From nobody Fri Dec 19 19:01:23 2025 Received: from mail-oa1-f52.google.com (mail-oa1-f52.google.com [209.85.160.52]) (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 01E1D18054 for ; Fri, 22 Dec 2023 10:24:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="EkBUT+4j" Received: by mail-oa1-f52.google.com with SMTP id 586e51a60fabf-203fed05a31so1116439fac.0 for ; Fri, 22 Dec 2023 02:24:12 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1703240652; x=1703845452; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:reply-to:references :in-reply-to:message-id:date:subject:cc:to:from:from:to:cc:subject :date:message-id:reply-to; bh=gsAcvd86KuP2ISw06xLpP7WDqEO9VY9n54CovJHHIls=; b=EkBUT+4jVO5UYs3Cgaf5ikrKSKqM1Oknk/QO7sd1R+9evYo9hRvjSM4gUcGwIaf67Z KYNk/kK33+jPs/LfnTPRKvkUVFOoDtWL2q5g14lw+jEFaW7u8NCBu5dynJ3Tbh8UYQgN wdLA7wxYhzIyRGZFyQVMTgP64p3CDSmsr//2ZbfqIOM02ngsX20NqA13h3zTAaXvOYar PZIF7seYGGElVd0yIPEFQ4GlTvnjjM7LaBuAKcLF//y4Z/BnqGyiWRLayq+dHI+K7ZFT u6DZcnXKevdFgBlIfUg6IN23b5auMO7RMax7C+1J9tDmCW6jsz7bVUDMs89huYmKWy2o +FGA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1703240652; x=1703845452; h=content-transfer-encoding:mime-version:reply-to:references :in-reply-to:message-id:date:subject:cc:to:from:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=gsAcvd86KuP2ISw06xLpP7WDqEO9VY9n54CovJHHIls=; b=nJjMtva++m0JBfDBI/dtxuHxDFLQfP5V7JQ7hVlaD/9ZK1Rmud2leFXg9DuHu2soJx pJ3OX8f6VVED5aPVJotR+1iw6Y2BEbPo24RmfJj7Y/uY/Jya5fTK+TVBkqVqEeI9x3Fx MsEXi2QIZxhttWO3VMOd9ae5qknpMERmqYBzhuc0nr7/TQMhbUHUiyroCtpawS1CRcKI g9Z4FMJUstIhav9VRMZybrQRQu6BlCOiD782psM6nKjL7/65jiI3QTSaKPqrHK8oNRt1 cBx+kBD+Yew5LEMHYl4MPbbTIDufUgJ5U3yiwoENeUyAoE1+LbaiAz30EdrlI39pFt44 Qiew== X-Gm-Message-State: AOJu0YzJ3zl1lMTyD9NPmNS+7dt+N1dGk6JNbnXqrmWS8y0j+3IjKHsh NC+KRHHxWIkVpULFgjQKYWI= X-Google-Smtp-Source: AGHT+IFM08JVkja56Id51LMPVYml7/oIhHyVGlp94LC9R8zx3T0/LUwfVjdY7Ob42uuEZ9jE1hgJMg== X-Received: by 2002:a05:6870:ce0b:b0:204:5455:c44b with SMTP id xc11-20020a056870ce0b00b002045455c44bmr41106oab.107.1703240651957; Fri, 22 Dec 2023 02:24:11 -0800 (PST) Received: from KASONG-MB2.tencent.com ([103.7.29.31]) by smtp.gmail.com with ESMTPSA id gx1-20020a056a001e0100b006d9912e9a77sm364074pfb.6.2023.12.22.02.24.09 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Fri, 22 Dec 2023 02:24:11 -0800 (PST) From: Kairui Song To: linux-mm@kvack.org Cc: Andrew Morton , Yu Zhao , linux-kernel@vger.kernel.org, Kairui Song Subject: [PATCH 2/3] mm, lru_gen: move pages in bulk when aging Date: Fri, 22 Dec 2023 18:22:54 +0800 Message-ID: <20231222102255.56993-3-ryncsn@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20231222102255.56993-1-ryncsn@gmail.com> References: <20231222102255.56993-1-ryncsn@gmail.com> Reply-To: Kairui Song 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: Kairui Song Another overhead of aging is page moving. Actually, in most cases, pages are being moved to the same gen after folio_inc_gen is called, especially the protected pages. So it's better to move them in bulk. This also has a good effect on LRU ordering. Currently when MGLRU ages, it walks the LRU backward, and the protected pages are moved to the tail of newer gen one by one, which reverses the order of pages in LRU. Moving them in batches can help keep their order, only in a small scope though due to the scan limit of MAX_LRU_BATCH pages. After this commit, we can see a performance gain: