Commit 95cd2522 authored by Kaixu Xia's avatar Kaixu Xia Committed by Andrew Morton
Browse files

mm/damon/vaddr: remove comparison between mm and last_mm when checking region accesses 

The damon regions that belong to the same damon target have the same
'struct mm_struct *mm', so it's unnecessary to compare the mm and last_mm
objects among the damon regions in one damon target when checking
accesses.  But the check is necessary when the target changed in
'__damon_va_check_accesses()', so we can simplify the whole operation by
using the bool 'same_target' to indicate whether the target changed.

Link: https://lkml.kernel.org/r/1661590971-20893-3-git-send-email-kaixuxia@tencent.com


Signed-off-by: default avatarKaixu Xia <kaixuxia@tencent.com>
Reviewed-by: default avatarSeongJae Park <sj@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 09876ae7

mm/damon/vaddr.c

+6 −5
Original line number Diff line number Diff line
@@ -543,15 +543,14 @@ static bool damon_va_young(struct mm_struct *mm, unsigned long addr, 
 * r	the region to be checked

 */

static void __damon_va_check_access(struct mm_struct *mm,

				struct damon_region *r)

				struct damon_region *r, bool same_target)

{

	static struct mm_struct *last_mm;

	static unsigned long last_addr;

	static unsigned long last_page_sz = PAGE_SIZE;

	static bool last_accessed;



	/* If the region is in the last checked page, reuse the result */

	if (mm == last_mm && (ALIGN_DOWN(last_addr, last_page_sz) ==

	if (same_target && (ALIGN_DOWN(last_addr, last_page_sz) ==

				ALIGN_DOWN(r->sampling_addr, last_page_sz))) {

		if (last_accessed)

			r->nr_accesses++;
@@ -562,7 +561,6 @@ static void __damon_va_check_access(struct mm_struct *mm, 
	if (last_accessed)

		r->nr_accesses++;



	last_mm = mm;

	last_addr = r->sampling_addr;

}
@@ -572,14 +570,17 @@ static unsigned int damon_va_check_accesses(struct damon_ctx *ctx) 
	struct mm_struct *mm;

	struct damon_region *r;

	unsigned int max_nr_accesses = 0;

	bool same_target;



	damon_for_each_target(t, ctx) {

		mm = damon_get_mm(t);

		if (!mm)

			continue;

		same_target = false;

		damon_for_each_region(r, t) {

			__damon_va_check_access(mm, r);

			__damon_va_check_access(mm, r, same_target);

			max_nr_accesses = max(r->nr_accesses, max_nr_accesses);

			same_target = true;

		}

		mmput(mm);

	}