Link: https://lkml.kernel.org/r/20230915025251.72816-8-sj@kernel.orgSigned-off-by: SeongJae Park <sj@kernel.org>
Cc: Brendan Higgins <brendanhiggins@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/damon/core.c

@@ -1141,8 +1141,6 @@ static void damon_merge_regions_of(struct damon_target *t, unsigned int thres,
 		else
 			r->age++;
 
-		r->nr_accesses_bp = r->nr_accesses * 10000;
-
 		if (prev && prev->ar.end == r->ar.start &&
 		    abs(prev->nr_accesses - r->nr_accesses) <= thres &&
 		    damon_sz_region(prev) + damon_sz_region(r) <= sz_limit)