Commit 5d39a7eb authored by Baolin Wang's avatar Baolin Wang Committed by Linus Torvalds
Browse files

mm: migrate: correct the hugetlb migration stats 

Correct the migration stats for hugetlb with using compound_nr() instead
of thp_nr_pages(), meanwhile change 'nr_failed_pages' to record the
number of normal pages failed to migrate, including THP and hugetlb, and
'nr_succeeded' will record the number of normal pages migrated
successfully.

[baolin.wang@linux.alibaba.com: fix docs, per Mike]
  Link: https://lkml.kernel.org/r/141bdfc6-f898-3cc3-f692-726c5f6cb74d@linux.alibaba.com

Link: https://lkml.kernel.org/r/71a4b6c22f208728fe8c78ad26375436c4ff9704.1636275127.git.baolin.wang@linux.alibaba.com


Signed-off-by: default avatarBaolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: default avatarZi Yan <ziy@nvidia.com>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent b5bade97

Documentation/vm/page_migration.rst

+6 −6
Original line number Diff line number Diff line
@@ -263,15 +263,15 @@ Monitoring Migration 
The following events (counters) can be used to monitor page migration.



1. PGMIGRATE_SUCCESS: Normal page migration success. Each count means that a

   page was migrated. If the page was a non-THP page, then this counter is

   increased by one. If the page was a THP, then this counter is increased by

   the number of THP subpages. For example, migration of a single 2MB THP that

   has 4KB-size base pages (subpages) will cause this counter to increase by

   512.

   page was migrated. If the page was a non-THP and non-hugetlb page, then

   this counter is increased by one. If the page was a THP or hugetlb, then

   this counter is increased by the number of THP or hugetlb subpages.

   For example, migration of a single 2MB THP that has 4KB-size base pages

   (subpages) will cause this counter to increase by 512.



2. PGMIGRATE_FAIL: Normal page migration failure. Same counting rules as for

   PGMIGRATE_SUCCESS, above: this will be increased by the number of subpages,

   if it was a THP.

   if it was a THP or hugetlb.



3. THP_MIGRATION_SUCCESS: A THP was migrated without being split.

mm/migrate.c

+8 −9
Original line number Diff line number Diff line
@@ -1429,9 +1429,9 @@ static inline int try_split_thp(struct page *page, struct page **page2, 
 * It is caller's responsibility to call putback_movable_pages() to return pages

 * to the LRU or free list only if ret != 0.

 *

 * Returns the number of {normal page, THP} that were not migrated, or an error code.

 * The number of THP splits will be considered as the number of non-migrated THP,

 * no matter how many subpages of the THP are migrated successfully.

 * Returns the number of {normal page, THP, hugetlb} that were not migrated, or

 * an error code. The number of THP splits will be considered as the number of

 * non-migrated THP, no matter how many subpages of the THP are migrated successfully.

 */

int migrate_pages(struct list_head *from, new_page_t get_new_page,

		free_page_t put_new_page, unsigned long private,
@@ -1474,7 +1474,7 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page, 
			 * during migration.

			 */

			is_thp = PageTransHuge(page) && !PageHuge(page);

			nr_subpages = thp_nr_pages(page);

			nr_subpages = compound_nr(page);

			cond_resched();



			if (PageHuge(page))
@@ -1523,7 +1523,7 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page, 
				/* Hugetlb migration is unsupported */

				if (!no_subpage_counting)

					nr_failed++;

				nr_failed_pages++;

				nr_failed_pages += nr_subpages;

				break;

			case -ENOMEM:

				/*
@@ -1544,7 +1544,7 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page, 


				if (!no_subpage_counting)

					nr_failed++;

				nr_failed_pages++;

				nr_failed_pages += nr_subpages;

				goto out;

			case -EAGAIN:

				if (is_thp) {
@@ -1554,12 +1554,11 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page, 
				retry++;

				break;

			case MIGRATEPAGE_SUCCESS:

				nr_succeeded += nr_subpages;

				if (is_thp) {

					nr_thp_succeeded++;

					nr_succeeded += nr_subpages;

					break;

				}

				nr_succeeded++;

				break;

			default:

				/*
@@ -1576,7 +1575,7 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page, 


				if (!no_subpage_counting)

					nr_failed++;

				nr_failed_pages++;

				nr_failed_pages += nr_subpages;

				break;

			}

		}