From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <4A0040D9.60907@domain.hid> Date: Tue, 05 May 2009 15:36:25 +0200 From: Gilles Chanteperdrix MIME-Version: 1.0 References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Subject: Re: [Xenomai-help] gatekeeper/0 List-Id: Help regarding installation and common use of Xenomai List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: henning.richter@domain.hid Cc: xenomai@xenomai.org henning.richter@domain.hid wrote: > Hi, > > running a xenomai task in which I am sending a single Frame (size ~500 > byte) from my EtherCAT Master to some Beckhoff slaves has latencies around > 200 us. > While running that task, top shows that gatekeeper/0 (with RT priority) has > 30% CPU usage. > What is the task of this gatekeeper and can this cause my high latencies? The gatekeeper is used when a taks is migrating from secondary mode to primary mode. The gatekeeper itself can not cause the high latencies, but the fact that a task runs in secondary mode can. To check if this is what happens, check the MSW column in /proc/xenomai/stat for the thread which has latencies issues. If MSW is increasing then you have a problem. To find where your thread switches to secondary mode, use the technique demonstrated in examples/native/sigxcpu.c. -- Gilles.