From nobody Sat Sep 26 01:03:39 2026 Received: from mta0.migadu.com (out-91.mta0.migadu.com [91.218.175.91]) (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 2292A362152 for ; Mon, 7 Sep 2026 04:25:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.91 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788755130; cv=none; b=oG9w8AzFtcGwgXSHI3Y490k8auK9dlSmZHxz6Cte98DhdubUQUDamTiFsiUSeOHFSOePLBcG1JXu/dKOVXL7jQwLBX71NNCcWt6cz/7dKaxOY4PqsByA0nBJxO6eooi1UV//aXomtUo02uJ8v82Ubk0EboWMZshzAHrnSZ15YGA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788755130; c=relaxed/simple; bh=fMRMz0ejBh4DpIRYS+wm2oHU4pJhDLj/9tGMxFwRUKQ=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=Pkb2JpA5Rw9Fsxn2KB9nC374b0HBxbpkIqq4ceDI1fB9nuVLfqdXXjOLZ/VQcquryIPiP9AwJPsd3OPB2jdW4rhKvi5jw/HJk/u4zQHPb+VLijWimUPaXSlExfCQxaON1tqcsC+ElGGEEiewVZFdPTQf4wZfqvj2fyytgrB67vY= 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=byVwoUCh; arc=none smtp.client-ip=91.218.175.91 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="byVwoUCh" X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=fMRMz0ejBh4DpIRYS+wm2oHU4pJhDLj/9tGMxFwRUKQ=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1788755125; v=1; x=1789359925; b=byVwoUChGuNvb/pGK332+rp7H2BfVy6PrzCxkKSH0XnVKtTMKV8WTnuA6Z5tcCHtaazO3bUR OsmmVWivmAsPO2v3F8RgB+UVcw8teFxakftumJWTE3Q4NgPOZ1TYJPc763E95D5fxFN2/e69giF Z+LSVuRGi2b5eN1zl7AiFjNg= X-Envelope-To: linux-kernel@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id acc1ac3b5cca2887; Mon, 07 Sep 2026 04:25:25 +0000 X-Mizu-Trace-ID: acc1ac3b5cca2887 X-Migadu-Flow: FLOW_OUT From: Ridong Chen To: Steven Rostedt , Masami Hiramatsu , Andrew Morton , Johannes Weiner Cc: Mathieu Desnoyers , David Hildenbrand , Michal Hocko , Qi Zheng , Shakeel Butt , Lorenzo Stoakes , Kairui Song , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-mm@kvack.org, Ridong Chen , Ridong Chen Subject: [PATCH RFC 1/2] mm/mglru: add tracepoint for folio isolation Date: Mon, 7 Sep 2026 12:24:46 +0800 Message-Id: <20260907042447.2450663-2-ridong.chen@linux.dev> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20260907042447.2450663-1-ridong.chen@linux.dev> References: <20260907042447.2450663-1-ridong.chen@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Ridong Chen MGLRU's scan_folios() and evict_folios() emit the classic-LRU tracepoints trace_mm_vmscan_lru_isolate() and trace_mm_vmscan_lru_shrink_inactive(). Those predate MGLRU and are indistinguishable from the classic-LRU path: they carry no generation, sequence, memcg or swappiness context, so a trace of an MGLRU run cannot tell which memcg a given scan/evict belongs to, nor how far reclaim has progressed through the generations. Add mm_mglru_isolate_folios, emitted once per isolate_folios() call with the memcg id, the type actually scanned, the effective swappiness, the scanned/isolated counts, and the anon/file min_seq and max_seq. The min_seq/max_seq triplet ties each isolation to the generation layout it ran against, which the classic-LRU tracepoints cannot express. This is emitted at the isolate_folios() layer, which is MGLRU-specific and has no classic-LRU counterpart, so it neither changes nor duplicates the existing scan/evict tracepoints. Assisted-by: Claude:claude-opus-4-8 Signed-off-by: Ridong Chen --- include/trace/events/vmscan.h | 47 +++++++++++++++++++++++++++++++++++ mm/vmscan.c | 9 ++++++- 2 files changed, 55 insertions(+), 1 deletion(-) diff --git a/include/trace/events/vmscan.h b/include/trace/events/vmscan.h index 8a872990b4be..a0e3cf75294b 100644 --- a/include/trace/events/vmscan.h +++ b/include/trace/events/vmscan.h @@ -392,6 +392,53 @@ TRACE_EVENT(mm_vmscan_lru_isolate, __print_symbolic(__entry->lru, LRU_NAMES)) ); =20 +TRACE_EVENT(mm_mglru_isolate_folios, + + TP_PROTO(u64 memcg_id, + int type, + int swappiness, + unsigned long nr_scanned, + unsigned long nr_isolated, + unsigned long anon_min_seq, + unsigned long file_min_seq, + unsigned long max_seq), + + TP_ARGS(memcg_id, type, swappiness, nr_scanned, nr_isolated, + anon_min_seq, file_min_seq, max_seq), + + TP_STRUCT__entry( + __field(u64, memcg_id) + __field(int, type) + __field(int, swappiness) + __field(unsigned long, nr_scanned) + __field(unsigned long, nr_isolated) + __field(unsigned long, anon_min_seq) + __field(unsigned long, file_min_seq) + __field(unsigned long, max_seq) + ), + + TP_fast_assign( + __entry->memcg_id =3D memcg_id; + __entry->type =3D type; + __entry->swappiness =3D swappiness; + __entry->nr_scanned =3D nr_scanned; + __entry->nr_isolated =3D nr_isolated; + __entry->anon_min_seq =3D anon_min_seq; + __entry->file_min_seq =3D file_min_seq; + __entry->max_seq =3D max_seq; + ), + + TP_printk("memcg_id=3D%llu type=3D%s swappiness=3D%d nr_scanned=3D%lu nr_= isolated=3D%lu anon_min_seq=3D%lu file_min_seq=3D%lu max_seq=3D%lu", + __entry->memcg_id, + __entry->type ? "file" : "anon", + __entry->swappiness, + __entry->nr_scanned, + __entry->nr_isolated, + __entry->anon_min_seq, + __entry->file_min_seq, + __entry->max_seq) +); + TRACE_EVENT(mm_vmscan_write_folio, =20 TP_PROTO(struct folio *folio), diff --git a/mm/vmscan.c b/mm/vmscan.c index 8409ea4bbf37..771fe6827939 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -4843,6 +4843,7 @@ static int isolate_folios(unsigned long nr_to_scan, s= truct lruvec *lruvec, bool type_fallback_allowed =3D !is_single_type_reclaim(swappiness); int type =3D get_type_to_scan(lruvec, swappiness); int total_scanned =3D 0, scanned, tier; + struct lru_gen_folio *lrugen =3D &lruvec->lrugen; bool tried =3D false; =20 retry: @@ -4854,7 +4855,7 @@ static int isolate_folios(unsigned long nr_to_scan, s= truct lruvec *lruvec, if (*isolated) { *isolate_type =3D type; *isolate_scanned =3D scanned; - return total_scanned; + goto done; } =20 /* @@ -4876,6 +4877,12 @@ static int isolate_folios(unsigned long nr_to_scan, = struct lruvec *lruvec, goto retry; } =20 +done: + trace_mm_mglru_isolate_folios(mem_cgroup_id(lruvec_memcg(lruvec)), + type, swappiness, total_scanned, *isolated, + lrugen->min_seq[LRU_GEN_ANON], + lrugen->min_seq[LRU_GEN_FILE], + lrugen->max_seq); return total_scanned; } =20 --=20 2.34.1 From nobody Sat Sep 26 01:03:39 2026 Received: from mta0.migadu.com (out-99.mta0.migadu.com [91.218.175.99]) (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 0BA7A2931CE for ; Mon, 7 Sep 2026 04:25:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.99 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788755137; cv=none; b=ivYJUEeDeFtmiF0gFNNVmdNPwxCPunqkNow3QSoG+/HbFKkVlhJcH4KeKUSfWxbCG1mt2EplOfTcQwqLxKOcM7sPYUTQlEZ6d8ZJrA3yqUbvWxRNz6+D/G1rQLBqfQALDVWzaM0YVpPTdYg/1Wko9zcRDaCt3tQGeLhitJ9cLS4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788755137; c=relaxed/simple; bh=mK2et90Pf4XLD3r0uXRQiTeVcL8gxLH+/TQolfNphI4=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=GFt7scywBbQaPPoqR3i5LNeCvSPYV1+nyLakctuGf/UO4ZcH8lMFqhrG1RYPB1upqHwj2ulikAC+ZUSlLzFJdm4UK3+y+DvxIPOfgTe996fHVREAnK9sVGDHXNntebjl1yzKKVdq5Ma1+2hoPvvv3CiXmZQc/cKp5B1QG4GdKnI= 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=JTYxUOTX; arc=none smtp.client-ip=91.218.175.99 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="JTYxUOTX" X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=mK2et90Pf4XLD3r0uXRQiTeVcL8gxLH+/TQolfNphI4=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1788755134; v=1; x=1789359934; b=JTYxUOTXL1GOPawvOBiUf4pkF8n5ytKR22NHEzOCgWUj42zFrqOXedAn0vV6rG+yJwu3I1Wj P9emkQj7WgF9S/c58Hx8TRX49KFPrj2r2RwdezQAw8NyVjU45iIAxVl7IMeElZBS5OjHb7Wly9m Yh8mFhAud2C9m7BYBP+BLtRE= X-Envelope-To: linux-kernel@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id f2e3209ee265622f; Mon, 07 Sep 2026 04:25:33 +0000 X-Mizu-Trace-ID: f2e3209ee265622f X-Migadu-Flow: FLOW_OUT From: Ridong Chen To: Steven Rostedt , Masami Hiramatsu , Andrew Morton , Johannes Weiner Cc: Mathieu Desnoyers , David Hildenbrand , Michal Hocko , Qi Zheng , Shakeel Butt , Lorenzo Stoakes , Kairui Song , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-mm@kvack.org, Ridong Chen , Ridong Chen Subject: [PATCH RFC 2/2] mm/mglru: add tracepoint for inc_max_seq Date: Mon, 7 Sep 2026 12:24:47 +0800 Message-Id: <20260907042447.2450663-3-ridong.chen@linux.dev> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20260907042447.2450663-1-ridong.chen@linux.dev> References: <20260907042447.2450663-1-ridong.chen@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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, 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 --- 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) ); =20 +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 =3D memcg_id; + __entry->max_seq =3D max_seq; + __entry->anon_min_seq =3D anon_min_seq; + __entry->file_min_seq =3D file_min_seq; + ), + + TP_printk("memcg_id=3D%llu max_seq=3D%lu anon_min_seq=3D%lu file_min_seq= =3D%lu", + __entry->memcg_id, + __entry->max_seq, + __entry->anon_min_seq, + __entry->file_min_seq) +); + TRACE_EVENT(mm_vmscan_write_folio, =20 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, unsig= ned 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]); unlock: lruvec_unlock_irq(lruvec); =20 --=20 2.34.1