diff mbox series

[v5,4/7] mm: Separate move/undo doing on folio list from migrate_pages_batch()

Message ID 20240111060757.13563-5-byungchul@sk.com (mailing list archive)
State New
Headers show
Series Reduce TLB flushes by 94% by improving folio migration | expand

Commit Message

Byungchul Park Jan. 11, 2024, 6:07 a.m. UTC
Functionally, no change. This is a preparation for migrc mechanism that
requires to use separate folio lists for its own handling at migration.

Refactored migrate_pages_batch() and separated move and undo parts
operating on folio list, from migrate_pages_batch().

Signed-off-by: Byungchul Park <byungchul@sk.com>
---
 mm/migrate.c | 134 +++++++++++++++++++++++++++++++--------------------
 1 file changed, 83 insertions(+), 51 deletions(-)

Comments

Matthew Wilcox Jan. 11, 2024, 3:42 p.m. UTC | #1
On Thu, Jan 11, 2024 at 03:07:54PM +0900, Byungchul Park wrote:
> +static void migrate_folios_move(struct list_head *src_folios,
> +		struct list_head *dst_folios,
> +		free_folio_t put_new_folio, unsigned long private,
> +		enum migrate_mode mode, int reason,
> +		struct list_head *ret_folios,
> +		struct migrate_pages_stats *stats,
> +		int *retry, int *thp_retry, int *nr_failed,
> +		int *nr_retry_pages)
> +{
> +	struct folio *folio, *folio2, *dst, *dst2;
> +	bool is_thp;
> +	int nr_pages;
> +	int rc;
> +
> +	dst = list_first_entry(dst_folios, struct folio, lru);
> +	dst2 = list_next_entry(dst, lru);
> +	list_for_each_entry_safe(folio, folio2, src_folios, lru) {
> +		is_thp = folio_test_large(folio) && folio_test_pmd_mappable(folio);

You don't need to call folio_test_large() first.  folio_order() includes
a call to test_large() so it can return 0.

> +		nr_pages = folio_nr_pages(folio);

... or since you're calculating this anyway,

		is_thp = nr_pages >= HPAGE_PMD_NR
perhaps
Byungchul Park Jan. 15, 2024, 2:08 a.m. UTC | #2
On Thu, Jan 11, 2024 at 03:42:55PM +0000, Matthew Wilcox wrote:
> On Thu, Jan 11, 2024 at 03:07:54PM +0900, Byungchul Park wrote:
> > +static void migrate_folios_move(struct list_head *src_folios,
> > +		struct list_head *dst_folios,
> > +		free_folio_t put_new_folio, unsigned long private,
> > +		enum migrate_mode mode, int reason,
> > +		struct list_head *ret_folios,
> > +		struct migrate_pages_stats *stats,
> > +		int *retry, int *thp_retry, int *nr_failed,
> > +		int *nr_retry_pages)
> > +{
> > +	struct folio *folio, *folio2, *dst, *dst2;
> > +	bool is_thp;
> > +	int nr_pages;
> > +	int rc;
> > +
> > +	dst = list_first_entry(dst_folios, struct folio, lru);
> > +	dst2 = list_next_entry(dst, lru);
> > +	list_for_each_entry_safe(folio, folio2, src_folios, lru) {
> > +		is_thp = folio_test_large(folio) && folio_test_pmd_mappable(folio);
> 
> You don't need to call folio_test_large() first.  folio_order() includes
> a call to test_large() so it can return 0.
> 
> > +		nr_pages = folio_nr_pages(folio);
> 
> ... or since you're calculating this anyway,
> 
> 		is_thp = nr_pages >= HPAGE_PMD_NR

Cool. Thanks.

