Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161174AbVIPRPU (ORCPT ); Fri, 16 Sep 2005 13:15:20 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1161181AbVIPRPU (ORCPT ); Fri, 16 Sep 2005 13:15:20 -0400 Received: from [139.30.44.2] ([139.30.44.2]:12864 "EHLO gans.physik3.uni-rostock.de") by vger.kernel.org with ESMTP id S1161174AbVIPRPT (ORCPT ); Fri, 16 Sep 2005 13:15:19 -0400 Date: Fri, 16 Sep 2005 19:15:17 +0200 (CEST) From: Tim Schmielau To: Tim Bird cc: jesper.juhl@gmail.com, "Randy.Dunlap" , linux-kernel@vger.kernel.org Subject: Re: early printk timings way off In-Reply-To: <432AFB01.3050809@am.sony.com> Message-ID: References: <9a87484905091515495f435db7@mail.gmail.com> <432AFB01.3050809@am.sony.com> 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: 1001 Lines: 30 On Fri, 16 Sep 2005, Tim Bird wrote: > UPDATE: > [Based on Tim Schmielau's analysis, maybe it's not the raw TSC > value, but an unititialized jiffy value coming back from sched_clock(). > In this case, the value is worthless until after time_init(). Well, it's not uninitialized, but initialized to a very high value. So the differences between the large values still contain useful information. > This may be why you're seeing a jump in the first "real" value > returned. Yep. > Previously on x86, the pre-time_init() value was useful (wrong as an absolute > number, but right in relatives values.) This should still be the case. So, one jump (probably the first) happens when time_init sets use_tsc. Do we understand the other jump as well? Tim - 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/