Hello Hobin, thank you for your reply, i followed your advice and seperated the power source, furthermore i used another switch but it does not change a thing. There are still large jitter peaks that are periodic.
The thing is that while looking for the source of the jitter i connected the master directly to the slaves and then i get all these messages about the timed out frames. Of course i still want to know what causes the jitter, but at the moment i would really like to know why i get loads of Messages about timed aut datagrams, even in when the master is in idle mode. Does someone have an advice for me? Best Regards Christian > Hello Christian, > I experienced similar problem. In my case, it was the switch that caused > the > problem. When there were many slaves, sometimes the current to the switch > went down, and it caused datagram time-out. After all, the power source > had > to be isolated from other slaves. It took my team a lot of days to point > the > cause. Why don't you check it? > > Hobin > > On Fri, Feb 27, 2009 at 1:34 AM, Christian Gieseler > <[email protected]>wrote: > > > Hello together, > > > > I was trying to do some benchmarking with my master and came across a > > behavior that i couldn´t explain. Usually my master has a jitter of > some > > microseconds, but every approximatly 750 cycles i have a peak in the > jitter > > that is about ten times higher. First i tried to switch of any > unnecessary > > services and daemons that could cause the problems. But the result was > the > > same. Then i tried to play a bit with the cycle time, made it faster, > than > > made it slower, but still i have the same behaviour independent from the > > cycle time. So i thought that it can´t be linux that is causing the > problems > > and must have something to do with the master or my application. But in > fact > > it did not change a thing even when i strip of most of my application an > > just have the basic example running. > > > > The last thing to be changed was the switch that is between the master > and > > the slaves, and my hope was that the switch was the thing causing the > > trouble. But in fact i the get really a lot of messages about timed out > > Datagrams. If i put the switch in again ist works again, wich is not > what i > > expact since the latence should be lower without the switch. I don´t > want to > > set up the datagram timout since 500 micro seconds seem to bei quite a > lot > > form me at 1KHz and as one would expect that this is enouph a ist is ok > witz > > the switch. > > > > There is no difference if i use the stable 1.4 Version, oder the > > development branch 1.5 (Release 1667). The master runs on a debian with > > kernel 2.6.24, has an intel Pro100 nic on a pentium m without XServer. > I > > use --enable-cycles when configuring. Skipping this does not change a > thing. > > > > Can anybody give me some hints what causes the fequentlich returning > high > > jitter, and even more important, what to do against the timed out > datagrams. > > > > Best Regards > > > > Christian -- Psssst! Schon vom neuen GMX MultiMessenger gehört? Der kann`s mit allen: http://www.gmx.net/de/go/multimessenger01 _______________________________________________ etherlab-users mailing list [email protected] http://lists.etherlab.org/mailman/listinfo/etherlab-users
