[RFC PATCH 3/3] mm: compaction: Fix the migration stats in trace_mm_compaction_migratepages()

From: Baolin Wang
Date: Wed Nov 03 2021 - 06:51:35 EST


Now the migrate_pages() has changed to return the number of {normal page,
THP, hugetlb} instead, thus we should not use the return value to calculate
the number of pages migrated successfully. Instead we can just use the
'nr_succeeded' which indicates the number of normal pages migrated successfully
to calculate the non-migrated pages in trace_mm_compaction_migratepages().

Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
---
include/trace/events/compaction.h | 24 ++++--------------------
mm/compaction.c | 7 ++++---
2 files changed, 8 insertions(+), 23 deletions(-)

diff --git a/include/trace/events/compaction.h b/include/trace/events/compaction.h
index 54e5bf0..7d48e70 100644
--- a/include/trace/events/compaction.h
+++ b/include/trace/events/compaction.h
@@ -68,10 +68,9 @@
TRACE_EVENT(mm_compaction_migratepages,

TP_PROTO(unsigned long nr_all,
- int migrate_rc,
- struct list_head *migratepages),
+ unsigned int nr_succeeded),

- TP_ARGS(nr_all, migrate_rc, migratepages),
+ TP_ARGS(nr_all, nr_succeeded),

TP_STRUCT__entry(
__field(unsigned long, nr_migrated)
@@ -79,23 +78,8 @@
),

TP_fast_assign(
- unsigned long nr_failed = 0;
- struct list_head *page_lru;
-
- /*
- * migrate_pages() returns either a non-negative number
- * with the number of pages that failed migration, or an
- * error code, in which case we need to count the remaining
- * pages manually
- */
- if (migrate_rc >= 0)
- nr_failed = migrate_rc;
- else
- list_for_each(page_lru, migratepages)
- nr_failed++;
-
- __entry->nr_migrated = nr_all - nr_failed;
- __entry->nr_failed = nr_failed;
+ __entry->nr_migrated = nr_succeeded;
+ __entry->nr_failed = nr_all - nr_succeeded;
),

TP_printk("nr_migrated=%lu nr_failed=%lu",
diff --git a/mm/compaction.c b/mm/compaction.c
index 6e44609..b4e94cd 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -2280,6 +2280,7 @@ bool compaction_zonelist_suitable(struct alloc_context *ac, int order,
unsigned long last_migrated_pfn;
const bool sync = cc->mode != MIGRATE_ASYNC;
bool update_cached;
+ unsigned int nr_succeeded = 0;

/*
* These counters track activities during zone compaction. Initialize
@@ -2398,10 +2399,10 @@ bool compaction_zonelist_suitable(struct alloc_context *ac, int order,

err = migrate_pages(&cc->migratepages, compaction_alloc,
compaction_free, (unsigned long)cc, cc->mode,
- MR_COMPACTION, NULL);
+ MR_COMPACTION, &nr_succeeded);

- trace_mm_compaction_migratepages(cc->nr_migratepages, err,
- &cc->migratepages);
+ trace_mm_compaction_migratepages(cc->nr_migratepages,
+ nr_succeeded);

/* All pages were either migrated or will be released */
cc->nr_migratepages = 0;
--
1.8.3.1