From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754926AbXHAQMW (ORCPT ); Wed, 1 Aug 2007 12:12:22 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751336AbXHAQMF (ORCPT ); Wed, 1 Aug 2007 12:12:05 -0400 Received: from one.firstfloor.org ([213.235.205.2]:47534 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751396AbXHAQMD (ORCPT ); Wed, 1 Aug 2007 12:12:03 -0400 Date: Wed, 1 Aug 2007 18:11:59 +0200 From: Andi Kleen To: Ingo Molnar Cc: Roman Zippel , Andi Kleen , Mike Galbraith , Linus Torvalds , Andrew Morton , linux-kernel@vger.kernel.org Subject: Re: CFS review Message-ID: <20070801161159.GA19776@one.firstfloor.org> References: <20070711214649.GK14435@v2.random> <1184302024.6709.11.camel@Homer.simpson.net> <1184389456.6632.13.camel@Homer.simpson.net> <20070801143624.GA18043@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070801143624.GA18043@elte.hu> User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Aug 01, 2007 at 04:36:24PM +0200, Ingo Molnar wrote: > > * Roman Zippel wrote: > > > > jiffies based sched_clock should be soon very rare. It's probably > > > not worth optimizing for it. > > > > I'm not so sure about that. sched_clock() has to be fast, so many > > archs may want to continue to use jiffies. [...] > > i think Andi was talking about the vast majority of the systems out > there. For example, check out the arch demography of current Fedora > installs (according to the Smolt opt-in UUID based user metrics): I meant that in many cases where the TSC is considered unreliable today it'll be possible to use it anyways at least for sched_clock() (and possibly even gtod()) The exception would be system which really have none, but there should be very few of those. -Andi