Commit 1a5bae25 authored by Anshuman Khandual's avatar Anshuman Khandual Committed by Linus Torvalds
Browse files

mm/vmstat: add events for THP migration without split 

Add following new vmstat events which will help in validating THP
migration without split.  Statistics reported through these new VM events
will help in performance debugging.

1. THP_MIGRATION_SUCCESS
2. THP_MIGRATION_FAILURE
3. THP_MIGRATION_SPLIT

In addition, these new events also update normal page migration statistics
appropriately via PGMIGRATE_SUCCESS and PGMIGRATE_FAILURE.  While here,
this updates current trace event 'mm_migrate_pages' to accommodate now
available THP statistics.

[akpm@linux-foundation.org: s/hpage_nr_pages/thp_nr_pages/]
[ziy@nvidia.com: v2]
  Link: http://lkml.kernel.org/r/C5E3C65C-8253-4638-9D3C-71A61858BB8B@nvidia.com
[anshuman.khandual@arm.com: s/thp_nr_pages/hpage_nr_pages/]
  Link: http://lkml.kernel.org/r/1594287583-16568-1-git-send-email-anshuman.khandual@arm.com



Signed-off-by: default avatarAnshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: default avatarZi Yan <ziy@nvidia.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: default avatarDaniel Jordan <daniel.m.jordan@oracle.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Zi Yan <ziy@nvidia.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Link: http://lkml.kernel.org/r/1594080415-27924-1-git-send-email-anshuman.khandual@arm.com


Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 4958e4d8

Documentation/vm/page_migration.rst

+27 −0
Original line number Diff line number Diff line
@@ -253,5 +253,32 @@ which are function pointers of struct address_space_operations. 
     PG_isolated is alias with PG_reclaim flag so driver shouldn't use the flag

     for own purpose.



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.



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

   _SUCCESS, above: this will be increased by the number of subpages, if it was

   a THP.



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



4. THP_MIGRATION_FAIL: A THP could not be migrated nor it could be split.



5. THP_MIGRATION_SPLIT: A THP was migrated, but not as such: first, the THP had

   to be split. After splitting, a migration retry was used for it's sub-pages.



THP_MIGRATION_* events also update the appropriate PGMIGRATE_SUCCESS or

PGMIGRATE_FAIL events. For example, a THP migration failure will cause both

THP_MIGRATION_FAIL and PGMIGRATE_FAIL to increase.



Christoph Lameter, May 8, 2006.

Minchan Kim, Mar 28, 2016.

include/linux/vm_event_item.h

+3 −0
Original line number Diff line number Diff line
@@ -56,6 +56,9 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT, 
#endif

#ifdef CONFIG_MIGRATION

		PGMIGRATE_SUCCESS, PGMIGRATE_FAIL,

		THP_MIGRATION_SUCCESS,

		THP_MIGRATION_FAIL,

		THP_MIGRATION_SPLIT,

#endif

#ifdef CONFIG_COMPACTION

		COMPACTMIGRATE_SCANNED, COMPACTFREE_SCANNED,

include/trace/events/migrate.h

+14 −3
Original line number Diff line number Diff line
@@ -46,13 +46,18 @@ MIGRATE_REASON 
TRACE_EVENT(mm_migrate_pages,



	TP_PROTO(unsigned long succeeded, unsigned long failed,

		 enum migrate_mode mode, int reason),

		 unsigned long thp_succeeded, unsigned long thp_failed,

		 unsigned long thp_split, enum migrate_mode mode, int reason),



	TP_ARGS(succeeded, failed, mode, reason),

	TP_ARGS(succeeded, failed, thp_succeeded, thp_failed,

		thp_split, mode, reason),



	TP_STRUCT__entry(

		__field(	unsigned long,		succeeded)

		__field(	unsigned long,		failed)

		__field(	unsigned long,		thp_succeeded)

		__field(	unsigned long,		thp_failed)

		__field(	unsigned long,		thp_split)

		__field(	enum migrate_mode,	mode)

		__field(	int,			reason)

	),
@@ -60,13 +65,19 @@ TRACE_EVENT(mm_migrate_pages, 
	TP_fast_assign(

		__entry->succeeded	= succeeded;

		__entry->failed		= failed;

		__entry->thp_succeeded	= thp_succeeded;

		__entry->thp_failed	= thp_failed;

		__entry->thp_split	= thp_split;

		__entry->mode		= mode;

		__entry->reason		= reason;

	),



	TP_printk("nr_succeeded=%lu nr_failed=%lu mode=%s reason=%s",

	TP_printk("nr_succeeded=%lu nr_failed=%lu nr_thp_succeeded=%lu nr_thp_failed=%lu nr_thp_split=%lu mode=%s reason=%s",

