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From:   Jaewon Kim <jaewon31.kim@samsung.com>
To:     rostedt@goodmis.org, tjmercier@google.com, yuzhao@google.com,
        kaleshsingh@google.com, akpm@linux-foundation.org, vbabka@suse.cz,
        hannes@cmpxchg.org, sj@kernel.org
Cc:     linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org,
        linux-mm@kvack.org, jaewon31.kim@gmail.com,
        Jaewon Kim <jaewon31.kim@samsung.com>
Subject: [PATCH v4] vmscan: add trace events for lru_gen
Date:   Tue, 26 Sep 2023 13:22:50 +0900
Message-Id: <20230926042250.6028-1-jaewon31.kim@samsung.com>
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CMS-TYPE: 101P
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References: <CGME20230926042019epcas1p11c28533f7b7db99db9f9d8a03ddd332c@epcas1p1.samsung.com>
Precedence: bulk

As the legacy lru provides, the lru_gen needs some trace events for
debugging.

This commit introduces 2 trace events.
  trace_mm_vmscan_lru_gen_scan
  trace_mm_vmscan_lru_gen_evict

Each event is similar to the following legacy events.
  trace_mm_vmscan_lru_isolate,
  trace_mm_vmscan_lru_shrink_[in]active

Here's an example
  mm_vmscan_lru_gen_scan: classzone=2 order=0 nr_requested=4096 nr_scanned=64 nr_skipped=0 nr_taken=64 lru=anon
  mm_vmscan_lru_gen_evict: nid=0 nr_reclaimed=64 nr_dirty=0 nr_writeback=0 nr_congested=0 nr_immediate=0 nr_activate_anon=0 nr_activate_file=0 nr_ref_keep=0 nr_unmap_fail=0 priority=2 flags=RECLAIM_WB_ANON|RECLAIM_WB_ASYNC
  mm_vmscan_lru_gen_scan: classzone=1 order=0 nr_requested=4096 nr_scanned=64 nr_skipped=0 nr_taken=64 lru=file
  mm_vmscan_lru_gen_evict: nid=0 nr_reclaimed=64 nr_dirty=0 nr_writeback=0 nr_congested=0 nr_immediate=0 nr_activate_anon=0 nr_activate_file=0 nr_ref_keep=0 nr_unmap_fail=0 priority=12 flags=RECLAIM_WB_FILE|RECLAIM_WB_ASYNC

Signed-off-by: Jaewon Kim <jaewon31.kim@samsung.com>
---
v4: wrap with #ifdef CONFIG_LRU_GEN
v3: change printk format
v2: use condition and make it aligned
v1: introduce trace events
---
 include/trace/events/mmflags.h |  9 ++++
 include/trace/events/vmscan.h  | 96 ++++++++++++++++++++++++++++++++++
 mm/vmscan.c                    | 20 +++++--
 3 files changed, 120 insertions(+), 5 deletions(-)

diff --git a/include/trace/events/mmflags.h b/include/trace/events/mmflags.h
index 1478b9dd05fa..6dfe85bd4e81 100644
--- a/include/trace/events/mmflags.h
+++ b/include/trace/events/mmflags.h
@@ -274,6 +274,12 @@ IF_HAVE_VM_SOFTDIRTY(VM_SOFTDIRTY,	"softdirty"	)		\
 		EM (LRU_ACTIVE_FILE, "active_file") \
 		EMe(LRU_UNEVICTABLE, "unevictable")
 
+#ifdef CONFIG_LRU_GEN
+#define LRU_GEN_NAMES		\
+		EM (LRU_GEN_ANON, "anon") \
+		EMe(LRU_GEN_FILE, "file")
+#endif
+
 /*
  * First define the enums in the above macros to be exported to userspace
  * via TRACE_DEFINE_ENUM().
@@ -288,6 +294,9 @@ COMPACTION_PRIORITY
 /* COMPACTION_FEEDBACK are defines not enums. Not needed here. */
 ZONE_TYPE
 LRU_NAMES
+#ifdef CONFIG_LRU_GEN
+LRU_GEN_NAMES
+#endif
 
