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DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1698140051; 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=cdvJNGs14r77ax8dSUQgIW9duarJJopRajvvGp2TDMo=; b=LFQxXGGRKgIbWAldNJ1TYZrnkEc0I+pD5nGoJ0Dqwyqt32dcDScSAvf2HkxURKE+MuV4uf VITI/OvMyXtzkGrkQIUB2hTODauxk/xJEPGsyPf7Ow4uqMZV7ixHrnzuwbIKcLr4S5SXvq SpnsSqfJOa1quAz1cL2pg8WHPN5pFGw= 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 v3 7/7] slub: Optimize deactivate_slab() Date: Tue, 24 Oct 2023 09:33:45 +0000 Message-Id: <20231024093345.3676493-8-chengming.zhou@linux.dev> In-Reply-To: <20231024093345.3676493-1-chengming.zhou@linux.dev> References: <20231024093345.3676493-1-chengming.zhou@linux.dev> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 7F4A118000A X-Stat-Signature: hopoewkportfse36kfoojq4zgs9rted5 X-Rspam-User: X-HE-Tag: 1698140052-730424 X-HE-Meta: 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 ZkCP1Cn8 U4foDqb/Pvvi1tthncSmSSJZhSzwx6E4V4xwYzmG8sdp0WKAuqQldLk1myuwHp2MFf4HrTXY/UPwifsGE3y8UHYJ09GyZQNWeAin/t0Jq427kplYQw+OrRRmnoX3AZfD/TjDjzT1eVT8qyZ/ukR5qoQLpqFcKbC+h87jqJgl7HqaKS+biOK9I+R2J5XziTNKQVGAX3L/0wHTDXx/0nmQvLuEWSfbKRMX1U9nOUBTU9f7Fohe7RfwVmfAKmA== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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 last stage if we really 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 486d44421432..64d550e415eb 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2449,10 +2449,8 @@ 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; @@ -2499,58 +2497,40 @@ 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 -- 2.40.1