Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756010AbXHHERR (ORCPT ); Wed, 8 Aug 2007 00:17:17 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750830AbXHHERE (ORCPT ); Wed, 8 Aug 2007 00:17:04 -0400 Received: from pentafluge.infradead.org ([213.146.154.40]:57626 "EHLO pentafluge.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750768AbXHHERB (ORCPT ); Wed, 8 Aug 2007 00:17:01 -0400 Subject: Re: [PATCH] msleep() with hrtimers From: Arjan van de Ven To: Roman Zippel Cc: Jonathan Corbet , linux-kernel@vger.kernel.org, Thomas Gleixner , akpm@linux-foundation.org, Ingo Molnar In-Reply-To: References: <15327.1186166232@lwn.net> <1186170407.3153.8.camel@laptopd505.fenrus.org> <1186185229.3153.11.camel@laptopd505.fenrus.org> <1186255149.2777.3.camel@laptopd505.fenrus.org> <1186360983.2697.8.camel@laptopd505.fenrus.org> <1186378798.2697.10.camel@laptopd505.fenrus.org> <1186415621.2706.4.camel@laptopd505.fenrus.org> Content-Type: text/plain Organization: Intel International BV Date: Tue, 07 Aug 2007 21:15:12 -0700 Message-Id: <1186546512.2862.3.camel@laptopd505.fenrus.org> Mime-Version: 1.0 X-Mailer: Evolution 2.10.3 (2.10.3-2.fc7) Content-Transfer-Encoding: 7bit X-SRS-Rewrite: SMTP reverse-path rewritten from by pentafluge.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1487 Lines: 35 On Tue, 2007-08-07 at 14:45 +0200, Roman Zippel wrote: > Hi, > > On Mon, 6 Aug 2007, Arjan van de Ven wrote: > > > So, let me ask a direct question: What do you think is specifically > > wrong about changing the msleep() implementation as is done here? The > > behavior is clearly an improvement, so what is your objection on the > > flipside? > > Again, we have two different timer APIs for a reason yes because we have different usage patterns for timers. (exact/course or expiring/not-typically-expiring; I know you have some other opinion here than other people). For this case it's relatively simple imo: The existing implementation has a *typical* behavior which is 100% to 2000% worse than what the user of the API asks for. And that is totally unneeded to be so crappy; it can be much more exact easily as shown by this patch. You keep claiming that hrtimers are so incredibly expensive; but for msleep()... which is mostly called during driver init ... I really don't buy that it's really expensive. We're not doing this a gazilion times per second obviously... -- if you want to mail me at work (you don't), use arjan (at) linux.intel.com Test the interaction between Linux and your BIOS via http://www.linuxfirmwarekit.org - 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/