Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966366AbWKNV2P (ORCPT ); Tue, 14 Nov 2006 16:28:15 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S966367AbWKNV2P (ORCPT ); Tue, 14 Nov 2006 16:28:15 -0500 Received: from omx2-ext.sgi.com ([192.48.171.19]:58534 "EHLO omx2.sgi.com") by vger.kernel.org with ESMTP id S966366AbWKNV2O (ORCPT ); Tue, 14 Nov 2006 16:28:14 -0500 Date: Tue, 14 Nov 2006 13:28:04 -0800 (PST) From: Christoph Lameter To: Suleiman Souhlal cc: Andi Kleen , Linux Kernel ML , vojtech@suse.cz, Jiri Bohac Subject: Re: [PATCH 0/2] Make the TSC safe to be used by gettimeofday(). In-Reply-To: <45592497.1080109@FreeBSD.org> Message-ID: References: <455916A5.2030402@FreeBSD.org> <200611140250.57160.ak@suse.de> <45592497.1080109@FreeBSD.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 740 Lines: 15 On Mon, 13 Nov 2006, Suleiman Souhlal wrote: > I believe that the results returned will always be monotonic, as long as the > frequency of the TSC does not change from under us (that is, without the > kernel knowing). This is because we "synchronize" each CPU's vxtime with a > global time source (HPET) every time we know the TSC rate changes. TSC frequencies of different clocks coming with multiple processors may vary which creates a differential even if they are initially synchronized. - 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/