From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 521EEC531FA for ; Sun, 26 Jul 2026 01:30:14 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 4734D6B008C; Sat, 25 Jul 2026 21:30:09 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 424CF6B0095; Sat, 25 Jul 2026 21:30:09 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 361D76B0096; Sat, 25 Jul 2026 21:30:09 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id C9CD36B008C for ; Sat, 25 Jul 2026 21:30:05 -0400 (EDT) Received: from smtpin19.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay06.hostedemail.com (Postfix) with ESMTP id D4DE2A147A for ; Sun, 26 Jul 2026 01:30:04 +0000 (UTC) X-FDA: 85029196728.19.3D17537 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf04.hostedemail.com (Postfix) with ESMTP id 312F140009 for ; Sun, 26 Jul 2026 01:30:03 +0000 (UTC) Authentication-Results: imf04.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b="B/c/+WNY"; spf=pass (imf04.hostedemail.com: domain of baohua@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=baohua@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1785029403; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=9jhQTuuPD9KwcoX/z0WxrFRGD97WTuKY5ASJ3vGdEAY=; b=w1J0a1MdqnTYA8QgKpxe05m61dABlrTyFMkoEpl213yWDHbgx4T4b53pHl9VBcswOOxPG/ EDiJ1CnyqcZt9i+xYnv/GIDwaiRKtb8UPSnzkgA4AbHphKGuq5tlFOrz8bn9HZMpd2zDb/ RpCdaa46UosbNu6LEQCjn62wzlj+dSM= ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1785029403; b=mMcdt7ZlLM6S1JGffc7SdrTGGEXNvt+IMyiN31YzVJj8earp/NKHMUo2PJB55L1qpuIZLu iQvP5v4ica/+JvpGI1T1Ad4AI5U2uN/XKfLtWgQ+x6/W7QBMXp/1UjKHuc8prhxvzBl+tP 2RWOFPF430VIfZQ8Cttf3hgM2q/2x3o= ARC-Authentication-Results: i=1; imf04.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b="B/c/+WNY"; spf=pass (imf04.hostedemail.com: domain of baohua@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=baohua@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 8BC4341339; Sun, 26 Jul 2026 01:30:02 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7B3B41F00A3D; Sun, 26 Jul 2026 01:29:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785029402; bh=9jhQTuuPD9KwcoX/z0WxrFRGD97WTuKY5ASJ3vGdEAY=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=B/c/+WNYqFuq5bvjJiDUU4Quc1DnVZR4VWTfmaF2VYh+iwj3+SHvs6V3FzzIn9pOx ZL4kZPsoiwy34n9G4rD4Luj9U28lBptb4feHZtkaLaliCIDwisAaaAw6iQQa+gW/wT 3w4/Tgv9gUuITSL9LSw4xGx/V8IALyw+zYoHBVtnE4NldU9UkokKt232OZiWjFBNkP l/ZyEIrGXriUhJviR6u6WWYbjhrBD8gXVcTnWMNBi+k/LMtawyM6cW/U7sQ87n2N9r bijwzqWyxeOgEmmcUePFVzL+703xQwK9zIo7oEIxPssrGjJaYFPe5r7L5mW1IZrTeQ kgTXl+0172iXg== From: "Barry Song (Xiaomi)" To: akpm@linux-foundation.org, linux-mm@kvack.org Cc: hannes@cmpxchg.org, david@kernel.org, mhocko@kernel.org, qi.zheng@linux.dev, shakeel.butt@linux.dev, ljs@kernel.org, kasong@tencent.com, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, linux-kernel@vger.kernel.org, lyugaofei@xiaomi.com, stevensd@chromium.org, Barry Song Subject: [RFC PATCH 3/4] mm: mglru: run aging when pages are severely imbalanced across gens Date: Sun, 26 Jul 2026 09:29:45 +0800 Message-Id: <20260726012946.18684-4-baohua@kernel.org> X-Mailer: git-send-email 2.39.3 (Apple Git-146) In-Reply-To: <20260726012946.18684-1-baohua@kernel.org> References: <20260726012946.18684-1-baohua@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 