From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out30-118.freemail.mail.aliyun.com (out30-118.freemail.mail.aliyun.com [115.124.30.118]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8B89F41BA82 for ; Thu, 3 Sep 2026 10:06:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.118 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788429986; cv=none; b=raxxlXD50li2f/UebEqZ8/Fg8OG142cZfSqX9j0IsAgmGpf/wM/WFYn0Afw9AW0xhPeOgb42m+RTwBleXHOIL9L/dQR6I2IB/jzRogbl3KdpoKn8Nl65NTx8GDiXtB2933A2DRtOuqjxErCZnMVT3COZtLOxcYjMpWNf4HDUEW0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788429986; c=relaxed/simple; bh=nIkdqPKw0YSs56WtLqYavjL+GoHx0RknfouZioIQYnQ=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=g6ZkiWaz6E/b09/sYd9X9wiNQ5Zv7R8tGNbRQitLxGiMzkrnBfPmeXdwo2tUvWViIN8QvG2MZ3Gw9EMJ93HuPCKIwxA8zjmo0Z5bxWGfJhgwlzCk2XUYX0BOrH+bdiYgD3JpdpAgsFip62SI70Dg6c7JxwxJDTjT0rluyi7/bnM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com; spf=pass smtp.mailfrom=linux.alibaba.com; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b=qWIYn/nS; arc=none smtp.client-ip=115.124.30.118 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b="qWIYn/nS" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1788429981; h=Message-ID:Date:MIME-Version:Subject:To:From:Content-Type; bh=Fpdjgc9+sv9jCsQkNtcRXnZevnJDV+QJt0b62KNfz6w=; b=qWIYn/nSw24ADrsALaLu1xdMefXQXbtLaTqnMldJ8cWzz3xMYJw5Np8ForgqKp4xsXspue+VXnSnO6hkD05VbRvA5ll/UPrURShyWO2LABuufCUQjHevPVzPxhIwz5WLHmrm0papWkx211BLlv1tRQKTHaO2T9QySUeeM3MYMuk= X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R111e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=maildocker-contentspam011083073210;MF=baolin.wang@linux.alibaba.com;NM=1;PH=DS;RN=23;SR=0;TI=SMTPD_---0XAFjTM5_1788429979; Received: from 30.74.144.116(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0XAFjTM5_1788429979 cluster:ay36) by smtp.aliyun-inc.com; Thu, 03 Sep 2026 18:06:19 +0800 Message-ID: Date: Thu, 3 Sep 2026 18:06:16 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 2/7] mm/mglru: batch update lrugen->nr_pages in inc_min_seq() 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 , Kunwu Chan References: <20260901232421.40157-1-baohua@kernel.org> <20260901232421.40157-3-baohua@kernel.org> From: Baolin Wang In-Reply-To: <20260901232421.40157-3-baohua@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 9/2/26 7:24 AM, Barry Song (Xiaomi) wrote: > Currently, folio_inc_gen() updates lrugen->nr_pages for every folio > as it advances generations. Instead, accumulate the size changes > and update lrugen->nr_pages in a batch after scanning the entire > oldest generation, or when the scan stops because remaining reaches > zero. > > Since we only move folios from the oldest generation to the second > oldest generation, the active/inactive state cannot change. We can > therefore skip __lru_update_size(). Make sense to me. > > Signed-off-by: Barry Song (Xiaomi) > Tested-by: Xueyuan Chen > Reviewed-by: Lian Wang > Reviewed-by: Kunwu Chan > --- LGTM. One nit follows. Reviewed-by: Baolin Wang > mm/vmscan.c | 23 ++++++++++++++++++----- > 1 file changed, 18 insertions(+), 5 deletions(-) > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 54bce2f608ef..27494505cecc 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -3918,6 +3918,7 @@ static bool inc_min_seq(struct lruvec *lruvec, int type, int swappiness) > struct lru_gen_folio *lrugen = &lruvec->lrugen; > int hist = lru_hist_from_seq(lrugen->min_seq[type]); > int new_gen, old_gen = lru_gen_from_seq(lrugen->min_seq[type]); > + int target_gen = (old_gen + 1) % MAX_NR_GENS; > > /* For file type, skip the check if swappiness is anon only */ > if (type && (swappiness == SWAPPINESS_ANON_ONLY)) > @@ -3927,35 +3928,47 @@ static bool inc_min_seq(struct lruvec *lruvec, int type, int swappiness) > if (!type && !swappiness) > goto done; > > + VM_WARN_ON_ONCE(get_nr_gens(lruvec, type) != MAX_NR_GENS); > + VM_WARN_ON_ONCE(lru_gen_is_active(lruvec, old_gen) != > + lru_gen_is_active(lruvec, target_gen)); > /* prevent cold/hot inversion if the type is evictable */ > for (zone = 0; zone < MAX_NR_ZONES; zone++) { > struct list_head *head = &lrugen->folios[old_gen][type][zone]; > + long delta = 0; > > while (!list_empty(head)) { > struct folio *folio = lru_to_folio(head); > + long nr_pages = folio_nr_pages(folio); > int refs = folio_lru_refs(folio); > bool workingset = folio_test_workingset(folio); > + bool gen_increased; > > VM_WARN_ON_ONCE_FOLIO(folio_test_unevictable(folio), folio); > VM_WARN_ON_ONCE_FOLIO(folio_test_active(folio), folio); > VM_WARN_ON_ONCE_FOLIO(folio_is_file_lru(folio) != type, folio); > VM_WARN_ON_ONCE_FOLIO(folio_zonenum(folio) != zone, folio); > > - new_gen = folio_inc_gen(lruvec, folio); > + new_gen = __folio_inc_gen(folio, old_gen, &gen_increased); IMO, it's better to add some comments to describe why we don't need to call __lru_update_size(), in case someone thinks this needs to be fixed in the future. :)