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Sat, 31 Oct 2026 09:02:00 +0000 X-Mizu-Trace-ID: bda5cc6f278b6035 X-Migadu-Flow: FLOW_OUT From: Ridong Chen To: Steven Rostedt , Masami Hiramatsu , Andrew Morton , Johannes Weiner , Michal Hocko , Roman Gushchin , Shakeel Butt , Dave Chinner Cc: Mathieu Desnoyers , Muchun Song , Qi Zheng , Kairui Song , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Baoquan He , Baolin Wang , David Hildenbrand , Lorenzo Stoakes , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-mm@kvack.org, cgroups@vger.kernel.org (open list:CONTROL GROUP - MEMORY RESOURCE CONTROLLER (MEMCG)), bpf@vger.kernel.org (open list:BPF [MISC]:Keyword:(?:\b|_)bpf(?:\b|_)), Ridong Chen , Ridong Chen Subject: [PATCH v5 6/6] mm/mglru: add tracepoint for inc_max_seq() Date: Sat, 31 Oct 2026 17:00:41 +0800 Message-ID: <20261031090041.58574-7-ridong.chen@linux.dev> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20261031090041.58574-1-ridong.chen@linux.dev> References: <20261031090041.58574-1-ridong.chen@linux.dev> X-Archived-By: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 288CC8000D X-Stat-Signature: sdin8nzwiedjk8jqqpmaug41c34uymfj X-Rspamd-Server: rspam04 X-Spam-Status: No, score=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=4.0.1 X-Rspam-User: X-HE-Tag: 1793437321-861084 X-HE-Meta: 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 8lQh+N/V yC5q0x/mV7TSETBableVhx9DtgMoGyIFEBsB5arBxDznP+FnmgKmtbyIgzVplb3zAO3i+6LJBGzEg1M9eF+BCBcveIvzV90FRHdlpZaJQhn1VPEdSFgJrQ4JolQbOAshArp/eA6CiVH+SeN3kIcGoWxyJmhhqhdxgCID8kh0Noh7evl7jayU8qkFazLRGCADxCsonUEGu5I3T0iZ5dvCWkQP94q1pTORrmySzTGC6Y02nLdYnXeG2CVGcPjypvjNIdjfkDv54TKbblJVdsr4q9INtb3p42jIxEEwpXqX5Vre4N3rtrsqqSJ4eYqMg4s1YevXib6Ba1rppWLaPr9F43RU8EA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 From: Ridong Chen 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 while the lruvec lock is still held, with the node id, memcg id, the new max_seq, the anon and file min_seq, and the number of pages in each generation for both types, summed over zones and clamped to >= 0 the same way the debugfs lru_gen file reports them. The nr_anon/nr_file arrays are indexed by generation slot, so the emitted max_seq/min_seq say which slot holds which seq. They are printed with __print_array(), so the output is hex and its length follows MAX_NR_GENS automatically. Only the lruvec is passed in; all of the above is collected in TP_fast_assign(), so inc_max_seq() does no extra work when the event is disabled. Paired with mm_mglru_scan_folios it makes the full aging-to-eviction window observable per memcg. Signed-off-by: Ridong Chen --- mm/trace_vmscan.h | 47 +++++++++++++++++++++++++++++++++++++++++++++++ mm/vmscan.c | 2 ++ 2 files changed, 49 insertions(+) diff --git a/mm/trace_vmscan.h b/mm/trace_vmscan.h index 8148b8224422..cddf42b5849a 100644 --- a/mm/trace_vmscan.h +++ b/mm/trace_vmscan.h @@ -456,6 +456,53 @@ TRACE_EVENT(mm_mglru_scan_folios, __entry->min_seq) ); +TRACE_EVENT(mm_mglru_inc_max_seq, + + TP_PROTO(struct lruvec *lruvec), + + TP_ARGS(lruvec), + + TP_STRUCT__entry( + __field(u64, memcg_id) + __field(unsigned long, max_seq) + __field(unsigned long, anon_min_seq) + __field(unsigned long, file_min_seq) + __array(unsigned long, nr_anon, MAX_NR_GENS) + __array(unsigned long, nr_file, MAX_NR_GENS) + __field(int, nid) + ), + + TP_fast_assign( + struct lru_gen_folio *lrugen = &lruvec->lrugen; + int gen, zone; + + __entry->memcg_id = mem_cgroup_id(lruvec_memcg(lruvec)); + __entry->max_seq = lrugen->max_seq; + __entry->anon_min_seq = lrugen->min_seq[LRU_GEN_ANON]; + __entry->file_min_seq = lrugen->min_seq[LRU_GEN_FILE]; + /* summed over zones and clamped to >= 0, as debugfs lru_gen does */ + for (gen = 0; gen < MAX_NR_GENS; gen++) { + __entry->nr_anon[gen] = 0; + __entry->nr_file[gen] = 0; + for (zone = 0; zone < MAX_NR_ZONES; zone++) { + __entry->nr_anon[gen] += + max(lrugen->nr_pages[gen][LRU_GEN_ANON][zone], 0L); + __entry->nr_file[gen] += + max(lrugen->nr_pages[gen][LRU_GEN_FILE][zone], 0L); + } + } + __entry->nid = lruvec_pgdat(lruvec)->node_id; + ), + + TP_printk("nid=%d memcg_id=%llu max_seq=%lu anon_min_seq=%lu file_min_seq=%lu nr_anon=%s nr_file=%s", + __entry->nid, + __entry->memcg_id, + __entry->max_seq, + __entry->anon_min_seq, + __entry->file_min_seq, + __print_array(__entry->nr_anon, MAX_NR_GENS, sizeof(unsigned long)), + __print_array(__entry->nr_file, MAX_NR_GENS, sizeof(unsigned long))) +); #endif /* CONFIG_LRU_GEN */ TRACE_EVENT(mm_vmscan_write_folio, diff --git a/mm/vmscan.c b/mm/vmscan.c index ff51fee872f8..24cb2b7779b1 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -4134,6 +4134,8 @@ 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(lruvec); unlock: lruvec_unlock_irq(lruvec); -- 2.43.0