312F140009 X-Stat-Signature: zzjn78t5zi8oihx331kecgfto8adqura X-HE-Tag: 1785029403-147526 X-HE-Meta: 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 V+SE6rYh YiQYPVJ9j+HligSFdH3byYdiLoCwLsaJxyjEYzI/16/1+Rd21O8YDkWpgRq2D++JL3Wy/NFD/FIII95DcFOxHQUNNOgYrBBHdINt406dXz9lCUHkkgTMKcV0cvF+fwNNfIhNJtnW62korX/lyS+Pwm6sTtOVwl9u5N+yk5XThUVyA8owOklud4JYGLSCTK0X1fbltetdsF7MBIQCtbdQeymzVvNEa053NGPxmk09rInz+BY2jENQ/+qLxLfSX1BdcCj0Y Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: lyugaofei This partially restores the reclaim behavior introduced in Yu Zhao's initial MGLRU commit, ac35a4902370 ("mm: multi-gen LRU: minimal implementation"): /* * It's also ideal to spread pages out evenly, i.e., 1/(MIN_NR_GENS+1) * of the total number of pages for each generation. A reasonable range * for this average portion is [1/MIN_NR_GENS, 1/(MIN_NR_GENS+2)]. The * aging cares about the upper bound of hot pages, while the eviction * cares about the lower bound of cold pages. */ if (young * MIN_NR_GENS > total) return true; if (old * (MIN_NR_GENS + 2) < total) return true; But with a stricter condition: the youngest gen must have at least four times as many folios as the oldest. This helps keep folios of the preferred type distributed across the reclaimable gens. Signed-off-by: lyugaofei Co-developed-by: Barry Song (Xiaomi) Signed-off-by: Barry Song (Xiaomi) --- mm/vmscan.c | 34 +++++++++++++++++++++++++++++++++- 1 file changed, 33 insertions(+), 1 deletion(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index 4f3a375de86e..9aac4febc206 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -4963,9 +4963,37 @@ static int evict_folios(unsigned long nr_to_scan, struct lruvec *lruvec, return scanned; } +static bool lru_gen_imbalanced(struct lruvec *lruvec, int type, + unsigned long max_seq, unsigned long min_seq, + int swappiness) +{ + struct lru_gen_folio *lrugen = &lruvec->lrugen; + unsigned long young = 0, old = 0, seq; + + if (swappiness == MIN_SWAPPINESS || swappiness > MAX_SWAPPINESS) + return false; + + for (seq = min_seq; seq <= max_seq; seq++) { + int gen = lru_gen_from_seq(seq); + unsigned long size = 0; + int zone; + + gen = lru_gen_from_seq(seq); + for (zone = 0; zone < MAX_NR_ZONES; zone++) + size += max(READ_ONCE(lrugen->nr_pages[gen][type][zone]), 0L); + + if (seq + MIN_NR_GENS > max_seq) + young += size; + else + old += size; + } + return young > old * 4; +} + static bool should_run_aging(struct lruvec *lruvec, unsigned long max_seq, struct scan_control *sc, int swappiness) { + int type = get_type_to_scan(lruvec, swappiness); DEFINE_MIN_SEQ(lruvec); /* have to run aging, since eviction is not possible anymore */ @@ -4977,7 +5005,11 @@ static bool should_run_aging(struct lruvec *lruvec, unsigned long max_seq, return false; /* better to run aging even though eviction is still possible */ - return evictable_min_seq(min_seq, swappiness) + MIN_NR_GENS == max_seq; + if (evictable_min_seq(min_seq, swappiness) + MIN_NR_GENS == max_seq) + return true; + + /* Run aging if the preferred type is severely imbalanced across gens */ + return lru_gen_imbalanced(lruvec, type, max_seq, min_seq[type], swappiness); } static long get_nr_to_scan(struct lruvec *lruvec, struct scan_control *sc, -- 2.39.3 (Apple Git-146)