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mm/vmstat: add events for THP migration without split

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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: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Daniel 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: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Anshuman Khandual 2020-08-11 18:31:51 -07:00 committed by Linus Torvalds
parent 4958e4d86e
commit 1a5bae25e3
5 changed files with 91 additions and 11 deletions
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27
Documentation/vm/page_migration.rst
View File

@ -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.

3
include/linux/vm_event_item.h
View File

@ -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,

17
include/trace/events/migrate.h
View File

@ -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))
);

52
mm/migrate.c
View File

@ -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(PGMIGRATE_SUCCESS, nr_succeeded);
count_vm_events(PGMIGRATE_FAIL, nr_failed);
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;

3
mm/vmstat.c
View File

@ -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",