On 5/16/2012 6:25 PM, Lars Segerlund wrote: > A quick question, > > I would like to ask what speed you 'guess' / estimate the stepper > lovers need ? ... and with speed I mean max allowable latency. > Perhaps I could also ask about the speed for the loop ? > > On a well tuned x86 system, a 100kHz loop speed for the steppers > should be easily obtainable, and 250+ possible, if I'm not totally > wrong. > > / regards, Lars Segerlund. > > 2012/5/16 Jan de Kruyf<jan.de.kr...@gmail.com>: >> Hallo, >> Back from a week bundu-bashing. >> I would say from my side that I see a fair amount of work in the PREEMPT_RT >> patches still needs doing. >> Besides the point that the stepper lovers will allways want the speed of >> RTAI / XENOMAI. >> >> <...> >> >> j. >> >> >> >> On Fri, May 11, 2012 at 6:10 PM, Kent A. Reed<kentallanr...@gmail.com>wrote: >> >>> <...> >>> >>>
Lars: I think most agree with your assessment of x86 systems and a 100kHz loop speed (10us cycle time) is already faster than many of the existing systems with software step generation that I've seen discussed. However, latency is the key issue in software step generation. The numbers can't easily be discussed in the abstract because the behavior of the attached stepper drive also enters the calculation. You can read, e.g., http://wiki.linuxcnc.org/cgi-bin/wiki.pl?TweakingSoftwareStepGeneration for one description of the considerations. Bottom line is that systems with latencies over 100us are considered unworkable for software step generation and we strive for latencies under 25us. The recent Intel Atom-based integrated motherboards are yielding latencies below 10us with our RTAI-enabled kernel. Regards, Kent <http://wiki.linuxcnc.org/cgi-bin/wiki.pl?TweakingSoftwareStepGeneration> ------------------------------------------------------------------------------ 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 Emc-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-developers
