Hi Doug, Yes, it's still all real-time. To measure CPU usage, I just ran bogomips in user space. This tells me how much CPU is left over after all the higher priority tasks take their cut. If M is the score when the system is unloaded, or reported during boot, and m is the score when EMC is up and doing a rapid move, I know that the fraction of CPU consumed by the real-time tasks is <= (M-m)/M. Uncertainty remains about just how fast you can go, however, because quickstep's critical work isn't quite evenly distributed across PERIODs. I don't think it's too far off, though. On a slower machine, I guess that it's probably safe to decrease PERIOD until the real-time work eats up half the CPU. A really fast machine may hit some limit in the capabilities of the interrupt hardware first. -- Matt