Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759954AbYBZDj7 (ORCPT ); Mon, 25 Feb 2008 22:39:59 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755229AbYBZDjv (ORCPT ); Mon, 25 Feb 2008 22:39:51 -0500 Received: from server54.tchmachines.com ([72.9.244.106]:34955 "EHLO server54.tchmachines.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753843AbYBZDju (ORCPT ); Mon, 25 Feb 2008 22:39:50 -0500 Date: Mon, 25 Feb 2008 19:39:45 -0800 From: Ravikiran Thirumalai To: Yinghai Lu Cc: Andi Kleen , Ingo Molnar , Andrew Morton , Linux Kernel Mailing List , shai@scalemp.com Subject: Re: [PATCH] x86_64: make amd quad core 8 socket system not be clustered_box v2 Message-ID: <20080226033945.GJ3143@localdomain> References: <200802210258.45011.yinghai.lu@sun.com> <200802221102.31019.yinghai.lu@sun.com> <47BF1BD9.4020808@firstfloor.org> <200802232148.43255.yinghai.lu@sun.com> <20080224122903.GC13637@one.firstfloor.org> <20080225190819.GE3143@localdomain> <86802c440802251405w7025a8b2na5fde4dcbf56067e@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <86802c440802251405w7025a8b2na5fde4dcbf56067e@mail.gmail.com> User-Agent: Mutt/1.5.13 (2006-08-11) X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - server54.tchmachines.com X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - scalemp.com Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1775 Lines: 41 On Mon, Feb 25, 2008 at 02:05:45PM -0800, Yinghai Lu wrote: >On Mon, Feb 25, 2008 at 11:08 AM, Ravikiran Thirumalai > wrote: >> ... >> Andi, Yes. AMD based vSMPowered systems uses clustered APICs, and this >> check base on cpu vendor id is not good :(. > >please check if you happy with > >http://lkml.org/lkml/2008/2/24/273 > I don't quite understand the purpose of the patch to begin with. Looking at the current x86 git tree, apic_is_clustered_box is used only to determine if tsc is synchronized on the platform. The AMD docs imply that TSC's are not guaranteed to be synced across cores between nodes -- Opteron BKDG for family 10h, Section 2.9.4: Note: Timers associated with different CPU cores in the same processor increment at the same rate. Timers associated with different CPU cores in different processors increment at slightly different rates if (1) they are located on different nodes and (2) CLKIN for these nodes is derived from different, non-synchronized oscillator sources. But that is not what the x86 tree does (with your patches) -- it looks for the X86_FEATURE_CONSTANT_TSC at unsynchronized_tsc() and assumes a synchronized clock. Huh!?? Am i missing something here? X86_FEATURE_CONSTANT_TSC is set from CPUID Fn8000_0007 -- TscInvariant bit, which implies TSC is not affected by change in PM states. This does not talk about whether CLKIN for different packages are from synchronized/non synchronized oscillator sources in the above quote. Thanks, Kiran -- 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/