From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <45533582.40808@domain.hid> Date: Thu, 09 Nov 2006 15:04:50 +0100 From: Gilles Chanteperdrix MIME-Version: 1.0 Subject: Re: [Xenomai-help] Strange results with latency test References: <20061109133632.GA4205@domain.hid> In-Reply-To: <20061109133632.GA4205@domain.hid> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit List-Id: Help regarding installation and common use of Xenomai List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: xenomai@xenomai.org Matthias Fechner wrote: > Hi, > > I tested today Xenomai on my AMD64 (32-bit mode) with the latency > program from the testsuite and I got for lat min negative values. > > Can my computer predict the future? :) The expiration time of a timer is usually known in advance, so, in that sense, your computer predicts the future. > > How can I interpret these values? It means that Xenomai anticipates, that is, the timer is programmed to tick a bit early in order to account for the interrupt and scheduling latencies. In your case it is a bit too early, you can change this anticipation time at compilation time with the configuration constant CONFIG_OPT_TIMING_TIMERLAT and CONFIG_XENO_OPT_TIMING_SCHEDLAT, or change it at run time by writing a new value in /proc/xenomai/latency. -- Gilles Chanteperdrix