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[18.181.137.102]) by smtp.gmail.com with ESMTPSA id p10-20020a637f4a000000b00373a2760775sm10878743pgn.2.2022.03.06.23.41.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 06 Mar 2022 23:41:17 -0800 (PST) From: Hyeonggon Yoo <42.hyeyoo@gmail.com> To: linux-mm@kvack.org Cc: Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Vlastimil Babka , Marco Elver , Matthew WilCox , Roman Gushchin , linux-kernel@vger.kernel.org, 42.hyeyoo@gmail.com Subject: [PATCH v3 1/2] mm/slub: limit number of node partial slabs only in cache creation Date: Mon, 7 Mar 2022 07:40:55 +0000 Message-Id: <20220307074057.902222-2-42.hyeyoo@gmail.com> X-Mailer: git-send-email 2.33.1 In-Reply-To: <20220307074057.902222-1-42.hyeyoo@gmail.com> References: <20220307074057.902222-1-42.hyeyoo@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" SLUB sets number of minimum partial slabs for node (min_partial) using set_min_partial(). SLUB holds at least min_partial slabs even if they're empty to avoid excessive use of page allocator. set_min_partial() limits value of min_partial limits value of min_partial MIN_PARTIAL and MAX_PARTIAL. As set_min_partial() can be called by min_partial_store() too, Only limit value of min_partial in kmem_cache_open() so that it can be changed to value that a user wants. [ rientjes@google.com: Fold set_min_partial() into its callers ] Signed-off-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> Reviewed-by: Vlastimil Babka --- mm/slub.c | 14 +++----------- 1 file changed, 3 insertions(+), 11 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index 261474092e43..1ce09b0347ad 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -4000,15 +4000,6 @@ static int init_kmem_cache_nodes(struct kmem_cache *= s) return 1; } =20 -static void set_min_partial(struct kmem_cache *s, unsigned long min) -{ - if (min < MIN_PARTIAL) - min =3D MIN_PARTIAL; - else if (min > MAX_PARTIAL) - min =3D MAX_PARTIAL; - s->min_partial =3D min; -} - static void set_cpu_partial(struct kmem_cache *s) { #ifdef CONFIG_SLUB_CPU_PARTIAL @@ -4215,7 +4206,8 @@ static int kmem_cache_open(struct kmem_cache *s, slab= _flags_t flags) * The larger the object size is, the more slabs we want on the partial * list to avoid pounding the page allocator excessively. */ - set_min_partial(s, ilog2(s->size) / 2); + s->min_partial =3D min_t(unsigned long, MAX_PARTIAL, ilog2(s->size) / 2); + s->min_partial =3D max_t(unsigned long, MIN_PARTIAL, s->min_partial); =20 set_cpu_partial(s); =20 @@ -5396,7 +5388,7 @@ static ssize_t min_partial_store(struct kmem_cache *s= , const char *buf, if (err) return err; =20 - set_min_partial(s, min); + s->min_partial =3D min; return length; } SLAB_ATTR(min_partial); --=20 2.33.1 From nobody Tue Jun 23 11:15:09 2026 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 709CFC433F5 for ; Mon, 7 Mar 2022 07:41:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235815AbiCGHmU (ORCPT ); Mon, 7 Mar 2022 02:42:20 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38114 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235879AbiCGHmP (ORCPT ); Mon, 7 Mar 2022 02:42:15 -0500 Received: from mail-pj1-x1029.google.com (mail-pj1-x1029.google.com [IPv6:2607:f8b0:4864:20::1029]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A9F9A3968C for ; Sun, 6 Mar 2022 23:41:21 -0800 (PST) Received: by mail-pj1-x1029.google.com with SMTP id 