Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756163Ab2FFOlt (ORCPT ); Wed, 6 Jun 2012 10:41:49 -0400 Received: from e34.co.us.ibm.com ([32.97.110.152]:41030 "EHLO e34.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753709Ab2FFOlr (ORCPT ); Wed, 6 Jun 2012 10:41:47 -0400 Date: Wed, 6 Jun 2012 07:41:28 -0700 From: "Paul E. McKenney" To: Peter Zijlstra Cc: Thomas Gleixner , "Luck, Tony" , "Yu, Fenghua" , Rusty Russell , Ingo Molnar , H Peter Anvin , "Siddha, Suresh B" , "Mallick, Asit K" , Arjan Dan De Ven , linux-kernel , x86 , linux-pm , "Srivatsa S. Bhat" Subject: Re: [PATCH 0/6] x86/cpu hotplug: Wake up offline CPU via mwait or nmi Message-ID: <20120606144127.GF19601@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <3E5A0FA7E9CA944F9D5414FEC6C7122007728081@ORSMSX105.amr.corp.intel.com> <1338913190.2749.10.camel@twins> <3908561D78D1C84285E8C5FCA982C28F19300965@ORSMSX104.amr.corp.intel.com> <1338918625.2749.29.camel@twins> <1338925756.2749.36.camel@twins> <1338931856.2749.57.camel@twins> <20120605221240.GW2388@linux.vnet.ibm.com> <1338972223.2749.79.camel@twins> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1338972223.2749.79.camel@twins> User-Agent: Mutt/1.5.21 (2010-09-15) X-Content-Scanned: Fidelis XPS MAILER x-cbid: 12060614-1780-0000-0000-00000634DA54 X-IBM-ISS-SpamDetectors: X-IBM-ISS-DetailInfo: BY=3.00000281; HX=3.00000190; KW=3.00000007; PH=3.00000001; SC=3.00000002; SDB=6.00145705; UDB=6.00033380; UTC=2012-06-06 14:41:46 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1232 Lines: 26 On Wed, Jun 06, 2012 at 10:43:43AM +0200, Peter Zijlstra wrote: > On Tue, 2012-06-05 at 15:12 -0700, Paul E. McKenney wrote: > > > What I can't see is the isolated functional, aside from the above > > > mentioned things, that's not strictly a per-cpu property, we can have a > > > group that's isolated from the rest but not from each other. > > > > I suspect that Thomas is thinking that the CPU is so idle that it no > > longer has to participate in TLB invalidation or RCU. (Thomas will > > correct me if I am confused.) But Peter, is that the level of idle > > you are thinking of? > > No, we're talking about isolated, so its very much running something. >From what I can see, if the CPU is running something, this is Thomas's "Isolated functional" state rather than his "Isolated idle" state. The isolated-idle state should not need to participate in TLB invalidation or RCU, so that the CPU never ever needs to wake up while in the isolated-idle state. Thanx, Paul -- 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/