From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261797AbVFMQsl (ORCPT ); Mon, 13 Jun 2005 12:48:41 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261855AbVFMQsk (ORCPT ); Mon, 13 Jun 2005 12:48:40 -0400 Received: from zcars04e.nortelnetworks.com ([47.129.242.56]:42918 "EHLO zcars04e.ca.nortel.com") by vger.kernel.org with ESMTP id S261797AbVFMQs3 (ORCPT ); Mon, 13 Jun 2005 12:48:29 -0400 Message-ID: <42ADB8D1.9090503@nortel.com> Date: Mon, 13 Jun 2005 10:48:17 -0600 X-Sybari-Space: 00000000 00000000 00000000 00000000 From: Chris 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: quade CC: linux-kernel@vger.kernel.org Subject: Re: latency error (~2ms) with nanosleep References: <20050613133047.GA11979@hsnr.de> In-Reply-To: <20050613133047.GA11979@hsnr.de> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org quade wrote: > Playing around with the (simple) measurement of latency-times > I noticed, that the systemcall "nanosleep" has always a minimal > latency from about ~2ms (haven't run it all night, so...). It > seems to be a systematical error. Known issue. The x86 interrupt usually has a period of slightly less than a ms. It will therefore generally add nearly a whole ms to ensure that it does not ever wait for *less* than specified. Chris