Tested in a 4G memcg on a EPYC 7K62 with: memcached -u nobody -m 16384 -s /tmp/memcached.socket \ -a 0766 -t 16 -B binary & memtier_benchmark -S /tmp/memcached.socket \ -P memcache_binary -n allkeys \ --key-minimum=3D1 --key-maximum=3D16000000 -d 1024 \ --ratio=3D1:0 --key-pattern=3DP:P -c 2 -t 16 --pipeline 8 -x 6 Average result of 18 test runs: Before: 44017.78 Ops/sec After patch 1-2: 44810.01 Ops/sec (+1.8%) Signed-off-by: Kairui Song --- mm/vmscan.c | 84 ++++++++++++++++++++++++++++++++++++++++++++--------- 1 file changed, 71 insertions(+), 13 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index e3b4797b9729..af1266129c1b 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -3102,9 +3102,46 @@ static int folio_update_gen(struct folio *folio, int= gen) */ struct gen_update_batch { int delta[MAX_NR_GENS]; + struct folio *head, *tail; }; =20 -static void lru_gen_update_batch(struct lruvec *lruvec, bool type, int zon= e, +static void inline lru_gen_inc_bulk_finish(struct lru_gen_folio *lrugen, + int bulk_gen, bool type, int zone, + struct gen_update_batch *batch) +{ + if (!batch->head) + return; + + list_bulk_move_tail(&lrugen->folios[bulk_gen][type][zone], + &batch->head->lru, + &batch->tail->lru); + + batch->head =3D NULL; +} + +/* + * When aging, protected pages will go to the tail of the same higher + * gen, so the can be moved in batches. Besides reduced overhead, this + * also avoids changing their LRU order in a small scope. + */ +static void inline lru_gen_try_inc_bulk(struct lru_gen_folio *lrugen, stru= ct folio *folio, + int bulk_gen, int gen, bool type, int zone, + struct gen_update_batch *batch) +{ + /* + * If folio not moving to the bulk_gen, it's raced with promotion + * so it need to go to the head of another LRU. + */ + if (bulk_gen !=3D gen) + list_move(&folio->lru, &lrugen->folios[gen][type][zone]); + + if (!batch->head) + batch->tail =3D folio; + + batch->head =3D folio; +} + +static void lru_gen_update_batch(struct lruvec *lruvec, int bulk_gen, bool= type, int zone, struct gen_update_batch *batch) { int gen; @@ -3112,6 +3149,8 @@ static void lru_gen_update_batch(struct lruvec *lruve= c, bool type, int zone, struct lru_gen_folio *lrugen =3D &lruvec->lrugen; enum lru_list lru =3D type ? LRU_INACTIVE_FILE : LRU_INACTIVE_ANON; =20 + lru_gen_inc_bulk_finish(lrugen, bulk_gen, type, zone, batch); + for (gen =3D 0; gen < MAX_NR_GENS; gen++) { int delta =3D batch->delta[gen]; =20 @@ -3705,6 +3744,7 @@ static bool inc_min_seq(struct lruvec *lruvec, int ty= pe, bool can_swap) struct gen_update_batch batch =3D { }; struct lru_gen_folio *lrugen =3D &lruvec->lrugen; int new_gen, old_gen =3D lru_gen_from_seq(lrugen->min_seq[type]); + int bulk_gen =3D (old_gen + 1) % MAX_NR_GENS; =20 if (type =3D=3D LRU_GEN_ANON && !can_swap) goto done; @@ -3712,24 +3752,33 @@ static bool inc_min_seq(struct lruvec *lruvec, int = type, bool can_swap) /* prevent cold/hot inversion if force_scan is true */ for (zone =3D 0; zone < MAX_NR_ZONES; zone++) { struct list_head *head =3D &lrugen->folios[old_gen][type][zone]; + struct folio *prev =3D NULL; =20 - while (!list_empty(head)) { - struct folio *folio =3D lru_to_folio(head); + if (!list_empty(head)) + prev =3D lru_to_folio(head); =20 + while (prev) { + struct folio *folio =3D prev; 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) !=3D type, folio); VM_WARN_ON_ONCE_FOLIO(folio_zonenum(folio) !