From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794342036; b=g0gDZwnvZHSI8/4kUjVuFowlj0z5Ey8DF/ZWJVTJ6tgf7epCG6dKU+89Q+9dyE9Wc11p unCAi5jv22Rsw+1m05lCIRejIf0Ubk67lmDC6J/HWuxs/3Vzam6LKqBDjMijTm9SY4lmL h2Fq1UN0x8qiTgYTvGly5KNtfG0vL7gnyVZ5lqisMf2ItIn/hYaxWsc6ogQCzWO89Gqkw l+8ZKMdGOMIwfxYNPUf2KoQPyIJe+GlFmzd9Da52cZuf1eirGoDEAy6gBJ3gCw33DEz13 LwBTKjjwsMrJ7C5OVgIgMMpShqJs7A+pl018QPhjsMiTq7G6tBZ1+SbdTQjb1Y2qd5w== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794342036; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-Id:X-Mailer: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=HGHMI3Nx0h6Lh52y7eI24JzQXy85XaR4p0stT74UYFg=; b=LWrbSdXLdviOmscCXsos7kcplfpzQiRKElzTtN+3aXXf8Iz21q8yPXHbFcZ5LTq8m4I+ bBeS5apERvaJd+0X1g/ZHjmihTwjbg8EpQ/YcrgKdVZLEJ243PGx2aQ3ZWRnDeTBUqPdz ttfnuEsZeIHxHeQkFlSAdHqotAUd+KoUSjFfbl9hh8ccxf09XCFFiIBI4snpedvoCz45N 9q+mw+sR9DsaUO5hAAajSlr4+9Dbjx37KUqQkDq9B5LgSabnUlGtKrqMmGbBoA4acN7M7 uOUfU232j6EfZX2s5TGEyKP9VjFIQ3woWNGNFHI4UPykI7A/xkHn8cu3su4S+zFcIGQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=UxXWpp96; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B189E60A3825 for ; Tue, 10 Nov 2026 20:20:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=UxXWpp96 Received: by smtp.kernel.org (Postfix) with ESMTPSA id CE3EB1F008A1; Tue, 10 Nov 2026 20:20:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794342035; bh=HGHMI3Nx0h6Lh52y7eI24JzQXy85XaR4p0stT74UYFg=; h=From:To:Cc:Subject:Date; b=UxXWpp966az3XWO29pH4Q+roZVRThHYA2/Tao0GwSWbdkwc7/jL9Da3aUVo58Y0B4 p7e0X992VeUGG+M2yTD57RquvLM64rnIehDRy6C39oQ58adZ/Z1DxlBodlTj1oOoG8 KNFAj78s4zYYB3h5elSxcxgDwpQ4Rr7dL/magEz2khgzZnMRfC3ppsszOaz2GCgOKF UDKByDz5nY5rD+gWeswqcMx0J40It4c24YSgHbZdGIQ70niQD7NKfuYKq5LbEMUq/C J6IOswUSEvHe1hP3sm+yvCt5HZZex6vsFcyCsdn/3n383IaTezsRjkUBr/hVqsKYlC RZog/9eV1umWg== From: "Barry Song (Xiaomi)" To: akpm@linux-foundation.org, linux-mm@kvack.org Cc: axelrasmussen@google.com, baolin.wang@linux.alibaba.com, baoquan.he@linux.dev, hannes@cmpxchg.org, hui.zhu@linux.dev, kasong@tencent.com, kunwu.chan@gmail.com, liam@infradead.org, lianux.mm@gmail.com, linux-kernel@vger.kernel.org, liuxiang.277@bytedance.com, lyugaofei@xiaomi.com, mhocko@kernel.org, mhocko@suse.com, qi.zheng@linux.dev, ridong.chen@linux.dev, rppt@kernel.org, ryncsn@gmail.com, shakeel.butt@linux.dev, surenb@google.com, wangzicheng@honor.com, weixugc@google.com, yuanchu@google.com, zhangbo56@xiaomi.com, zhuhui@kylinos.cn, sidchintamaneni@gmail.com, "Barry Song (Xiaomi)" Subject: [PATCH v6 00/15] mm: mglru: fix swappiness behavior Date: Wed, 11 Nov 2026 04:20:10 +0800 Message-Id: <20261110202025.25736-1-baohua@kernel.org> X-Mailer: git-send-email 2.39.3 (Apple Git-146) X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Classic LRU respects swappiness, while MGLRU only weakly honors it when selecting the scan type. The fallback logic can easily override the bias established by get_type_to_scan(). As a result, swappiness has a much smaller overall impact when changing from 1 to 200, as shown by the data presented later in this cover letter. In this patchset, patches 1-8 from Kairui introduce a model that uses refaults to determine nr_to_scan[] for both file and anon in MGLRU. For each reclaim operation, we calculate how many file and anon folios to scan, similar to CLRU, rather than relying on get_type_to_scan() and fallback mechanisms to decide what