From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932998Ab1IBBSF (ORCPT ); Thu, 1 Sep 2011 21:18:05 -0400 Received: from mga11.intel.com ([192.55.52.93]:30662 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932809Ab1IBBSB (ORCPT ); Thu, 1 Sep 2011 21:18:01 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.68,316,1312182000"; d="scan'208";a="47874164" Message-ID: <4E602EC8.9010306@intel.com> Date: Fri, 02 Sep 2011 09:18:00 +0800 From: Huang Ying User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.20) Gecko/20110820 Iceowl/1.0b2 Icedove/3.1.12 MIME-Version: 1.0 To: Peter Zijlstra CC: Andrew Morton , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH -mm 1/2] irq_work, Use llist in irq_work References: <1314681384-20881-1-git-send-email-ying.huang@intel.com> <1314681384-20881-2-git-send-email-ying.huang@intel.com> <1314785405.23993.21.camel@twins> <4E5EE409.3060102@intel.com> <1314863829.7945.9.camel@twins> <4E5F45F6.70009@intel.com> <1314871201.7945.17.camel@twins> In-Reply-To: <1314871201.7945.17.camel@twins> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/01/2011 06:00 PM, Peter Zijlstra wrote: > On Thu, 2011-09-01 at 16:44 +0800, Huang Ying wrote: > >> Because llist is in library, it may be used in highly contended case and >> light/un-contended loads. So maybe code as above is best choice for llist. > > Well the thing is, if you're heavily contended you should probably be > doing something else.. So which solution is preferable? 1) no cpu_relax 2) cpu_relax after first cmpxchg Personally, I prefer 2). It should have acceptable overhead in ligh/un-contended loads. Do you agree. Best Regards, Huang Ying