Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932522AbVITE5s (ORCPT ); Tue, 20 Sep 2005 00:57:48 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932538AbVITE5s (ORCPT ); Tue, 20 Sep 2005 00:57:48 -0400 Received: from zctfs063.nortelnetworks.com ([47.164.128.120]:48891 "EHLO zctfs063.nortelnetworks.com") by vger.kernel.org with ESMTP id S932522AbVITE5r (ORCPT ); Tue, 20 Sep 2005 00:57:47 -0400 Message-ID: <432F96C1.70303@nortel.com> Date: Mon, 19 Sep 2005 22:57:37 -0600 From: "Christopher Friesen" User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.6) Gecko/20040115 X-Accept-Language: en-us, en MIME-Version: 1.0 To: tglx@linutronix.de CC: Christoph Lameter , linux-kernel@vger.kernel.org, mingo@elte.hu, akpm@osdl.org, george@mvista.com, johnstul@us.ibm.com, paulmck@us.ibm.com Subject: Re: [ANNOUNCE] ktimers subsystem References: <20050919184834.1.patchmail@tglx.tec.linutronix.de> <1127168232.24044.265.camel@tglx.tec.linutronix.de> <432F3E0F.1010002@nortel.com> <1127170488.24044.291.camel@tglx.tec.linutronix.de> In-Reply-To: <1127170488.24044.291.camel@tglx.tec.linutronix.de> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 20 Sep 2005 04:57:39.0295 (UTC) FILETIME=[D35526F0:01C5BD9F] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1359 Lines: 35 Thomas Gleixner wrote: > On Mon, 2005-09-19 at 16:39 -0600, Christopher Friesen wrote: > >>Thomas Gleixner 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. >>--flight-recorder style logs > If you want to implement such stuff efficiently you rely on rdtscll() on > x86 or other monotonic easy accessible time souces and not on a > permanent call to gettimeofday. Not portable across architectures, and doesn't work across all smp/numa environments. Also not easy to compare with other nodes on the network, whereas with ntp-synch'd nodes you can use gettimeofday() for quite accurate correlations. > Please beware me of red herrings. If application developers code with > respect to random OS worst case behaviour then they should not complain > that OS N is having an additional add instruction in one of the pathes. Actually I'm not complaining about additional add instructions. I was just suggesting some reasons why apps might reasonably want to know the time frequently. Chris - 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/