From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756493Ab2GFUJZ (ORCPT ); Fri, 6 Jul 2012 16:09:25 -0400 Received: from g1t0026.austin.hp.com ([15.216.28.33]:12647 "EHLO g1t0026.austin.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751052Ab2GFUJX (ORCPT ); Fri, 6 Jul 2012 16:09:23 -0400 Message-ID: <4FF745F1.9030103@hp.com> Date: Fri, 06 Jul 2012 14:09:21 -0600 From: Khalid Aziz User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:13.0) Gecko/20120615 Thunderbird/13.0.1 MIME-Version: 1.0 To: Toshi Kani CC: Jiang Liu , lenb@kernel.org, linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] ACPI: Add ACPI CPU hot-remove support References: <1340981479-6521-1-git-send-email-toshi.kani@hp.com> <4FF711DE.1030108@gmail.com> <1341602020.16730.695.camel@misato.fc.hp.com> In-Reply-To: <1341602020.16730.695.camel@misato.fc.hp.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/06/2012 01:13 PM, Toshi Kani wrote: > > For step 2) and 4), I am wondering if they are relevant to CPU hotplug > these days. In ACPI namespace, a processor object represents a logical > processor (or a core when hyper-threading is disabled). A physical > processor (i.e. a socket) usually has multiple cores, and memory > controller and bus interface are part of the socket functionality. > Hence, I think step 2) and 4) belong to socket-level hot-removal > operation, which can be implemented as container hot-remove when a > socket is represented with a container object. What does it mean to eject just a core in that case? If there are seven other cores in the physical processor and you get a request to eject one core, what would you expect kernel to do - simply move all processes and interrupts off of that core, take it out of scheduling consideration and simply idle the core? If yes, how is that any different from simply offlining a core? If you are ejecting individual cores at a time, do you keep track of how many you have ejected and then eject the entire physical CPU along with memory and IOH associated with the socket when the last core is ejected? -- Khalid ==================================================================== Khalid Aziz Unix Systems Lab (970)898-9214 Hewlett-Packard khalid.aziz@hp.com Fort Collins, CO