On Friday 17 October 2014 15:04:08 Javier Ros did opine And Gene did reply: > Thanks for your answers. > > This looks like an important problem to me, looking at the foreseable > future Artificial Vision is going to have a preeminent role everywhere. > I expect machines including CNC controls making some use of it, anv > envision some CNC paradigm changes, leaded by this "revolution". > > As from LinuxCNC manual page, it says: > > .... > DESCRIPTION > hal_create_thread establishes a realtime thread that will execute one > or more HAL functions periodically. > All thread periods are rounded to integer multiples of the hardware > timer period, and the timer period is > based on the first thread created. Threads must be created in order, > from the fastest to the slowest. HAL > assigns decreasing priorities to threads that are created later, so > creating them from fastest to slowest results > in rate monotonic priority scheduling. > ... > > So it is rate monotonic scheduling. > > So I think that the slow task, no matter how slow, will get scheduled. > The only requirement, would be to get the period for the slow thread, > big enough recording and, so that it can finish with the image > grabbing processing. > > It would be nice to know, if opencv has been written with real time in > mind, so that memory allocation, pagefaults "et al." works in a > compatible way can be taken away from the show time. > > A interesting question would be to know, how well multicore procesors > are taken advantage by LinuxCNC HAL. Let say, can we reserve a couple > of processors ans schedule different threads in different cores?. > Would HAL execute different functions in the same thread at different > cores?. > > Data point only.
Box is atom D525MW, using isolcpu's. Even with a 40 kilohertz base thread, a 4 kilohertz servo-thread works well. But it did not do a thing for the noise from the encoder other than make it fast enough I could lowpass filter it a bit without mucking with the PID stability. Now I have a 5i25, no base-thread, still works well at 4 kilohertz. > Thanks very much for your answers. I apologize for my late reply :), > > Javier > ----------------------------------------------------------------------- > ------- Comprehensive Server Monitoring with Site24x7. > Monitor 10 servers for $9/Month. > Get alerted through email, SMS, voice calls or mobile push > notifications. Take corrective actions from your mobile device. > http://p.sf.net/sfu/Zoho > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> US V Castleman, SCOTUS, Mar 2014 is grounds for Impeaching SCOTUS ------------------------------------------------------------------------------ Comprehensive Server Monitoring with Site24x7. Monitor 10 servers for $9/Month. Get alerted through email, SMS, voice calls or mobile push notifications. Take corrective actions from your mobile device. http://p.sf.net/sfu/Zoho _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