15-20020a17090a098f00b001bef0376d5cso13346676pjo.5 for ; Sun, 06 Mar 2022 23:41:21 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=ZGMJZ/gEuZAOoC4B+YmBrsXSs5tkxREQEs5olVeuJaw=; b=eNjzzbpeQLIHlMcaIfbd03vqkymRW54NmATbFQGI0ZOTyDPJdiACVVdKNEi1YC2iBx Kos1SPh67kgKR1PTCYPNoIpha5uq8aC0hWlgiDLlJRj5G3fj8thV6sgleQRaXU2y+fkg xlTUb6Se1WzzCia6dF+zHVlk15DzrQ85QqhH3edD/tb3yg/J12FPzt/cx9lpC/H57CjS y4jrpgwed4+dyGsIc35Soi6JEBEdBlxNF1sx9pImqtJnr6Sr3ug99Wj3HMPOmy8pVAzs pVYUS496lotEZ2NIqOl7SJivDgCUqAKPU4+N97Jrsfv4GaAgErxfDWt7yBp86Qztrl4k vNUQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=ZGMJZ/gEuZAOoC4B+YmBrsXSs5tkxREQEs5olVeuJaw=; b=UzIwL7E4kdhwtQ7KB8k4cOXPDPYXs/MeaVjtDCVtCTbcUL3q70zZJb98cOf3vNWwUm p4P6q0CDGeZdR2/lq4kLZ00apC5Eo9ya28ZdrvG8RM3Al8ys9DynHZLNVgEY44cbTVCS 71u6tl69BSwi2rtxeMFXUMcVmnAMlErosWTnGmulCIX8yuNm796DXUuVyvZ1eUoqjGh4 pb/ojWX3LYeONyJzJn27DNaI5JCyQvsDSMMXrWJy16H2efViUXkft5c/zh6ISBqldZd/ BDZI8EUXFvnxC3QzKBa4/S+oFiJQk6CD00gFqi+bDcIIoB97so7OsQoYUixRQTs0VkzB 44cg== X-Gm-Message-State: AOAM530jpVbIB6jPiW+5Kz2/MjuW9Z1vBEF6zCeb0iI1aGQKGfs83GGd kIuFNRjcQMyyduCrKjG1sDA= X-Google-Smtp-Source: ABdhPJwaQxVqrVx8gsxT5/Suk/f0ODcodwq9e9CauZGzxkmOIohCLXMIb+Gr/YK3xnaDruiSupmM8A== X-Received: by 2002:a17:90b:3e88:b0:1bf:3bd0:4b5f with SMTP id rj8-20020a17090b3e8800b001bf3bd04b5fmr11096426pjb.106.1646638881181; Sun, 06 Mar 2022 23:41:21 -0800 (PST) Received: from ip-172-31-19-208.ap-northeast-1.compute.internal (ec2-18-181-137-102.ap-northeast-1.compute.amazonaws.com. [18.181.137.102]) by smtp.gmail.com with ESMTPSA id p10-20020a637f4a000000b00373a2760775sm10878743pgn.2.2022.03.06.23.41.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 06 Mar 2022 23:41:20 -0800 (PST) From: Hyeonggon Yoo <42.hyeyoo@gmail.com> To: linux-mm@kvack.org Cc: Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Vlastimil Babka , Marco Elver , Matthew WilCox , Roman Gushchin , linux-kernel@vger.kernel.org, 42.hyeyoo@gmail.com Subject: [PATCH v3 2/2] mm/slub: refactor deactivate_slab() Date: Mon, 7 Mar 2022 07:40:56 +0000 Message-Id: <20220307074057.902222-3-42.hyeyoo@gmail.com> X-Mailer: git-send-email 2.33.1 In-Reply-To: <20220307074057.902222-1-42.hyeyoo@gmail.com> References: <20220307074057.902222-1-42.hyeyoo@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Simplify deactivate_slab() by unlocking n->list_lock and retrying cmpxchg_double() when cmpxchg_double() fails, and perform add_{partial,full} only when it succeed. Releasing and taking n->list_lock again here is not harmful as SLUB avoids deactivating slabs as much as possible. [ vbabka@suse.cz: perform add_{partial,full} when cmpxchg_double() succeed. count deactivating full slabs even if debugging flag is not set. ] Signed-off-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> Reviewed-by: Roman Gushchin Reviewed-by: Vlastimil Babka --- mm/slub.c | 91 +++++++++++++++++++++++-------------------------------- 1 file changed, 38 insertions(+), 53 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index 1ce09b0347ad..f0cb9d0443ac 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2348,10 +2348,10 @@ static void init_kmem_cache_cpus(struct kmem_cache = *s) static void deactivate_slab(struct kmem_cache *s, struct slab *slab, void *freelist) { - enum slab_modes { M_NONE, M_PARTIAL, M_FULL, M_FREE }; + enum slab_modes { M_NONE, M_PARTIAL, M_FULL, M_FREE, M_FULL_NOLIST }; struct kmem_cache_node *n =3D get_node(s, slab_nid(slab)); - int