	Byungchul

> perhaps
Byungchul Park Jan. 15, 2024, 8:48 a.m. UTC | #3
On Mon, Jan 15, 2024 at 11:08:18AM +0900, Byungchul Park wrote:
> On Thu, Jan 11, 2024 at 03:42:55PM +0000, Matthew Wilcox wrote:
> > On Thu, Jan 11, 2024 at 03:07:54PM +0900, Byungchul Park wrote:
> > > +static void migrate_folios_move(struct list_head *src_folios,
> > > +		struct list_head *dst_folios,
> > > +		free_folio_t put_new_folio, unsigned long private,
> > > +		enum migrate_mode mode, int reason,
> > > +		struct list_head *ret_folios,
> > > +		struct migrate_pages_stats *stats,
> > > +		int *retry, int *thp_retry, int *nr_failed,
> > > +		int *nr_retry_pages)
> > > +{
> > > +	struct folio *folio, *folio2, *dst, *dst2;
> > > +	bool is_thp;
> > > +	int nr_pages;
> > > +	int rc;
> > > +
> > > +	dst = list_first_entry(dst_folios, struct folio, lru);
> > > +	dst2 = list_next_entry(dst, lru);
> > > +	list_for_each_entry_safe(folio, folio2, src_folios, lru) {
> > > +		is_thp = folio_test_large(folio) && folio_test_pmd_mappable(folio);

JFYI, in the v4 patch set, I hadn't changed the original code that I
refactored. I just copied and pasted this part from the original code.

> > 
> > You don't need to call folio_test_large() first.  folio_order() includes
> > a call to test_large() so it can return 0.
> > 
> > > +		nr_pages = folio_nr_pages(folio);
> > 
> > ... or since you're calculating this anyway,
> > 
> > 		is_thp = nr_pages >= HPAGE_PMD_NR

I didn't apply what you suggested me here to the next version yet
because I was not sure if it'd make the code more readable.

Thanks anyway!

	Byungchul

> Cool. Thanks.
> 
> 	Byungchul
> 
> > perhaps
diff mbox series

Patch

diff --git a/mm/migrate.c b/mm/migrate.c
index 397f2a6e34cb..bbe1ecef4956 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1611,6 +1611,81 @@  static int migrate_hugetlbs(struct list_head *from, new_folio_t get_new_folio,
 	return nr_failed;
 }
 
+static void migrate_folios_move(struct list_head *src_folios,
+		struct list_head *dst_folios,
+		free_folio_t put_new_folio, unsigned long private,
+		enum migrate_mode mode, int reason,
+		struct list_head *ret_folios,
+		struct migrate_pages_stats *stats,
+		int *retry, int *thp_retry, int *nr_failed,
+		int *nr_retry_pages)
+{
+	struct folio *folio, *folio2, *dst, *dst2;
+	bool is_thp;
+	int nr_pages;
+	int rc;
+
+	dst = list_first_entry(dst_folios, struct folio, lru);
+	dst2 = list_next_entry(dst, lru);
+	list_for_each_entry_safe(folio, folio2, src_folios, lru) {
+		is_thp = folio_test_large(folio) && folio_test_pmd_mappable(folio);
+		nr_pages = folio_nr_pages(folio);
+
+		cond_resched();
+
+		rc = migrate_folio_move(put_new_folio, private,
+				folio, dst, mode,
+				reason, ret_folios);
+		/*
+		 * The rules are:
+		 *	Success: folio will be freed
+		 *	-EAGAIN: stay on the unmap_folios list
+		 *	Other errno: put on ret_folios list
+		 */
+		switch(rc) {
+		case -EAGAIN:
+			*retry += 1;
+			*thp_retry += is_thp;
+			*nr_retry_pages += nr_pages;
+			break;
+		case MIGRATEPAGE_SUCCESS:
+			stats->nr_succeeded += nr_pages;
+			stats->nr_thp_succeeded += is_thp;
+			break;
+		default:
+			*nr_failed += 1;
+			stats->nr_thp_failed += is_thp;
+			stats->nr_failed_pages += nr_pages;
+			break;
+		}
+		dst = dst2;
+		dst2 = list_next_entry(dst, lru);
+	}
+}
+
+static void migrate_folios_undo(struct list_head *src_folios,
+		struct list_head *dst_folios,
+		free_folio_t put_new_folio, unsigned long private,
+		struct list_head *ret_folios)
+{
+	struct folio *folio, *folio2, *dst, *dst2;
+
+	dst = list_first_entry(dst_folios, struct folio, lru);
+	dst2 = list_next_entry(dst, lru);
+	list_for_each_entry_safe(folio, folio2, src_folios, lru) {
+		int old_page_state = 0;
+		struct anon_vma *anon_vma = NULL;
+
+		__migrate_folio_extract(dst, &old_page_state, &anon_vma);
+		migrate_folio_undo_src(folio, old_page_state & PAGE_WAS_MAPPED,
+				anon_vma, true, ret_folios);
+		list_del(&dst->lru);
+		migrate_folio_undo_dst(dst, true, put_new_folio, private);
+		dst = dst2;
+		dst2 = list_next_entry(dst, lru);
+	}
+}
+
 /*
  * migrate_pages_batch() first unmaps folios in the from list as many as
  * possible, then move the unmapped folios.
@@ -1633,7 +1708,7 @@  static int migrate_pages_batch(struct list_head *from,
 	int pass = 0;
 	bool is_thp = false;
 	bool is_large = false;
-	struct folio *folio, *folio2, *dst = NULL, *dst2;
+	struct folio *folio, *folio2, *dst = NULL;
 	int rc, rc_saved = 0, nr_pages;
 	LIST_HEAD(unmap_folios);
 	LIST_HEAD(dst_folios);
@@ -1769,42 +1844,11 @@  static int migrate_pages_batch(struct list_head *from,
 		thp_retry = 0;
 		nr_retry_pages = 0;
 
