From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta0.migadu.com (out-45.mta0.migadu.com [91.218.175.45]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 04AA24570F9 for ; Mon, 19 Oct 2026 04:24:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.45 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792383866; cv=none; b=Yfjr3PZfjeRo2bAJGdj3xBgUVukJzEyfbgP0J2t243GB5GUAVU/Eip2wKM7aQxVCiECo3UOnVOSQWPcKjvCLqJuXhG0jqGDNeLWhtA/R8op7So8sxljK7QgkfBvJ3nimrJblyLJjqr7Ns6WkrgWfbclFD6CD1LvAQn/umzlGuac= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792383866; c=relaxed/simple; bh=rgCPstrZqNeEdMXP/SoDZYcPpE8lXWIHRU+cnN2B2DQ=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=D21MiQYRAbEYHALPQkc7oj+DcPHdh6K7YRw65ppw+PY399ECQR81b8RwtgRXSh/0nyHCumS1dllx3/SyF6rnbP4eXtCyLkxPAfXa2dFctke7CJFlgZ84I73xvHWPo5Kq+apqmJPPS/VG7KDxauSsMZZsclwWLI9yXSUuQxZ3loc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=UtBOYQeT; arc=none smtp.client-ip=91.218.175.45 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="UtBOYQeT" X-Envelope-To: linux-trace-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=rgCPstrZqNeEdMXP/SoDZYcPpE8lXWIHRU+cnN2B2DQ=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1792383857; v=1; x=1792988657; b=UtBOYQeTvAeOkvPL5rT9MKUJj+4fbyTR8TCfgiIxaugA1ujuINo44eeFE8CPilvw/nTrVV4d NqAGKiob+r9yWe5tHwsfsWu9WQpCOQeI+ViliJuNYGUIyIJY37KkYUlpgbIgV6NX9kQVGPpvHx8 BJFiHTZmfc28ImkgRKVdSKEo= X-Envelope-To: linux-trace-kernel@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id a7533987bd4880b4; Mon, 19 Oct 2026 04:24:17 +0000 X-Mizu-Trace-ID: a7533987bd4880b4 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, Ridong Chen , Ridong Chen Subject: [PATCH v4 9/9] mm/mglru: add tracepoint for inc_max_seq() Date: Mon, 19 Oct 2026 12:23:08 +0800 Message-Id: <20261019042308.2372396-4-ridong.chen@linux.dev> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20261019034426.2354049-1-ridong.chen@linux.dev> References: <20261019034426.2354049-1-ridong.chen@linux.dev> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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. Assisted-by: LLM 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 d459678c5ee5..7b9b1aca5c88 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -4129,6 +4129,8 @@ 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