From: Ridong Chen <[email protected]>
Aging in MGLRU advances max_seq via inc_max_seq(), creating a new
youngest generation. There is currently no tracepoint on this path, so
the moment a new generation is created, and how the min_seq of each type
trails behind it, cannot be observed as it happens.
Add mm_mglru_inc_max_seq, emitted right after max_seq is bumped, with
the memcg id and the new max_seq alongside the anon and file min_seq.
Paired with the mm_mglru_isolate_folios tracepoint it makes the full
aging-to-eviction window observable per memcg.
Assisted-by: Claude:claude-opus-4-8
Signed-off-by: Ridong Chen <[email protected]>
---
include/trace/events/vmscan.h | 30 ++++++++++++++++++++++++++++++
mm/vmscan.c | 4 ++++
2 files changed, 34 insertions(+)
diff --git a/include/trace/events/vmscan.h b/include/trace/events/vmscan.h
index a0e3cf75294b..ab93c2f4b318 100644
--- a/include/trace/events/vmscan.h
+++ b/include/trace/events/vmscan.h
@@ -439,6 +439,36 @@ TRACE_EVENT(mm_mglru_isolate_folios,
__entry->max_seq)
);
+TRACE_EVENT(mm_mglru_inc_max_seq,
+
+ TP_PROTO(u64 memcg_id,
+ unsigned long max_seq,
+ unsigned long anon_min_seq,
+ unsigned long file_min_seq),
+
+ TP_ARGS(memcg_id, max_seq, anon_min_seq, file_min_seq),
+
+ TP_STRUCT__entry(
+ __field(u64, memcg_id)
+ __field(unsigned long, max_seq)
+ __field(unsigned long, anon_min_seq)
+ __field(unsigned long, file_min_seq)
+ ),
+
+ TP_fast_assign(
+ __entry->memcg_id = memcg_id;
+ __entry->max_seq = max_seq;
+ __entry->anon_min_seq = anon_min_seq;
+ __entry->file_min_seq = file_min_seq;
+ ),
+
+ TP_printk("memcg_id=%llu max_seq=%lu anon_min_seq=%lu file_min_seq=%lu",
+ __entry->memcg_id,
+ __entry->max_seq,
+ __entry->anon_min_seq,
+ __entry->file_min_seq)
+);
+
TRACE_EVENT(mm_vmscan_write_folio,
TP_PROTO(struct folio *folio),
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 771fe6827939..3c806a57d113 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -4065,6 +4065,10 @@ static bool inc_max_seq(struct lruvec *lruvec, unsigned
long seq, int swappiness
WRITE_ONCE(lrugen->timestamps[next], jiffies);
/* make sure preceding modifications appear */
smp_store_release(&lrugen->max_seq, lrugen->max_seq + 1);
+ trace_mm_mglru_inc_max_seq(mem_cgroup_id(lruvec_memcg(lruvec)),
+ lrugen->max_seq,
+ lrugen->min_seq[LRU_GEN_ANON],
+ lrugen->min_seq[LRU_GEN_FILE]);