 /*
  * Now redefine the EM() and EMe() macros to map the enums to the strings
diff --git a/include/trace/events/vmscan.h b/include/trace/events/vmscan.h
index d2123dd960d5..2080ef742f89 100644
--- a/include/trace/events/vmscan.h
+++ b/include/trace/events/vmscan.h
@@ -327,6 +327,102 @@ TRACE_EVENT(mm_vmscan_lru_isolate,
 		__print_symbolic(__entry->lru, LRU_NAMES))
 );
 
+#ifdef CONFIG_LRU_GEN
+TRACE_EVENT_CONDITION(mm_vmscan_lru_gen_scan,
+	TP_PROTO(int highest_zoneidx,
+		int order,
+		unsigned long nr_requested,
+		unsigned long nr_scanned,
+		unsigned long nr_skipped,
+		unsigned long nr_taken,
+		int lru),
+
+	TP_ARGS(highest_zoneidx, order, nr_requested, nr_scanned, nr_skipped, nr_taken, lru),
+
+	TP_CONDITION(nr_scanned),
+
+	TP_STRUCT__entry(
+		__field(int, highest_zoneidx)
+		__field(int, order)
+		__field(unsigned long, nr_requested)
+		__field(unsigned long, nr_scanned)
+		__field(unsigned long, nr_skipped)
+		__field(unsigned long, nr_taken)
+		__field(int, lru)
+	),
+
+	TP_fast_assign(
+		__entry->highest_zoneidx = highest_zoneidx;
+		__entry->order = order;
+		__entry->nr_requested = nr_requested;
+		__entry->nr_scanned = nr_scanned;
+		__entry->nr_skipped = nr_skipped;
+		__entry->nr_taken = nr_taken;
+		__entry->lru = lru;
+	),
+
+	/*
+	 * classzone is previous name of the highest_zoneidx.
+	 * Reason not to change it is the ABI requirement of the tracepoint.
+	 */
+	TP_printk("classzone=%d order=%d nr_requested=%lu nr_scanned=%lu nr_skipped=%lu nr_taken=%lu lru=%s",
+		__entry->highest_zoneidx,
+		__entry->order,
+		__entry->nr_requested,
+		__entry->nr_scanned,
+		__entry->nr_skipped,
+		__entry->nr_taken,
+		__print_symbolic(__entry->lru, LRU_GEN_NAMES))
+);
+
+TRACE_EVENT(mm_vmscan_lru_gen_evict,
+
+	TP_PROTO(int nid, unsigned long nr_reclaimed,
+		struct reclaim_stat *stat, int priority, int file),
+
+	TP_ARGS(nid, nr_reclaimed, stat, priority, file),
+
+	TP_STRUCT__entry(
+		__field(unsigned long, nr_reclaimed)
+		__field(unsigned long, nr_dirty)
+		__field(unsigned long, nr_writeback)
+		__field(unsigned long, nr_congested)
+		__field(unsigned long, nr_immediate)
+		__field(unsigned int, nr_activate0)
+		__field(unsigned int, nr_activate1)
+		__field(unsigned long, nr_ref_keep)
+		__field(unsigned long, nr_unmap_fail)
+		__field(int, nid)
+		__field(int, priority)
+		__field(int, reclaim_flags)
+	),
+
+	TP_fast_assign(
+		__entry->nid = nid;
+		__entry->nr_reclaimed = nr_reclaimed;
+		__entry->nr_dirty = stat->nr_dirty;
+		__entry->nr_writeback = stat->nr_writeback;
+		__entry->nr_congested = stat->nr_congested;
+		__entry->nr_immediate = stat->nr_immediate;
+		__entry->nr_activate0 = stat->nr_activate[0];
+		__entry->nr_activate1 = stat->nr_activate[1];
+		__entry->nr_ref_keep = stat->nr_ref_keep;
+		__entry->nr_unmap_fail = stat->nr_unmap_fail;
+		__entry->priority = priority;
+		__entry->reclaim_flags = trace_reclaim_flags(file);
+	),
+
+	TP_printk("nid=%d nr_reclaimed=%lu nr_dirty=%lu nr_writeback=%lu nr_congested=%lu nr_immediate=%lu nr_activate_anon=%u nr_activate_file=%u nr_ref_keep=%lu nr_unmap_fail=%lu priority=%d flags=%s",
+		__entry->nid, __entry->nr_reclaimed,
+		__entry->nr_dirty, __entry->nr_writeback,
+		__entry->nr_congested, __entry->nr_immediate,
+		__entry->nr_activate0, __entry->nr_activate1,
+		__entry->nr_ref_keep, __entry->nr_unmap_fail,
+		__entry->priority,
+		show_reclaim_flags(__entry->reclaim_flags))
+);
+#endif
+
 TRACE_EVENT(mm_vmscan_write_folio,
 
