Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753763Ab2FSAFZ (ORCPT ); Mon, 18 Jun 2012 20:05:25 -0400 Received: from fgwmail6.fujitsu.co.jp ([192.51.44.36]:40128 "EHLO fgwmail6.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752946Ab2FSAFY (ORCPT ); Mon, 18 Jun 2012 20:05:24 -0400 X-SecurityPolicyCheck: OK by SHieldMailChecker v1.7.4 Message-ID: <4FDFC179.3050203@jp.fujitsu.com> Date: Tue, 19 Jun 2012 09:02:01 +0900 From: Kamezawa Hiroyuki User-Agent: Mozilla/5.0 (Windows NT 6.0; rv:12.0) Gecko/20120428 Thunderbird/12.0.1 MIME-Version: 1.0 To: Wanpeng Li CC: Glauber Costa , Johannes Weiner , Michal Hocko , Balbir Singh , cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Gavin Shan Subject: Re: [PATCH] mm/memcg: add unlikely to mercg->move_charge_at_immigrate References: <1340025022-7272-1-git-send-email-liwp.linux@gmail.com> <4FDF2890.3020004@parallels.com> <20120618131918.GA2600@kernel> In-Reply-To: <20120618131918.GA2600@kernel> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1119 Lines: 32 (2012/06/18 22:19), Wanpeng Li wrote: > On Mon, Jun 18, 2012 at 05:09:36PM +0400, Glauber Costa wrote: >> On 06/18/2012 05:10 PM, Wanpeng Li wrote: >>> From: Wanpeng Li >>> >>> move_charge_at_immigrate feature is disabled by default. Charges >>> are moved only when you move mm->owner and it also add additional >>> overhead. >> >> How big is this overhead? >> >> That's hardly a fast path. And if it happens to matter, it will be >> just bigger when you enable it, and the compiler start giving the >> wrong hints to the code. > > Thank you for your quick response. > > Oh, Maybe I should just write comments "move_charge_at_immigrate feature > is disabled by default. So add "unlikely", in order to compiler can optimize." > This doesn't affect the performance. likely/unlikely which doesn't affect performance is never welcomed. Thanks, -Kame -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/