		__entry->succeeded,

		__entry->failed,

		__entry->thp_succeeded,

		__entry->thp_failed,

		__entry->thp_split,

		__print_symbolic(__entry->mode, MIGRATE_MODE),

		__print_symbolic(__entry->reason, MIGRATE_REASON))

);

mm/migrate.c

+44 −8
Original line number Diff line number Diff line
@@ -1418,22 +1418,35 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page, 
		enum migrate_mode mode, int reason)

{

	int retry = 1;

	int thp_retry = 1;

	int nr_failed = 0;

	int nr_succeeded = 0;

	int nr_thp_succeeded = 0;

	int nr_thp_failed = 0;

	int nr_thp_split = 0;

	int pass = 0;

	bool is_thp = false;

	struct page *page;

	struct page *page2;

	int swapwrite = current->flags & PF_SWAPWRITE;

	int rc;

	int rc, nr_subpages;



	if (!swapwrite)

		current->flags |= PF_SWAPWRITE;



	for(pass = 0; pass < 10 && retry; pass++) {

	for (pass = 0; pass < 10 && (retry || thp_retry); pass++) {

		retry = 0;

		thp_retry = 0;



		list_for_each_entry_safe(page, page2, from, lru) {

retry:

			/*

			 * THP statistics is based on the source huge page.

			 * Capture required information that might get lost

			 * during migration.

			 */

			is_thp = PageTransHuge(page);

			nr_subpages = hpage_nr_pages(page);

			cond_resched();



			if (PageHuge(page))
@@ -1464,15 +1477,30 @@ retry: 
					unlock_page(page);

					if (!rc) {

						list_safe_reset_next(page, page2, lru);

						nr_thp_split++;

						goto retry;

					}

				}

				if (is_thp) {

					nr_thp_failed++;

					nr_failed += nr_subpages;

					goto out;

				}

				nr_failed++;

				goto out;

			case -EAGAIN:

				if (is_thp) {

					thp_retry++;

					break;

				}

				retry++;

				break;

			case MIGRATEPAGE_SUCCESS:

				if (is_thp) {

					nr_thp_succeeded++;

					nr_succeeded += nr_subpages;

					break;

				}

				nr_succeeded++;

				break;

			default:
@@ -1482,19 +1510,27 @@ retry: 
				 * removed from migration page list and not

				 * retried in the next outer loop.

				 */

				if (is_thp) {

					nr_thp_failed++;

					nr_failed += nr_subpages;

					break;

				}

				nr_failed++;

				break;

			}

		}

	}

	nr_failed += retry;

	nr_failed += retry + thp_retry;

	nr_thp_failed += thp_retry;

	rc = nr_failed;

out:

	if (nr_succeeded)

	count_vm_events(PGMIGRATE_SUCCESS, nr_succeeded);

	if (nr_failed)

	count_vm_events(PGMIGRATE_FAIL, nr_failed);

	trace_mm_migrate_pages(nr_succeeded, nr_failed, mode, reason);

	count_vm_events(THP_MIGRATION_SUCCESS, nr_thp_succeeded);

	count_vm_events(THP_MIGRATION_FAIL, nr_thp_failed);

	count_vm_events(THP_MIGRATION_SPLIT, nr_thp_split);

	trace_mm_migrate_pages(nr_succeeded, nr_failed, nr_thp_succeeded,

			       nr_thp_failed, nr_thp_split, mode, reason);



	if (!swapwrite)

		current->flags &= ~PF_SWAPWRITE;

mm/vmstat.c

+3 −0
Original line number Diff line number Diff line
@@ -1277,6 +1277,9 @@ const char * const vmstat_text[] = { 
#ifdef CONFIG_MIGRATION

	"pgmigrate_success",

	"pgmigrate_fail",

	"thp_migration_success",

	"thp_migration_fail",

	"thp_migration_split",

#endif

#ifdef CONFIG_COMPACTION

	"compact_migrate_scanned",

CRA Git | Maintained and supported by SUSTech CRA and CCSE