 	TP_PROTO(struct folio *folio),
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 6f13394b112e..0c8b48bcb461 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -5005,6 +5005,7 @@ static int scan_folios(struct lruvec *lruvec, struct scan_control *sc,
 	int sorted = 0;
 	int scanned = 0;
 	int isolated = 0;
+	int skipped = 0;
 	int remaining = MAX_LRU_BATCH;
 	struct lru_gen_folio *lrugen = &lruvec->lrugen;
 	struct mem_cgroup *memcg = lruvec_memcg(lruvec);
@@ -5018,7 +5019,7 @@ static int scan_folios(struct lruvec *lruvec, struct scan_control *sc,
 
 	for (i = MAX_NR_ZONES; i > 0; i--) {
 		LIST_HEAD(moved);
-		int skipped = 0;
+		int skipped_zone = 0;
 		int zone = (sc->reclaim_idx + i) % MAX_NR_ZONES;
 		struct list_head *head = &lrugen->folios[gen][type][zone];
 
@@ -5040,16 +5041,17 @@ static int scan_folios(struct lruvec *lruvec, struct scan_control *sc,
 				isolated += delta;
 			} else {
 				list_move(&folio->lru, &moved);
-				skipped += delta;
+				skipped_zone += delta;
 			}
 
-			if (!--remaining || max(isolated, skipped) >= MIN_LRU_BATCH)
+			if (!--remaining || max(isolated, skipped_zone) >= MIN_LRU_BATCH)
 				break;
 		}
 
-		if (skipped) {
+		if (skipped_zone) {
 			list_splice(&moved, head);
-			__count_zid_vm_events(PGSCAN_SKIP, zone, skipped);
+			__count_zid_vm_events(PGSCAN_SKIP, zone, skipped_zone);
+			skipped += skipped_zone;
 		}
 
 		if (!remaining || isolated >= MIN_LRU_BATCH)
@@ -5065,6 +5067,10 @@ static int scan_folios(struct lruvec *lruvec, struct scan_control *sc,
 	__count_memcg_events(memcg, PGREFILL, sorted);
 	__count_vm_events(PGSCAN_ANON + type, isolated);
 
+#ifdef CONFIG_LRU_GEN
+	trace_mm_vmscan_lru_gen_scan(sc->reclaim_idx, sc->order, MAX_LRU_BATCH,
+			scanned, skipped, isolated, type);
+#endif
 	/*
 	 * There might not be eligible folios due to reclaim_idx. Check the
 	 * remaining to prevent livelock if it's not making progress.
@@ -5194,6 +5200,10 @@ static int evict_folios(struct lruvec *lruvec, struct scan_control *sc, int swap
 retry:
 	reclaimed = shrink_folio_list(&list, pgdat, sc, &stat, false);
 	sc->nr_reclaimed += reclaimed;
+#ifdef CONFIG_LRU_GEN
+	trace_mm_vmscan_lru_gen_evict(pgdat->node_id, reclaimed, &stat,
+				      sc->priority, type);
+#endif
 
 	list_for_each_entry_safe_reverse(folio, next, &list, lru) {
 		if (!folio_evictable(folio)) {
-- 
2.17.1