From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f43.google.com (mail-wm0-f43.google.com [74.125.82.43]) by kanga.kvack.org (Postfix) with ESMTP id B64936B0253 for ; Wed, 30 Mar 2016 06:38:46 -0400 (EDT) Received: by mail-wm0-f43.google.com with SMTP id 20so64452730wmh.1 for ; Wed, 30 Mar 2016 03:38:46 -0700 (PDT) Received: from outbound-smtp10.blacknight.com (outbound-smtp10.blacknight.com. [46.22.139.15]) by mx.google.com with ESMTPS id uq5si4297594wjc.43.2016.03.30.03.38.45 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 30 Mar 2016 03:38:45 -0700 (PDT) Received: from mail.blacknight.com (pemlinmail01.blacknight.ie [81.17.254.10]) by outbound-smtp10.blacknight.com (Postfix) with ESMTPS id 34EB01C186E for ; Wed, 30 Mar 2016 11:38:45 +0100 (IST) Date: Wed, 30 Mar 2016 11:38:39 +0100 From: Mel Gorman Subject: Re: [PATCH] Revert "mm/page_alloc: protect pcp->batch accesses with ACCESS_ONCE" Message-ID: <20160330103839.GA4773@techsingularity.net> References: <1459333327-89720-1-git-send-email-hekuang@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <1459333327-89720-1-git-send-email-hekuang@huawei.com> Sender: owner-linux-mm@kvack.org List-ID: To: He Kuang Cc: akpm@linux-foundation.org, mhocko@suse.com, vbabka@suse.cz, rientjes@google.com, cody@linux.vnet.ibm.com, gilad@benyossef.com, kosaki.motohiro@gmail.com, mgorman@suse.de, penberg@kernel.org, lizefan@huawei.com, wangnan0@huawei.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org On Wed, Mar 30, 2016 at 10:22:07AM +0000, He Kuang wrote: > This reverts commit 998d39cb236fe464af86a3492a24d2f67ee1efc2. > > When local irq is disabled, a percpu variable does not change, so we can > remove the access macros and let the compiler optimize the code safely. > batch can be changed from other contexts. Why is this safe? -- Mel Gorman SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org