From patchwork Tue Oct 13 23:48:40 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Morton X-Patchwork-Id: 11836251 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 74293921 for ; Tue, 13 Oct 2020 23:48:44 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 37E8821D7A for ; Tue, 13 Oct 2020 23:48:44 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="ScSdMgNv" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 37E8821D7A Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 48A6C6B0068; Tue, 13 Oct 2020 19:48:43 -0400 (EDT) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id 43ABF900002; Tue, 13 Oct 2020 19:48:43 -0400 (EDT) X-Original-To: int-list-linux-mm@kvack.org X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 377796B0088; Tue, 13 Oct 2020 19:48:43 -0400 (EDT) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0027.hostedemail.com [216.40.44.27]) by kanga.kvack.org (Postfix) with ESMTP id 0B93B6B0087 for ; Tue, 13 Oct 2020 19:48:43 -0400 (EDT) Received: from smtpin14.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 9B7DA180AD806 for ; Tue, 13 Oct 2020 23:48:42 +0000 (UTC) X-FDA: 77368544484.14.scene33_4412bf727207 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin14.hostedemail.com (Postfix) with ESMTP id 7E6C71822987B for ; Tue, 13 Oct 2020 23:48:42 +0000 (UTC) X-Spam-Summary: 1,0,0,620709dbfdb6277f,d41d8cd98f00b204,akpm@linux-foundation.org,,RULES_HIT:41:69:355:379:800:960:965:966:967:973:988:989:1260:1263:1345:1359:1381:1431:1437:1534:1541:1711:1730:1747:1777:1792:2196:2199:2393:2525:2559:2563:2682:2685:2693:2859:2902:2916:2933:2937:2939:2942:2945:2947:2951:2954:3022:3138:3139:3140:3141:3142:3353:3865:3866:3867:3868:3870:3871:3872:3874:3934:3936:3938:3941:3944:3947:3950:3953:3956:3959:4321:4385:4390:4395:5007:6119:6261:6653:6737:7576:7903:8599:9010:9025:9545:10004:10913:11026:11473:11658:11914:12043:12048:12296:12297:12517:12519:12555:12679:12783:12986:13069:13161:13229:13311:13357:13846:14096:14181:14384:14721:14849:21080:21451:21627:21939:21990:30054,0,RBL:198.145.29.99:@linux-foundation.org:.lbl8.mailshell.net-62.2.0.100 64.100.201.201;04y8ne8cnge4ncxfpuc77xu8hzgm8opqxz9p9fbzfs1raepwxazb3wphqkjogxt.mahdydc5ph34yhyxm5yx45cmzgdwt5ew4zty6u6ndrxjdmspee8ktaik9zixgxo.h-lbl8.mailshell.net-223.238.255.100,CacheIP:none,Bayesian:0.5,0.5, 0.5,Netc X-HE-Tag: scene33_4412bf727207 X-Filterd-Recvd-Size: 3368 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf37.hostedemail.com (Postfix) with ESMTP for ; Tue, 13 Oct 2020 23:48:42 +0000 (UTC) Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id DD10F21582; Tue, 13 Oct 2020 23:48:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1602632921; bh=8/PBWQgz3SSTYl6EQciCTEV/iX++FB+zToIPRNXfJj4=; h=Date:From:To:Subject:In-Reply-To:From; b=ScSdMgNvvSGYQINmsduZUSwXq2LiCM1DxiVUR+1Sbkrvjm+DRQ1GK3QTC6peL+I/9 5O+tfOTkJ2Pl6SErZtwU6a3c1IVjS3Qi/hkJGiEUVYFvpvdaxJ9lAO6CYC/VeukqGa URai/M8vAvnSs52zcfsvLorQMTB56tvO0aqoD8Xo= Date: Tue, 13 Oct 2020 16:48:40 -0700 From: Andrew Morton To: akpm@linux-foundation.org, cl@linux.com, hewenliang4@huawei.com, hushiyuan@huawei.com, iamjoonsoo.kim@lge.com, linux-mm@kvack.org, mm-commits@vger.kernel.org, penberg@kernel.org, rientjes@google.com, torvalds@linux-foundation.org, wuyun.wu@huawei.com Subject: [patch 021/181] mm/slub.c: branch optimization in free slowpath Message-ID: <20201013234840.43ZfRzqi3%akpm@linux-foundation.org> In-Reply-To: <20201013164658.3bfd96cc224d8923e66a9f4e@linux-foundation.org> User-Agent: s-nail v14.8.16 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: From: Abel Wu Subject: mm/slub.c: branch optimization in free slowpath The two conditions are mutually exclusive and gcc compiler will optimise this into if-else-like pattern. Given that the majority of free_slowpath is free_frozen, let's provide some hint to the compilers. Tests (perf bench sched messaging -g 20 -l 400000, executed 10x after reboot) are done and the summarized result: un-patched patched max. 192.316 189.851 min. 187.267 186.252 avg. 189.154 188.086 stdev. 1.37 0.99 Link: http://lkml.kernel.org/r/20200813101812.1617-1-wuyun.wu@huawei.com Signed-off-by: Abel Wu Acked-by: Christoph Lameter Cc: Pekka Enberg Cc: David Rientjes Cc: Joonsoo Kim Cc: Hewenliang Cc: Hu Shiyuan Signed-off-by: Andrew Morton --- mm/slub.c | 23 ++++++++++++----------- 1 file changed, 12 insertions(+), 11 deletions(-) --- a/mm/slub.c~mm-slub-branch-optimization-in-free-slowpath +++ a/mm/slub.c @@ -3019,20 +3019,21 @@ static void __slab_free(struct kmem_cach if (likely(!n)) { - /* - * If we just froze the page then put it onto the - * per cpu partial list. - */ - if (new.frozen && !was_frozen) { + if (likely(was_frozen)) { + /* + * The list lock was not taken therefore no list + * activity can be necessary. + */ + stat(s, FREE_FROZEN); + } else if (new.frozen) { + /* + * If we just froze the page then put it onto the + * per cpu partial list. + */ put_cpu_partial(s, page, 1); stat(s, CPU_PARTIAL_FREE); } - /* - * The list lock was not taken therefore no list - * activity can be necessary. - */ - if (was_frozen) - stat(s, FREE_FROZEN); + return; }