Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932273AbVJTPzS (ORCPT ); Thu, 20 Oct 2005 11:55:18 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932314AbVJTPzS (ORCPT ); Thu, 20 Oct 2005 11:55:18 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:31457 "EHLO mx2.mail.elte.hu") by vger.kernel.org with ESMTP id S932273AbVJTPzQ (ORCPT ); Thu, 20 Oct 2005 11:55:16 -0400 Date: Thu, 20 Oct 2005 17:55:25 +0200 From: Ingo Molnar To: Steven Rostedt Cc: john stultz , tglx@linutronix.de, linux-kernel@vger.kernel.org Subject: Re: Ktimer / -rt9 (+custom) monotonic_clock going backwards. Message-ID: <20051020155525.GA10360@elte.hu> References: <1129747172.27168.149.camel@cog.beaverton.ibm.com> <20051020073416.GA28581@elte.hu> <20051020080107.GA31342@elte.hu> <20051020085955.GB2903@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.2.1i X-ELTE-SpamScore: 0.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=0.0 required=5.9 tests=AWL autolearn=disabled SpamAssassin version=3.0.4 0.0 AWL AWL: From: address is in the auto white-list X-ELTE-VirusStatus: clean Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 907 Lines: 25 * Steven Rostedt wrote: > > I just switched cycle_t to u64 and hackbench no longer makes the time go > > backwards. > > > > John, would this cause any problems to keep cycle_t at s64? > > I mean at u64. ugh. There's both cycles_t and cycle_t. We should unify the two and it should be 64-bit. The faster systems get, the sooner the 32-bit counter overflows. 64-bit systems are keeping 32-bit compatibility for quite some time to come. So with an 8GHz CPU the 32-bit cycle_t would wrap in like 500 msecs, way too fast to rely on ... (even with a 4GHz CPUs it's only one second.) i've made cycle_t u64 and have uploaded -rt14. Ingo - 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/