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[23.128.96.31]) by mx.google.com with ESMTPS id g16-20020a056a000b9000b0068ff659af62si1915688pfj.106.2023.10.17.08.46.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 17 Oct 2023 08:46:15 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.31 as permitted sender) client-ip=23.128.96.31; Authentication-Results: mx.google.com; dkim=pass header.i=@linux.dev header.s=key1 header.b=FTuhEnnd; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.31 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linux.dev Received: from out1.vger.email (depot.vger.email [IPv6:2620:137:e000::3:0]) by morse.vger.email (Postfix) with ESMTP id 4BFCB806E4D0; Tue, 17 Oct 2023 08:46:00 -0700 (PDT) X-Virus-Status: Clean X-Virus-Scanned: clamav-milter 0.103.10 at morse.vger.email Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344241AbjJQPph (ORCPT + 20 others); Tue, 17 Oct 2023 11:45:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45734 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235082AbjJQPp2 (ORCPT ); Tue, 17 Oct 2023 11:45:28 -0400 Received: from out-191.mta1.migadu.com (out-191.mta1.migadu.com [95.215.58.191]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C7E37F7 for ; Tue, 17 Oct 2023 08:45:26 -0700 (PDT) X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1697557525; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Tb71WTBIRi+Tnmk2GZg+a0sbcsGECWTHjBVZ/Kgj+ow=; b=FTuhEnndbqSCtiqr1O7e+RaC5Xz6OtTHQQeyiMhRejvTs1gPYpLuqXRStCw16NBr7Q3k3+ O4RYPhHqfkT5J7H1e8VhHiBdbBs0AckyoX/neMpbkg24WHjGGLBQOELIyx+/BM31Uj3GT8 t6UbHf9+/jBpU1VLbPxe5Kb/sPbBt9o= From: chengming.zhou@linux.dev To: cl@linux.com, penberg@kernel.org Cc: rientjes@google.com, iamjoonsoo.kim@lge.com, akpm@linux-foundation.org, vbabka@suse.cz, roman.gushchin@linux.dev, 42.hyeyoo@gmail.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, chengming.zhou@linux.dev, Chengming Zhou Subject: [RFC PATCH 3/5] slub: Optimize deactivate_slab() Date: Tue, 17 Oct 2023 15:44:37 +0000 Message-Id: <20231017154439.3036608-4-chengming.zhou@linux.dev> In-Reply-To: <20231017154439.3036608-1-chengming.zhou@linux.dev> References: <20231017154439.3036608-1-chengming.zhou@linux.dev> MIME-Version: 1.0 X-Migadu-Flow: FLOW_OUT X-Spam-Status: No, score=-0.8 required=5.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on morse.vger.email Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (morse.vger.email [0.0.0.0]); Tue, 17 Oct 2023 08:46:00 -0700 (PDT) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1780018132579240607 X-GMAIL-MSGID: 1780018132579240607 From: Chengming Zhou Since the introduce of unfrozen slabs on cpu partial list, we don't need to synchronize the slab frozen state under the node list_lock. The caller of deactivate_slab() and the caller of __slab_free() won't manipulate the slab list concurrently. So we can get node list_lock in the stage three if we need to manipulate the slab list in this path. Signed-off-by: Chengming Zhou --- mm/slub.c | 70 ++++++++++++++++++++----------------------------------- 1 file changed, 25 insertions(+), 45 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index 27eac93baa13..5a9711b35c74 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2520,10 +2520,8 @@ 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_FREE, M_FULL_NOLIST }; struct kmem_cache_node *n = get_node(s, slab_nid(slab)); int free_delta = 0; - enum slab_modes mode = M_NONE; void *nextfree, *freelist_iter, *freelist_tail; int tail = DEACTIVATE_TO_HEAD; unsigned long flags = 0; @@ -2570,58 +2568,40 @@ static void deactivate_slab(struct kmem_cache *s, struct slab *slab, * unfrozen and number of objects in the slab may have changed. * Then release lock and retry cmpxchg again. */ -redo: - - old.freelist = READ_ONCE(slab->freelist); - old.counters = READ_ONCE(slab->counters); - VM_BUG_ON(!old.frozen); - - /* Determine target state of the slab */ - new.counters = old.counters; - if (freelist_tail) { - new.inuse -= free_delta; - set_freepointer(s, freelist_tail, old.freelist); - new.freelist = freelist; - } else - new.freelist = old.freelist; + do { + old.freelist = READ_ONCE(slab->freelist); + old.counters = READ_ONCE(slab->counters); + VM_BUG_ON(!old.frozen); + + /* Determine target state of the slab */ + new.counters = old.counters; + new.frozen = 0; + if (freelist_tail) { + new.inuse -= free_delta; + set_freepointer(s, freelist_tail, old.freelist); + new.freelist = freelist; + } else + new.freelist = old.freelist; - new.frozen = 0; + } while (!slab_update_freelist(s, slab, + old.freelist, old.counters, + new.freelist, new.counters, + "unfreezing slab")); + /* + * Stage three: Manipulate the slab list based on the updated state. + */ if (!new.inuse && n->nr_partial >= s->min_partial) { - mode = M_FREE; + stat(s, DEACTIVATE_EMPTY); + discard_slab(s, slab); + stat(s, FREE_SLAB); } else if (new.freelist) { - mode = 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 { - mode = M_FULL_NOLIST; - } - - - if (!slab_update_freelist(s, slab, - old.freelist, old.counters, - new.freelist, new.counters, - "unfreezing slab")) { - if (mode == M_PARTIAL) - spin_unlock_irqrestore(&n->list_lock, flags); - goto redo; - } - - - if (mode == M_PARTIAL) { add_partial(n, slab, tail); spin_unlock_irqrestore(&n->list_lock, flags); stat(s, tail); - } else if (mode == M_FREE) { - stat(s, DEACTIVATE_EMPTY); - discard_slab(s, slab); - stat(s, FREE_SLAB); - } else if (mode == M_FULL_NOLIST) { + } else stat(s, DEACTIVATE_FULL); - } } #ifdef CONFIG_SLUB_CPU_PARTIAL