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Tue, 03 Nov 2026 02:57:59 +0000 X-Mizu-Trace-ID: 595423ef5b9c1195 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 , David Hildenbrand , Lorenzo Stoakes , Kairui Song , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Baoquan He , Baolin Wang , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-mm@kvack.org, cgroups@vger.kernel.org, bpf@vger.kernel.org (open list:BPF [MISC]:Keyword:(?:\b|_)bpf(?:\b|_)), Ridong Chen , Ridong Chen Subject: [PATCH v6 7/7] mm/mglru: add tracepoint for inc_max_seq() Date: Tue, 3 Nov 2026 10:56:10 +0800 Message-Id: <20261103025610.3738894-8-ridong.chen@linux.dev> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20261103025610.3738894-1-ridong.chen@linux.dev> References: <20261103025610.3738894-1-ridong.chen@linux.dev> X-Archived-By: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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-Rspamd-Server: rspam09 X-Stat-Signature: wpg8ms6mauueiw64bwt3ss5dpz6bxdnn X-Rspamd-Queue-Id: DF9921A0006 X-Rspam-User: X-HE-Tag: 1793674681-628113 X-HE-Meta: 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 tNH5dIA4 rgPgohw81EyoWXwIgiq4yQXAvQ0Hdy/7fxfkNdd8j1r6RlUIxFX/b4FRd4bmgKU/QK+H3HIcdplNwThy7hgg0EpiH0SRXNnjGoKyFFOyd2CjmCgodhbBPF7/HVpL7IUfFrQXTrnPzTwW6NyUyyPMeDfYBqMbRia0cdoOjkJtv1RgjK5VGZJ/elHR3i9VgCMd++Gz7IiTL2wfAWnJwosacEvyBHBGsbkJM2YryrqTa8bbC57BM2ewp1VDS1q56dPN04XoIK5nDtn9xESxAcP2D+g1h9ofZThcNe3AbP2CfwbbpsL6hs0HomqCcJa1mdflGuArZ+U/EAIeaM4YB6hQEeCYxGw== 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, as computed by lruvec_gen_size(). The nr_anon/nr_file arrays are ordered by seq rather than by generation slot: entry i holds the generation max_seq - MAX_NR_GENS + 1 + i, i.e. they go from the oldest generation to the newest, the same order as the debugfs lru_gen file, so the output can be read directly without mapping slots back to seqs. Entries for seqs below the corresponding min_seq are not in use and normally read as 0. The arrays 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 | 46 ++++++++++++++++++++++++++++++++++++++++++++++ mm/vmscan.c | 2 ++ 2 files changed, 48 insertions(+) diff --git a/mm/trace_vmscan.h b/mm/trace_vmscan.h index 8148b8224422..40d6d90f1d7a 100644 --- a/mm/trace_vmscan.h +++ b/mm/trace_vmscan.h @@ -456,6 +456,52 @@ 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; + unsigned long max_seq = lrugen->max_seq; + int i; + + __entry->memcg_id = mem_cgroup_id(lruvec_memcg(lruvec)); + __entry->max_seq = max_seq; + __entry->anon_min_seq = lrugen->min_seq[LRU_GEN_ANON]; + __entry->file_min_seq = lrugen->min_seq[LRU_GEN_FILE]; + /* from the oldest generation to the newest, as debugfs lru_gen does */ + for (i = 0; i < MAX_NR_GENS; i++) { + unsigned long seq = max_seq - MAX_NR_GENS + 1 + i; + + __entry->nr_anon[i] = + lruvec_gen_size(lrugen, LRU_GEN_ANON, seq); + __entry->nr_file[i] = + lruvec_gen_size(lrugen, LRU_GEN_FILE, seq); + } + __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 1581b73aec56..841fefa68d1f 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -4115,6 +4115,8 @@ 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); -- 2.34.1