Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757396AbYJVUK2 (ORCPT ); Wed, 22 Oct 2008 16:10:28 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753685AbYJVUKS (ORCPT ); Wed, 22 Oct 2008 16:10:18 -0400 Received: from one.firstfloor.org ([213.235.205.2]:42626 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754197AbYJVUKR (ORCPT ); Wed, 22 Oct 2008 16:10:17 -0400 Date: Wed, 22 Oct 2008 22:17:43 +0200 From: Andi Kleen To: Ingo Molnar Cc: Alok Kataria , Andi Kleen , "H. Peter Anvin" , LKML , the arch/x86 maintainers , Daniel Hecht Subject: Re: [PATCH] Skip tsc synchronization checks if CONSTANT_TSC bit is set. Message-ID: <20081022201743.GR12825@one.firstfloor.org> References: <1224552902.2640.88.camel@alok-dev1> <874p36fflp.fsf@basil.nowhere.org> <1224607284.6161.22.camel@alok-dev1> <20081021174008.GH12825@one.firstfloor.org> <1224612294.6161.43.camel@alok-dev1> <20081021181536.GI12825@one.firstfloor.org> <1224616236.6161.60.camel@alok-dev1> <20081021192746.GJ12825@one.firstfloor.org> <1224703427.13953.8.camel@alok-dev1> <20081022192622.GA30930@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20081022192622.GA30930@elte.hu> User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 544 Lines: 13 > the sync check is there to check the _offset_ between CPUs. CONSTANT_TSC > is not a guarantee that the TSC will be coherent across all CPUs. I cannot find a quote for it in the docs now, but iirc the AMD definition of the bit guarantees offset, aka full synchronization over the system. -Andi -- 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/