From: Anshuman Khandual <anshuman.khandual@arm.com>
To: linux-mm@kvack.org
Cc: Anshuman Khandual <anshuman.khandual@arm.com>,
Jonathan Corbet <corbet@lwn.net>,
Steven Rostedt <rostedt@goodmis.org>,
Ingo Molnar <mingo@redhat.com>,
Daniel Jordan <daniel.m.jordan@oracle.com>,
Hugh Dickins <hughd@google.com>,
Matthew Wilcox <willy@infradead.org>, Zi Yan <ziy@nvidia.com>,
John Hubbard <jhubbard@nvidia.com>,
Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH V4] mm/vmstat: Add events for THP migration without split
Date: Thu, 9 Jul 2020 15:09:43 +0530 [thread overview]
Message-ID: <1594287583-16568-1-git-send-email-anshuman.khandual@arm.com> (raw)
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_FAIL
3. THP_MIGRATION_SPLIT
In addition, these new events also update normal page migration statistics
appropriately via PGMIGRATE_SUCCESS and PGMIGRATE_FAIL. While here, this
updates current trace event 'mm_migrate_pages' to accommodate now available
THP statistics.
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: 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>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-doc@vger.kernel.org
Cc: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Zi Yan <ziy@nvidia.com>
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
---
Applies on 5.8-rc4.
Changes in V4:
- Changed THP_MIGRATION_FAILURE as THP_MIGRATION_FAIL per John
- Dropped all conditional 'if' blocks in migrate_pages() per Andrew and John
- Updated migration events documentation per John
- Updated thp_nr_pages variable as nr_subpages for an expected merge conflict
- Moved all new THP vmstat events into CONFIG_MIGRATION
- Updated Cc list with Documentation/ and tracing related addresses
Changes in V3: (https://patchwork.kernel.org/patch/11647237/)
- Formatted new events documentation with 'fmt' tool per Matthew
- Made events universally available i.e dropped ARCH_ENABLE_THP_MIGRATION
- Added THP_MIGRATION_SPLIT
- Updated trace_mm_migrate_pages() with THP events
- Made THP events update normal page migration events as well
Changes in V2: (https://patchwork.kernel.org/patch/11586893/)
- Dropped PMD reference both from code and commit message per Matthew
- Added documentation and updated the commit message per Daniel
Changes in V1: (https://patchwork.kernel.org/patch/11564497/)
- Changed function name as thp_pmd_migration_success() per John
- Folded in a fix (https://patchwork.kernel.org/patch/11563009/) from Hugh
Changes in RFC V2: (https://patchwork.kernel.org/patch/11554861/)
- Decopupled and renamed VM events from their implementation per Zi and John
- Added THP_PMD_MIGRATION_FAILURE VM event upon allocation failure and split
Changes in RFC V1: (https://patchwork.kernel.org/patch/11542055/)
Documentation/vm/page_migration.rst | 27 +++++++++++++++
include/linux/vm_event_item.h | 3 ++
include/trace/events/migrate.h | 17 ++++++++--
mm/migrate.c | 52 ++++++++++++++++++++++++-----
mm/vmstat.c | 3 ++
5 files changed, 91 insertions(+), 11 deletions(-)
diff --git a/Documentation/vm/page_migration.rst b/Documentation/vm/page_migration.rst
index 1d6cd7db4e43..68883ac485fa 100644
--- a/Documentation/vm/page_migration.rst
+++ b/Documentation/vm/page_migration.rst
@@ -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.
diff --git a/include/linux/vm_event_item.h b/include/linux/vm_event_item.h
index 24fc7c3ae7d6..2e6ca53b9bbd 100644
--- a/include/linux/vm_event_item.h
+++ b/include/linux/vm_event_item.h
@@ -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,
diff --git a/include/trace/events/migrate.h b/include/trace/events/migrate.h
index 705b33d1e395..4d434398d64d 100644
--- a/include/trace/events/migrate.h
+++ b/include/trace/events/migrate.h
@@ -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))
);
diff --git a/mm/migrate.c b/mm/migrate.c
index f37729673558..c706e3576cfc 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1429,22 +1429,35 @@ 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))
@@ -1475,15 +1488,30 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page,
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:
@@ -1493,19 +1521,27 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page,
* 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;
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 3fb23a21f6dd..09914a4bfee4 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1234,6 +1234,9 @@ 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",
--
2.20.1
next reply other threads:[~2020-07-09 9:40 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-09 9:39 Anshuman Khandual [this message]
2020-07-09 15:34 ` [PATCH V4] mm/vmstat: Add events for THP migration without split Randy Dunlap
2020-07-09 16:34 ` Zi Yan
2020-07-09 16:39 ` Randy Dunlap
2020-07-09 17:42 ` Zi Yan
2020-07-09 20:15 ` John Hubbard
2020-07-09 21:24 ` Randy Dunlap
2020-07-10 3:41 ` Anshuman Khandual
2020-07-24 15:04 ` Daniel Jordan
2020-07-10 3:30 ` Anshuman Khandual
2020-07-10 3:33 ` Randy Dunlap
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