Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932361AbXIISRi (ORCPT ); Sun, 9 Sep 2007 14:17:38 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932119AbXIISRa (ORCPT ); Sun, 9 Sep 2007 14:17:30 -0400 Received: from sovereign.computergmbh.de ([85.214.69.204]:43384 "EHLO sovereign.computergmbh.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932105AbXIISRa (ORCPT ); Sun, 9 Sep 2007 14:17:30 -0400 Date: Sun, 9 Sep 2007 20:17:28 +0200 (CEST) From: Jan Engelhardt To: Arjan van de Ven cc: Dennis Lubert , linux-kernel@vger.kernel.org Subject: Re: tsc timer related problems/questions In-Reply-To: <20070909174935.7c00bbb7@laptopd505.fenrus.org> Message-ID: References: <1189355506.6255.60.camel@speedy.projectiwear.org> <20070909174935.7c00bbb7@laptopd505.fenrus.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: 815 Lines: 23 On Sep 9 2007 17:49, Arjan van de Ven wrote: >> >> Question: Why are only Intel CPUs considered as stable? Could there be >> implemented a more sophisticated heuristic, that actually does some >> tests for tsc stability? > >on AMD multi-socket systems, afaik the tsc is not synchronized between >packages. On Intel the tsc is derived from the FSB which is shared >between the packages. Also, the TSC is not necessarily constant wrt. CPU clock speed. If your program stalls, the core may reduce frequency and hence TSC values are not linear to time anymore. Jan -- - 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/