to reclaim, which have proven rather unreliable in honoring swappiness. This model also allows scanning and reclaiming from the two youngest generations, including the youngest generation itself. This can help resolve OOM situations[1] and reduce the need for aging. As Kairui mentioned, the OOM reproducer was demonstrated previously [2], and that series was merged in v7 [3]. The problem was largely alleviated as described, but not completely fixed. Under higher memory pressure, the system could still hit OOM. Before this series, Kairui could still reproduce OOM after hundreds of iterations. With the fixing patch in this series applied, the problem no longer occurs. Patch 9 from Barry fixes a cold/hot inversion exacerbated by patches 1–8 (which also exists in mainline) and improves reclaim efficiency. Patches 10-14 from Gaofei and Barry optimize aging based on folio distribution imbalance and improve reclaim behavior at extreme swappiness values such as 1 and 200. Patch 15 from Bo Zhang addresses the GFP_NOIO issue in MGLRU. After the patchset, the results track CLRU across the full swappiness range (see table below), with more file scanning at low swappiness and more anon scanning at high swappiness. After the patchset, the results track CLRU across the full swappiness range (see table below), with more file scanning at low swappiness and more anon scanning at high swappiness. pgsteal_file swappiness CLRU MGLRU MGLRU+patches 1 6,620,680 745,968 7,200,993 36 807,807 508,974 536,154 71 553,144 417,700 430,877 106 402,880 402,474 360,526 141 240,293 337,797 305,636 176 187,682 330,045 229,553 200 0 343,949 0 pgsteal_anon swappiness CLRU MGLRU MGLRU+patches 1 4,436,199 2,671,934 5,362,520 36 2,858,117 3,032,747 2,743,947 71 3,042,392 2,827,735 3,204,163 106 3,292,622 3,184,314 3,150,825 141 3,612,869 2,999,000 3,489,850 176 3,827,154 3,134,127 3,708,769 200 13,825,283 3,269,753 14,403,938 pgscan_file swappiness CLRU MGLRU MGLRU+patches 1 11,853,625 877,311 14,766,000 36 1,016,826 582,783 617,127 71 662,823 474,772 478,840 106 496,374 451,285 377,093 141 277,109 382,604 322,931 176 206,261 372,059 233,651 200 0 393,608 0 pgscan_anon swappiness CLRU MGLRU MGLRU+patches 1 20,804,386 5,847,747 7,501,764 36 17,830,330 6,740,075 6,197,057 71 18,357,293 6,126,194 7,074,152 106 19,938,920 6,431,355 7,555,448 141 19,609,579 5,997,762 9,211,098 176 21,612,749 6,071,032 11,058,694 200 44,776,474 6,544,125 29,993,141 refault_file swappiness CLRU MGLRU MGLRU+patches 1 6,523,070 667,302 7,122,634 36 722,110 431,585 459,100 71 477,062 340,241 352,834 106 327,610 324,747 283,673 141 161,827 265,959 230,350 176 115,551 258,515 162,880 200 0 268,049 0 refault_anon swappiness CLRU MGLRU MGLRU+patches 1 867,728 552,829 1,408,397 36 419,635 657,745 555,600 71 536,299 611,345 701,640 106 580,742 693,689 692,630 141 706,151 639,850 817,103 176 706,499 685,086 893,704 200 4,693,850 733,273 5,462,849 With a normal swappiness setting (without extreme bias), I see almost no noticeable performance difference between the two versions. For example, with `swappiness=60`, the average results over 5 rounds are: metric W/o patch W/ patch real 1m49.273s 1m49.269s user 25m33.186s 25m33.695s sys 3m41.851s 3m40.779s [1] https://github.com/ryncsn/emm-test-project/tree/master/file-anon-mix-pressure [2] https://lore.kernel.org/all/20260318-mglru-reclaim-v1-0-2c46f9eb0508@tencent.com/ [3] https://lore.kernel.org/linux-mm/20260428-mglru-reclaim-v7-0-02fabb92dc43@tencent.com/ v6: * rebase on top of mm-new(a lot of conflicts due to recent active mglru developments); * only count eligible zones below sc->reclaim_idx for lruvec_evictable_size() and lru_gen_imbalanced(); * GFP_NOIO further fixing by Bo Zhang, exclude unreclaimable type in lruvec_evictable_size(). * Add Kunwu's reviewed-by, thanks! * RFC v5 link: https://lore.kernel.org/linux-mm/20261022220203.91911-1-baohua@kernel.org/ RFC v5: * Remove the aging optimizations, which have been merged - thanks for Baolin, Baoqun, Lian Wang, Kairui, Kunwu, Ridong reviewing on this; * Add Kairui's model for determining nr_to_scan[] for both types. * Fix cold/hot inversion for rejected folios - Barry. * Improve and clean up imbalanced aging, and optimize extreme swappiness values of 1 and 200 - Gaofei, Barry. * Address the GFP_NOIO issue in MGLRU - Bo Zhang. * RFC v4 link: https://lore.kernel.org/linux-mm/20260812121658.69965-1-baohua@kernel.org/ RFC v4: * Clean up isolate_folios() based on Baolin's feedback. Thanks! * Further improve isolate_folios() and scan_folios(), including handling of exhausted reclaim types. * Add fixes and performance improvements to inc_min_seq(), and reduce lock contention. * Improve the handling of imbalanced aging and remaining generation-based aging. * RFC v3 link: https://lore.kernel.org/linux-mm/20260731083843.37811-1-baohua@kernel.org/ RFC v3: - Added Ridong's patch of improving isolate_folios() readability; - for lru_gen_imbalanced(), apply some suggestions from Zicheng and Kairui, considering lruvec size and use macro; - drop "mm: mglru: only fall back when reclaim is running at high priority" - mitigate aging for balanced swappiess value(near middle 100) as swappiness bias is less a concern for them; but slightly increased aging overhead might not be good. * RFC v2 link: https://lore.kernel.org/linux-mm/20260726122123.7614-1-baohua@kernel.org/ RFC v2: - Quickly address a few issues raised in the Sashiko comments so reviewers can ignore v1 and review a cleaner version instead. https://sashiko.dev/#/patchset/20260726012946.18684-1-baohua@kernel.org Thanks, Sashiko! Barry Song (Xiaomi) (4): mm/mglru: Avoid placing rejected folios below populated gen mm/mglru: Restrict eviction accounting to eligible zones mm/mglru: Reduce LRU lock contention by shrinking folio batches in inc_min_seq mm/mglru: Make swappiness=1 file reclaim more aggressive Bo Zhang (1): mm/mglru: Avoid scan anon while swapcache is low for GFP_NOIO allocation Kairui Song (8): mm/mglru: report evictable sizes per type mm/mglru: extract lruvec_populated_min_seq() helper mm/mglru: reclaim from the oldest populated gen mm/mglru: lift the forced protection of reclaimer mm/mglru: skip zones above reclaim_idx instead of rotating them mm/mglru: return for unavailable anon reclaim earlier mm/mglru: balance anon and file scan budget by refault rate mm/mglru: lift youngest gen protection for higher priority lyugaofei (2): mm/mglru: Run aging when pages are rare outside the youngest gen mm/mglru: Avoid prolonged anon reclaim with swappiness=200 include/linux/mm_inline.h | 22 +- mm/trace_vmscan.h | 4 +- mm/vmscan.c | 472 +++++++++++++++++++++++++------------- mm/vmscan.h | 5 +- 4 files changed, 334 insertions(+), 169 deletions(-) -- 2.34.1