From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754530Ab0AMCWU (ORCPT ); Tue, 12 Jan 2010 21:22:20 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751644Ab0AMCWU (ORCPT ); Tue, 12 Jan 2010 21:22:20 -0500 Received: from mga11.intel.com ([192.55.52.93]:36774 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751221Ab0AMCWT (ORCPT ); Tue, 12 Jan 2010 21:22:19 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.49,264,1262592000"; d="scan'208";a="530755140" Subject: Re: [PATCH -v2 5/5] x86: use dmi check to treat disabled cpus as hotplug cpus. From: Suresh Siddha Reply-To: Suresh Siddha To: Yinghai Lu Cc: Linus Torvalds , "ananth@in.ibm.com" , Ingo Molnar , Thomas Gleixner , "H. Peter Anvin" , Andrew Morton , "linux-kernel@vger.kernel.org" In-Reply-To: <4B4D2C44.2060709@kernel.org> References: <1263338274-6485-1-git-send-email-yinghai@kernel.org> <1263338274-6485-5-git-send-email-yinghai@kernel.org> <1263340563.2854.1011.camel@sbs-t61.sc.intel.com> <4B4D0E39.10200@kernel.org> <1263347315.2854.1296.camel@sbs-t61.sc.intel.com> <4B4D2811.7000001@kernel.org> <1263348363.2854.1360.camel@sbs-t61.sc.intel.com> <4B4D2C44.2060709@kernel.org> Content-Type: text/plain Organization: Intel Corp Date: Tue, 12 Jan 2010 18:21:08 -0800 Message-Id: <1263349268.2854.1386.camel@sbs-t61.sc.intel.com> Mime-Version: 1.0 X-Mailer: Evolution 2.26.3 (2.26.3-1.fc11) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2010-01-12 at 18:13 -0800, Yinghai Lu wrote: > On 01/12/2010 06:06 PM, Suresh Siddha wrote: > > On Tue, 2010-01-12 at 17:55 -0800, Yinghai Lu wrote: > >> you mean this blacklist could be too long? > > > > yes. > > > >> > >> switch to whitelist for the box can treat disabled cpus as hotplug > >> cpus? > > > > Do we really need all this? Systems which support physical hotplug > > typically have lot's of cpu's (mostly will have atleast > 8). Even if we > > really need to identify, then perhaps we can check if ACPI has any hints > > regarding the physical hotplug support at boot time (we should check > > with Andi Kleen or Len Brown on this). > > > > For now, I think we can keep it simple by using the detected enabled > > cpu's. > > sth like this ? Well, I was referring more to the apic model selection than the prefill case. About this possible cpu's, will the wastage be more than few kb for few disabled cpu's. thanks, suresh > --- > arch/x86/kernel/smpboot.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > Index: linux-2.6/arch/x86/kernel/smpboot.c > =================================================================== > --- linux-2.6.orig/arch/x86/kernel/smpboot.c > +++ linux-2.6/arch/x86/kernel/smpboot.c > @@ -1190,7 +1190,6 @@ early_param("possible_cpus", _setup_poss > * - Ashok Raj > * > * Three ways to find out the number of additional hotplug CPUs: > - * - If the BIOS specified disabled CPUs in ACPI/mptables use that. > * - The user can overwrite it with possible_cpus=NUM > * - Otherwise don't reserve additional CPUs. > * We do this because additional CPUs waste a lot of memory. > @@ -1205,7 +1204,7 @@ __init void prefill_possible_map(void) > num_processors = 1; > > if (setup_possible_cpus == -1) > - possible = num_processors + disabled_cpus; > + possible = num_processors; > else > possible = setup_possible_cpus; >