From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 23D18C433E0 for ; Tue, 2 Mar 2021 09:14:57 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 8245464D74 for ; Tue, 2 Mar 2021 09:14:56 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8245464D74 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=gentwo.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id ECEF18D00EF; Tue, 2 Mar 2021 04:14:55 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id E82058D0063; Tue, 2 Mar 2021 04:14:55 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D970C8D00EF; Tue, 2 Mar 2021 04:14:55 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0002.hostedemail.com [216.40.44.2]) by kanga.kvack.org (Postfix) with ESMTP id C5ACB8D0063 for ; Tue, 2 Mar 2021 04:14:55 -0500 (EST) Received: from smtpin19.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 8DDAD5DDA for ; Tue, 2 Mar 2021 09:14:55 +0000 (UTC) X-FDA: 77874374550.19.DD744A7 Received: from gentwo.de (vmi485042.contaboserver.net [161.97.139.209]) by imf24.hostedemail.com (Postfix) with ESMTP id 4A3A9A0009CE for ; Tue, 2 Mar 2021 09:14:54 +0000 (UTC) Received: by gentwo.de (Postfix, from userid 1001) id C7556B00C98; Tue, 2 Mar 2021 10:14:53 +0100 (CET) Received: from localhost (localhost [127.0.0.1]) by gentwo.de (Postfix) with ESMTP id C5F01B00C5F; Tue, 2 Mar 2021 10:14:53 +0100 (CET) Date: Tue, 2 Mar 2021 10:14:53 +0100 (CET) From: Christoph Lameter To: Xunlei Pang cc: Vlastimil Babka , Wen Yang , Roman Gushchin , Pekka Enberg , Konstantin Khlebnikov , David Rientjes , linux-kernel@vger.kernel.org, "linux-mm@kvack.org" Subject: Re: [PATCH v2 3/3] mm/slub: Use percpu partial free counter In-Reply-To: <1597061872-58724-4-git-send-email-xlpang@linux.alibaba.com> Message-ID: References: <1597061872-58724-1-git-send-email-xlpang@linux.alibaba.com> <1597061872-58724-4-git-send-email-xlpang@linux.alibaba.com> User-Agent: Alpine 2.22 (DEB 394 2020-01-19) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Stat-Signature: q8n47qxejkgd6tw3ufcj4hxyeme8u97o X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 4A3A9A0009CE Received-SPF: none (gentwo.de>: No applicable sender policy available) receiver=imf24; identity=mailfrom; envelope-from=""; helo=gentwo.de; client-ip=161.97.139.209 X-HE-DKIM-Result: none/none X-HE-Tag: 1614676494-338598 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: On Mon, 10 Aug 2020, Xunlei Pang wrote: > > diff --git a/mm/slab.h b/mm/slab.h > index c85e2fa..a709a70 100644 > --- a/mm/slab.h > +++ b/mm/slab.h > @@ -616,7 +616,7 @@ struct kmem_cache_node { > #ifdef CONFIG_SLUB > unsigned long nr_partial; > struct list_head partial; > - atomic_long_t partial_free_objs; > + atomic_long_t __percpu *partial_free_objs; A percpu counter is never atomic. Just use unsigned long and use this_cpu operations for this thing. That should cut down further on the overhead. > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -1775,11 +1775,21 @@ static void discard_slab(struct kmem_cache *s, struct page *page) > /* > * Management of partially allocated slabs. > */ > +static inline long get_partial_free(struct kmem_cache_node *n) > +{ > + long nr = 0; > + int cpu; > + > + for_each_possible_cpu(cpu) > + nr += atomic_long_read(per_cpu_ptr(n->partial_free_objs, cpu)); this_cpu_read(*n->partial_free_objs) > static inline void > __update_partial_free(struct kmem_cache_node *n, long delta) > { > - atomic_long_add(delta, &n->partial_free_objs); > + atomic_long_add(delta, this_cpu_ptr(n->partial_free_objs)); this_cpu_add() and so on.