[PATCH 5/6] mm: compaction: add trace event for fast freepages isolation

[Baolin Wang]

The fast_isolate_freepages() can also isolate freepages, but we can not
know the fast isolation efficiency to understand the fast isolation pressure.
So add a trace event to show some numbers to help to understand the efficiency
for fast freepages isolation.

Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
---
 include/trace/events/compaction.h | 11 +++++++++++
 mm/compaction.c                   |  6 +++++-
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/include/trace/events/compaction.h b/include/trace/events/compaction.h
index 3313eb83c117..2b2a975efd20 100644
--- a/include/trace/events/compaction.h
+++ b/include/trace/events/compaction.h
@@ -64,6 +64,17 @@ DEFINE_EVENT(mm_compaction_isolate_template, mm_compaction_isolate_freepages,
 	TP_ARGS(start_pfn, end_pfn, nr_scanned, nr_taken)
 );
 
+DEFINE_EVENT(mm_compaction_isolate_template, mm_compaction_fast_isolate_freepages,
+
+	TP_PROTO(
+		unsigned long start_pfn,
+		unsigned long end_pfn,
+		unsigned long nr_scanned,
+		unsigned long nr_taken),
+
+	TP_ARGS(start_pfn, end_pfn, nr_scanned, nr_taken)
+);
+
 #ifdef CONFIG_COMPACTION
 TRACE_EVENT(mm_compaction_migratepages,
 
diff --git a/mm/compaction.c b/mm/compaction.c
index 65d8d9223acc..eccec84dae82 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -1438,7 +1438,7 @@ static int next_search_order(struct compact_control *cc, int order)
 static void fast_isolate_freepages(struct compact_control *cc)
 {
 	unsigned int limit = max(1U, freelist_scan_limit(cc) >> 1);
-	unsigned int nr_scanned = 0;
+	unsigned int nr_scanned = 0, total_isolated = 0;
 	unsigned long low_pfn, min_pfn, highest = 0;
 	unsigned long nr_isolated = 0;
 	unsigned long distance;
@@ -1537,6 +1537,7 @@ static void fast_isolate_freepages(struct compact_control *cc)
 				set_page_private(page, order);
 				nr_isolated = 1 << order;
 				nr_scanned += nr_isolated - 1;
+				total_isolated += nr_isolated;
 				cc->nr_freepages += nr_isolated;
 				list_add_tail(&page->lru, &cc->freepages);
 				count_compact_events(COMPACTISOLATED, nr_isolated);
@@ -1557,6 +1558,9 @@ static void fast_isolate_freepages(struct compact_control *cc)
 			limit = max(1U, limit >> 1);
 	}
 
+	trace_mm_compaction_fast_isolate_freepages(min_pfn, cc->free_pfn,
+						   nr_scanned, total_isolated);
+
 	if (!page) {
 		cc->fast_search_fail++;
 		if (scan_start) {
-- 
2.27.0