-		dst = list_first_entry(&dst_folios, struct folio, lru);
-		dst2 = list_next_entry(dst, lru);
-		list_for_each_entry_safe(folio, folio2, &unmap_folios, lru) {
-			is_thp = folio_test_large(folio) && folio_test_pmd_mappable(folio);
-			nr_pages = folio_nr_pages(folio);
-
-			cond_resched();
-
-			rc = migrate_folio_move(put_new_folio, private,
-						folio, dst, mode,
-						reason, ret_folios);
-			/*
-			 * The rules are:
-			 *	Success: folio will be freed
-			 *	-EAGAIN: stay on the unmap_folios list
-			 *	Other errno: put on ret_folios list
-			 */
-			switch(rc) {
-			case -EAGAIN:
-				retry++;
-				thp_retry += is_thp;
-				nr_retry_pages += nr_pages;
-				break;
-			case MIGRATEPAGE_SUCCESS:
-				stats->nr_succeeded += nr_pages;
-				stats->nr_thp_succeeded += is_thp;
-				break;
-			default:
-				nr_failed++;
-				stats->nr_thp_failed += is_thp;
-				stats->nr_failed_pages += nr_pages;
-				break;
-			}
-			dst = dst2;
-			dst2 = list_next_entry(dst, lru);
-		}
+		/* Move the unmapped folios */
+		migrate_folios_move(&unmap_folios, &dst_folios,
+				put_new_folio, private, mode, reason,
+				ret_folios, stats, &retry, &thp_retry,
+				&nr_failed, &nr_retry_pages);
 	}
 	nr_failed += retry;
 	stats->nr_thp_failed += thp_retry;
@@ -1813,20 +1857,8 @@  static int migrate_pages_batch(struct list_head *from,
 	rc = rc_saved ? : nr_failed;
 out:
 	/* Cleanup remaining folios */
-	dst = list_first_entry(&dst_folios, struct folio, lru);
-	dst2 = list_next_entry(dst, lru);
-	list_for_each_entry_safe(folio, folio2, &unmap_folios, lru) {
-		int old_page_state = 0;
-		struct anon_vma *anon_vma = NULL;
-
-		__migrate_folio_extract(dst, &old_page_state, &anon_vma);
-		migrate_folio_undo_src(folio, old_page_state & PAGE_WAS_MAPPED,
-				       anon_vma, true, ret_folios);
-		list_del(&dst->lru);
-		migrate_folio_undo_dst(dst, true, put_new_folio, private);
-		dst = dst2;
-		dst2 = list_next_entry(dst, lru);
-	}
+	migrate_folios_undo(&unmap_folios, &dst_folios,
+			put_new_folio, private, ret_folios);
 
 	return rc;
 }