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Received: from 30.74.144.116(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0XAH6eEv_1788486804 cluster:ay36) by smtp.aliyun-inc.com; Fri, 04 Sep 2026 09:53:24 +0800 Message-ID: Date: Fri, 4 Sep 2026 09:53:23 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 6/7] mm/mglru: move folios from oldest gen to second-oldest gen from head to tail To: "Barry Song (Xiaomi)" , akpm@linux-foundation.org, linux-mm@kvack.org Cc: axelrasmussen@google.com, baoquan.he@linux.dev, chenridong@xiaomi.com, david@kernel.org, hannes@cmpxchg.org, kasong@tencent.com, lianux.mm@gmail.com, linux-kernel@vger.kernel.org, ljs@kernel.org, lyugaofei@xiaomi.com, mhocko@kernel.org, qi.zheng@linux.dev, shakeel.butt@linux.dev, stevensd@chromium.org, wangzicheng@honor.com, weixugc@google.com, yuanchu@google.com, zhangbo56@xiaomi.com, Xueyuan Chen References: <20260901232421.40157-1-baohua@kernel.org> <20260901232421.40157-7-baohua@kernel.org> From: Baolin Wang In-Reply-To: <20260901232421.40157-7-baohua@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam11 X-Rspam-User: X-Stat-Signature: f4d1ren4eei77hwshefc4sqquk4azszb X-Rspamd-Queue-Id: 342C420006 X-HE-Tag: 1788486808-749906 X-HE-Meta: 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 BOqmYf+T wqAIQikdL8L+xOAQzuUAMbIxx76rH7Vf4ZSalr2F0kURSUcG6Px9qJOt0k8el8eS4/tvGxSkqEYKlmwWfAb44ABU5sQPAIsvXAmZOlQnvx11DWWfGn4K7AeQacNReorItWhqSJAf3AxNNaWlZsO2UGaC14Z/37dGqE7VD1ms0xp6+6B149oJwu1+bCKu3mHaMaFJ4qaEauti1/BMYGgFr1GfOwl32eQDk3D9bJpEfwPGxy7Wgl1/z0V/7gEDO9phBPLJBFfhPsjlShJXdhUzODaAW2ThKv7o4nCYKTFf7rqldyRYe8ndTR94TD/5Zv2ugqGmR+NcyHcf5TnVxQcJp6x1LVOwx7Ux8kxf0p8nqqVOLqETeqQvL3DdEQDH4dfqNvNqHxdnbD51Q4UQtsmXgJfCqLTypQIot3kElNidjfTxzYIx5+RRqDEqlQw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 9/2/26 7:24 AM, Barry Song (Xiaomi) wrote: > For reclamation, it makes sense to reclaim folios from tail to > head, as folios near the head are relatively hot. However, when > moving folios from the oldest generation to the second-oldest > generation, using the tail-to-head order would effectively cause > a cold/hot inversion. > > Signed-off-by: Barry Song (Xiaomi) > Reviewed-by: Baoquan He > Tested-by: Xueyuan Chen > Reviewed-by: Lian Wang > --- > mm/vmscan.c | 23 +++++++++++++++++++++-- > 1 file changed, 21 insertions(+), 2 deletions(-) > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 1907a946840d..76dfa9575852 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -192,11 +192,27 @@ static inline void prefetchw_prev_lru_folio(struct folio *folio, > prefetchw(&prev->flags); > } > } > + > +static inline void prefetchw_next_lru_folio(struct folio *folio, > + struct list_head *base) > +{ > + if (folio->lru.next != base) { > + struct folio *next; > + > + next = list_entry(folio->lru.next, struct folio, lru); > + prefetchw(&next->flags); > + } > +} You did not mention in the commit message why this prefetch was added. Just curious, does it really help performance?