Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965122AbWECHIq (ORCPT ); Wed, 3 May 2006 03:08:46 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965124AbWECHIq (ORCPT ); Wed, 3 May 2006 03:08:46 -0400 Received: from mail.gmx.de ([213.165.64.20]:48596 "HELO mail.gmx.net") by vger.kernel.org with SMTP id S965123AbWECHIp (ORCPT ); Wed, 3 May 2006 03:08:45 -0400 X-Authenticated: #14349625 Subject: Re: sched_clock() uses are broken From: Mike Galbraith To: Nick Piggin Cc: Andi Kleen , Christopher Friesen , Russell King , linux-kernel@vger.kernel.org In-Reply-To: <445791D3.9060306@yahoo.com.au> References: <20060502132953.GA30146@flint.arm.linux.org.uk> <44578EB9.8050402@nortel.com> <200605021859.18948.ak@suse.de> <445791D3.9060306@yahoo.com.au> Content-Type: text/plain Date: Wed, 03 May 2006 09:09:15 +0200 Message-Id: <1146640155.7526.27.camel@homer> Mime-Version: 1.0 X-Mailer: Evolution 2.4.0 Content-Transfer-Encoding: 7bit X-Y-GMX-Trusted: 0 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 835 Lines: 19 On Wed, 2006-05-03 at 03:07 +1000, Nick Piggin wrote: > Other problem is that some people didn't RTFM and have started trying to > use it for precise accounting :( Are you talking about me perchance? I don't really care about precision _that_ much, though I certainly do want to tighten timeslice accounting. Given that most people are going to end up using the pm_timer anyway, I don't see the point of even having a sched_clock(). If it's jiffy resolution, it's useless. If it's wildly inaccurate (as it is in the SMP case, monotonicity issues aside) it's more than useless. -Mike - 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/