From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751962AbaBZCcc (ORCPT ); Tue, 25 Feb 2014 21:32:32 -0500 Received: from e28smtp02.in.ibm.com ([122.248.162.2]:37758 "EHLO e28smtp02.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751202AbaBZCcb (ORCPT ); Tue, 25 Feb 2014 21:32:31 -0500 Message-ID: <530D5236.8090007@linux.vnet.ibm.com> Date: Wed, 26 Feb 2014 10:32:22 +0800 From: Michael wang User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.2.0 MIME-Version: 1.0 To: Peter Zijlstra CC: Sasha Levin , Ingo Molnar , LKML Subject: Re: sched: hang in migrate_swap References: <5305856F.3000109@linux.vnet.ibm.com> <53078241.3060201@oracle.com> <53080122.609@linux.vnet.ibm.com> <530ABB44.5000601@oracle.com> <530AD653.3000808@linux.vnet.ibm.com> <20140224071028.GW9987@twins.programming.kicks-ass.net> <530B1B80.4000307@linux.vnet.ibm.com> <20140224121218.GR15586@twins.programming.kicks-ass.net> <20140224131025.GG3104@twins.programming.kicks-ass.net> <530C2045.1090704@linux.vnet.ibm.com> <20140225104924.GK9987@twins.programming.kicks-ass.net> In-Reply-To: <20140225104924.GK9987@twins.programming.kicks-ass.net> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 14022602-5816-0000-0000-00000C808159 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/25/2014 06:49 PM, Peter Zijlstra wrote: > On Tue, Feb 25, 2014 at 12:47:01PM +0800, Michael wang wrote: >> On 02/24/2014 09:10 PM, Peter Zijlstra wrote: >>> On Mon, Feb 24, 2014 at 01:12:18PM +0100, Peter Zijlstra wrote: >>>> + if (p) { >>>> + if (unlikely(p == RETRY_TASK)) >>>> + goto again; >>> >>> We could even make that: unlikely(p & 1), I think most CPUs can encode >>> that far better than the full pointer immediate. >> >> Agree, unless odd-align stuff appeared... > > That shouldn't happen; we rely on u32 alignment all over the place. So > for general objects we should have at least the lower two bits free to > play with. Make sense :) Regards, Michael Wang > -- > 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/ >