lock =3D 0, free_delta =3D 0; - enum slab_modes l =3D M_NONE, m =3D M_NONE; + int free_delta =3D 0; + enum slab_modes mode =3D M_NONE; void *nextfree, *freelist_iter, *freelist_tail; int tail =3D DEACTIVATE_TO_HEAD; unsigned long flags =3D 0; @@ -2393,14 +2393,10 @@ static void deactivate_slab(struct kmem_cache *s, s= truct slab *slab, * Ensure that the slab is unfrozen while the list presence * reflects the actual number of objects during unfreeze. * - * We setup the list membership and then perform a cmpxchg - * with the count. If there is a mismatch then the slab - * is not unfrozen but the slab is on the wrong list. - * - * Then we restart the process which may have to remove - * the slab from the list that we just put it on again - * because the number of objects in the slab may have - * changed. + * We first perform cmpxchg holding lock and insert to list + * when it succeed. If there is mismatch then the slab is not + * unfrozen and number of objects in the slab may have changed. + * Then release lock and retry cmpxchg again. */ redo: =20 @@ -2420,61 +2416,50 @@ static void deactivate_slab(struct kmem_cache *s, s= truct slab *slab, new.frozen =3D 0; =20 if (!new.inuse && n->nr_partial >=3D s->min_partial) - m =3D M_FREE; + mode =3D M_FREE; else if (new.freelist) { - m =3D M_PARTIAL; - if (!lock) { - lock =3D 1; - /* - * Taking the spinlock removes the possibility that - * acquire_slab() will see a slab that is frozen - */ - spin_lock_irqsave(&n->list_lock, flags); - } - } else { - m =3D M_FULL; - if (kmem_cache_debug_flags(s, SLAB_STORE_USER) && !lock) { - lock =3D 1; - /* - * This also ensures that the scanning of full - * slabs from diagnostic functions will not see - * any frozen slabs. - */ - spin_lock_irqsave(&n->list_lock, flags); - } - } - - if (l !=3D m) { - if (l =3D=3D M_PARTIAL) - remove_partial(n, slab); - else if (l =3D=3D M_FULL) - remove_full(s, n, slab); + mode =3D M_PARTIAL; + /* + * Taking the spinlock removes the possibility that + * acquire_slab() will see a slab that is frozen + */ + spin_lock_irqsave(&n->list_lock, flags); + } else if (kmem_cache_debug_flags(s, SLAB_STORE_USER)) { + mode =3D M_FULL; + /* + * This also ensures that the scanning of full + * slabs from diagnostic functions will not see + * any frozen slabs. + */ + spin_lock_irqsave(&n->list_lock, flags); + } else + mode =3D M_FULL_NOLIST; =20 - if (m =3D=3D M_PARTIAL) - add_partial(n, slab, tail); - else if (m =3D=3D M_FULL) - add_full(s, n, slab); - } =20 - l =3D m; if (!cmpxchg_double_slab(s, slab, old.freelist, old.counters, new.freelist, new.counters, - "unfreezing slab")) + "unfreezing slab")) { + if (mode =3D=3D M_PARTIAL || mode =3D=3D M_FULL) + spin_unlock_irqrestore(&n->list_lock, flags); goto redo; + } =20 - if (lock) - spin_unlock_irqrestore(&n->list_lock, flags); =20 - if (m =3D=3D M_PARTIAL) + if (mode =3D=3D M_PARTIAL) { + add_partial(n, slab, tail); + spin_unlock_irqrestore(&n->list_lock, flags); stat(s, tail); - else if (m =3D=3D M_FULL) - stat(s, DEACTIVATE_FULL); - else if (m =3D=3D M_FREE) { + } else if (mode =3D=3D M_FREE) { stat(s, DEACTIVATE_EMPTY); discard_slab(s, slab); stat(s, FREE_SLAB); - } + } else if (mode =3D=3D M_FULL) { + add_full(s, n, slab); + spin_unlock_irqrestore(&n->list_lock, flags); + stat(s, DEACTIVATE_FULL); + } else if (mode =3D=3D M_FULL_NOLIST) + stat(s, DEACTIVATE_FULL); } =20 #ifdef CONFIG_SLUB_CPU_PARTIAL --=20 2.33.1