=3D zone, folio); =20 + if (unlikely(list_is_first(&folio->lru, head))) + prev =3D NULL; + else + prev =3D lru_to_folio(&folio->lru); + new_gen =3D folio_inc_gen(lruvec, folio, false, &batch); - list_move_tail(&folio->lru, &lrugen->folios[new_gen][type][zone]); + lru_gen_try_inc_bulk(lrugen, folio, bulk_gen, new_gen, type, zone, &bat= ch); =20 if (!--remaining) { - lru_gen_update_batch(lruvec, type, zone, &batch); + lru_gen_update_batch(lruvec, bulk_gen, type, zone, &batch); return false; } } - lru_gen_update_batch(lruvec, type, zone, &batch); + + lru_gen_update_batch(lruvec, bulk_gen, type, zone, &batch); } done: reset_ctrl_pos(lruvec, type, true); @@ -4240,7 +4289,7 @@ static int lru_gen_memcg_seg(struct lruvec *lruvec) *************************************************************************= *****/ =20 static bool sort_folio(struct lruvec *lruvec, struct folio *folio, struct = scan_control *sc, - int tier_idx, struct gen_update_batch *batch) + int tier_idx, int bulk_gen, struct gen_update_batch *batch) { bool success; int gen =3D folio_lru_gen(folio); @@ -4283,7 +4332,7 @@ static bool sort_folio(struct lruvec *lruvec, struct = folio *folio, struct scan_c int hist =3D lru_hist_from_seq(lrugen->min_seq[type]); =20 gen =3D folio_inc_gen(lruvec, folio, false, batch); - list_move_tail(&folio->lru, &lrugen->folios[gen][type][zone]); + lru_gen_try_inc_bulk(lrugen, folio, bulk_gen, gen, type, zone, batch); =20 WRITE_ONCE(lrugen->protected[hist][type][tier - 1], lrugen->protected[hist][type][tier - 1] + delta); @@ -4293,7 +4342,7 @@ static bool sort_folio(struct lruvec *lruvec, struct = folio *folio, struct scan_c /* ineligible */ if (zone > sc->reclaim_idx || skip_cma(folio, sc)) { gen =3D folio_inc_gen(lruvec, folio, false, batch); - list_move_tail(&folio->lru, &lrugen->folios[gen][type][zone]); + lru_gen_try_inc_bulk(lrugen, folio, bulk_gen, gen, type, zone, batch); return true; } =20 @@ -4367,11 +4416,16 @@ static int scan_folios(struct lruvec *lruvec, struc= t scan_control *sc, LIST_HEAD(moved); int skipped_zone =3D 0; struct gen_update_batch batch =3D { }; + int bulk_gen =3D (gen + 1) % MAX_NR_GENS; int zone =3D (sc->reclaim_idx + i) % MAX_NR_ZONES; struct list_head *head =3D &lrugen->folios[gen][type][zone]; + struct folio *prev =3D NULL; =20 - while (!list_empty(head)) { - struct folio *folio =3D lru_to_folio(head); + if (!list_empty(head)) + prev =3D lru_to_folio(head); + + while (prev) { + struct folio *folio =3D prev; int delta =3D folio_nr_pages(folio); =20 VM_WARN_ON_ONCE_FOLIO(folio_test_unevictable(folio), folio); @@ -4380,8 +4434,12 @@ static int scan_folios(struct lruvec *lruvec, struct= scan_control *sc, VM_WARN_ON_ONCE_FOLIO(folio_zonenum(folio) !=3D zone, folio); =20 scanned +=3D delta; + if (unlikely(list_is_first(&folio->lru, head))) + prev =3D NULL; + else + prev =3D lru_to_folio(&folio->lru); =20 - if (sort_folio(lruvec, folio, sc, tier, &batch)) + if (sort_folio(lruvec, folio, sc, tier, bulk_gen, &batch)) sorted +=3D delta; else if (isolate_folio(lruvec, folio, sc)) { list_add(&folio->lru, list); @@ -4401,7 +4459,7 @@ static int scan_folios(struct lruvec *lruvec, struct = scan_control *sc, skipped +=3D skipped_zone; } =20 - lru_gen_update_batch(lruvec, type, zone, &batch); + lru_gen_update_batch(lruvec, bulk_gen, type, zone, &batch); =20 if (!remaining || isolated >=3D MIN_LRU_BATCH) break; --=20 2.43.0