From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1764986AbXHANdk (ORCPT ); Wed, 1 Aug 2007 09:33:40 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1762522AbXHANdb (ORCPT ); Wed, 1 Aug 2007 09:33:31 -0400 Received: from scrub.xs4all.nl ([194.109.195.176]:4476 "EHLO scrub.xs4all.nl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1762532AbXHANd2 (ORCPT ); Wed, 1 Aug 2007 09:33:28 -0400 Date: Wed, 1 Aug 2007 15:33:17 +0200 (CEST) From: Roman Zippel X-X-Sender: roman@scrub.home To: Andi Kleen cc: Mike Galbraith , Linus Torvalds , Ingo Molnar , Andrew Morton , linux-kernel@vger.kernel.org Subject: Re: CFS review In-Reply-To: Message-ID: References: <20070710013152.ef2cd200.akpm@linux-foundation.org> <20070711174252.GA16793@elte.hu> <20070711211638.GE18767@one.firstfloor.org> <20070711214649.GK14435@v2.random> <1184302024.6709.11.camel@Homer.simpson.net> <1184389456.6632.13.camel@Homer.simpson.net> 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 Hi, On Wed, 1 Aug 2007, Andi Kleen wrote: > > especially if one already knows that > > scheduler clock has only limited resolution (because it's based on > > jiffies), it becomes possible to use mostly 32bit values. > > 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. As soon as one does that one can also save a lot of computational overhead by using 32bit instead of 64bit. The question is then how easy that is possible. bye, Roman