I took a moment and looked at that thread. Those numbers are worst case. Another posted ~2us with little load. It would be nice to set up a latency tester which artificially mucked with some threads to get realistic numbers.
Hmmm... is there any instrumentation in the simulation code to calculate latency statistics with actual setups and configurations? That would be rather interesting... On Mon, 10 Sep 2012 19:55:58 +0200, Michael Haberler wrote: > Alex dug this out on Xenomai on the Rpi and it is an interesting > read: > http://www.raspberrypi.org/phpBB3/viewtopic.php?t=12368&p=154691 > >> A quick (very quick) test shows typical latencies in the order of >> 20-30uS and peaking at ~70uS for user space tasks. The kernel space >> latencies are even better and look pretty solid at around 15uS. > > That could mean Rpi+Xenomai is actually usable with soft stepgen > (assuming it doesnt run out of steam on doing FP in motion) > > also it seems this kernel has the hires timer issue resolved: > >> If power management is enabled, the 1MHz System Timer will be used. >> If power management is disabled, the ARM Timer, configured to run at >> 250MHz, will be used instead. > > -m > > Am 10.09.2012 um 18:48 schrieb Jon Elson: > >> Michael Haberler wrote: >>> here's linpack figures for the Rpi and an Intel D525. >>> >>> the D5252 is almost a factor of 6 faster than the Rpi for this >>> benchmark >>> >> Thanks much for doing this! Not a great result, though. My feeling >> is >> that the >> Atom processors are marginal for LinuxCNC, especially in cases with >> long >> programs or contouring, where the slowness would be more obvious. >> So, if the Pi is 1/6th that speed, that will not be good at all. >> Exactly how this compares on LinuxCNC, where there is also a lot of >> non-FP code, isn't clear. If LinuxCNC was run with the GUI on >> another >> system, it might be OK, and for special projects which are not >> typical >> machines, it might be fine. ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
