Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964777AbVISWoI (ORCPT ); Mon, 19 Sep 2005 18:44:08 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964776AbVISWoI (ORCPT ); Mon, 19 Sep 2005 18:44:08 -0400 Received: from 213-239-205-147.clients.your-server.de ([213.239.205.147]:51669 "EHLO mail.tglx.de") by vger.kernel.org with ESMTP id S964775AbVISWoG (ORCPT ); Mon, 19 Sep 2005 18:44:06 -0400 Subject: Re: [ANNOUNCE] ktimers subsystem From: Thomas Gleixner Reply-To: tglx@linutronix.de To: Christoph Lameter Cc: linux-kernel@vger.kernel.org, mingo@elte.hu, akpm@osdl.org, george@mvista.com, johnstul@us.ibm.com, paulmck@us.ibm.com In-Reply-To: References: <20050919184834.1.patchmail@tglx.tec.linutronix.de> <1127168232.24044.265.camel@tglx.tec.linutronix.de> Content-Type: text/plain Organization: linutronix Date: Tue, 20 Sep 2005 00:44:09 +0200 Message-Id: <1127169849.24044.279.camel@tglx.tec.linutronix.de> Mime-Version: 1.0 X-Mailer: Evolution 2.2.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1494 Lines: 37 On Mon, 2005-09-19 at 15:24 -0700, Christoph Lameter wrote: > > We should rather ask glibc people why gettimeofday() / clock_getttime() > > is called inside the library code all over the place for non obvious > > reasons. > > You can ask lots of application vendors the same question because its all > over lots of user space code. The fact is that gettimeofday() / > clock_gettime() efficiency is very critical to the performance of many > applications on Linux. That is why the addtion of one add instruction may > better be carefully considered. Hmm. I don't understand the argument line completely. 1. The kernel has to provide ugly mechanisms because a lot of applications implementations are doing the Wrong Thing ? 2. All gettimeofday implementations I have looked at do a lot of math anyway, so its definitely more interesting to look at those oddities rather than discussing a single add. John Stulz timeofday rework have a clean solution for this - please do not argue about the div64 in his original patches which he is reworking at the moment. > Many platforms can execute gettimeofday > without having to enter the kernel. Which ones ? How is this achieved with respect to all the time adjust, correction... code ? tglx - 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/