From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <46C2D5C4.2010407@domain.hid> Date: Wed, 15 Aug 2007 12:30:28 +0200 From: Wolfgang Grandegger MIME-Version: 1.0 References: <46C02829.9020009@domain.hid> <46C04384.4030805@domain.hid> <46C05180.5090302@domain.hid> <46C05690.2010108@domain.hid> <46C063E0.1010809@domain.hid> <46C07005.8000504@domain.hid> <46C1B498.8060600@domain.hid> <46C1EE69.3020301@domain.hid> <46C1FFDA.4070709@domain.hid> <46C298FD.8070300@domain.hid> <46C2B842.1080501@domain.hid> <46C2CC73.9080807@domain.hid> In-Reply-To: <46C2CC73.9080807@domain.hid> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Xenomai-help] [Ethercatmaster-users] EML conflict with RTCAN? low_level_input framebuilding failed. List-Id: Help regarding installation and common use of Xenomai List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: rolandtollenaar@domain.hid Cc: Xenomai-help@domain.hid, EML users , Jan Kiszka , rtnet-users Roland Tollenaar wrote: > Hi, > > Some more interesting findings (no i-pipe trace yet though). > >> Hmm, this doesn't convince me yet. Such skews during startup may as well >> be triggered by unusual load during runtime (non-RT activity or new RT >> components). Did you put your system under adequate non-RT load as well >> while measuring the outputs? > Running latencytest with my application shows an average latency of > about 40 and a max of 200ns. This was rather shocking so I turned off > rtcan in my application. Now the max latecy is 60ns. Turn off EML and > turn on rtcan, max latecy is 230ns. How is that for strange? But since I > can see the scope output bobbing with 200ns during the latency test, I > can also see that if I run my application without the latency test the > huge max latency disappears entirely. Maybe it is time for the trace but > then again I am still using CAN over the parallel port so will see what > it does on a machine with a PCI CAN adaptor first. Because I think I > know what happens: Due to the external loading the CAN recv interrupt > triggers the Rx ISR briefly before the 1ms task period ends. Due to the > priority of the ISR (huge debate over this) and its atomicness (if I > remember correctly) the reading out of the slow hardware delays the > start of the new task period. > > Just thought it was interesting to mention. Btw when the latency appears > there are no overflow messages or anything like that which support the > theory I have about the cause. > > Btw2 the 200ns latency spikes do not cause the scope to loose lock on > the saw-tooth so whatever causes that problem is of a different nature > still. s/ns/us/ ? Wolfgang.