On 2016-03-16 17:50, John Dammeyer wrote: >> -----Original Message----- >> From: Peter C. Wallace [mailto:[email protected]] >>> The ARMs and current crop of PCs are orders of magnitude faster and more >>> powerful so why is it that the real time part of Linux isn't the defacto >>> standard for Linux. If it were wouldn't the latest LinuxCNC run on just >>> about anything? >>> >>> Seems a simple question. Is there a simple answer? >>> >>> John Dammeyer >>> >> >> Preempt-RT will be mainlined into stock linux fairly soon now so its just >> becomes a kernel config option but I doubt real time kernels will ever be >> standard for common desktop distributions as they typically have >> lower performance (excluding latency) than non RT kernels >> > Lower performance? That seems like an urban legend rather than fact. Or to > be more precise, when a bench mark is run on the Preempt-RT it runs slower > than on the current standard system. And given the speed of processors > and that memory, disk and display are the limiting factors how is that even > valid for CNC systems? Even on desktops. Is the Linux world so focused on > video games that require optimum graphics performance. > > The push (and market) in both the windows CNC world and clearly in the > LinuxCNC is for external hardware to do the physical real time part for > stepping and encoders especially for new hardware. Like the MACH3 world for > people happily running LinuxCNC turning out parts are treating their > equipment like a tool. If the tool isn't broken and does the job most won't > replace it. > > In either case that turns the main box part into something that is nothing > but a trajectory planner and a graphical display interface. All it has to > do is provide the motion information to the control part in a timely > fashion. > > John Dammeyer >
The problem is different. RT means looking around and fulfill all tasks in a defined timeslot. Performance means in most cases move data as fast as you can. And in some cases it's mutually exclusive. > > ------------------------------------------------------------------------------ > Transform Data into Opportunity. > Accelerate data analysis in your applications with > Intel Data Analytics Acceleration Library. > Click to learn more. > http://pubads.g.doubleclick.net/gampad/clk?id=278785231&iu=/4140 > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users -- "In der Wissenschaft siegt nie eine neue Theorie, nur ihre Gegner sterben nach und nach" Max Planck ------------------------------------------------------------------------------ Transform Data into Opportunity. Accelerate data analysis in your applications with Intel Data Analytics Acceleration Library. Click to learn more. http://pubads.g.doubleclick.net/gampad/clk?id=278785231&iu=/4140 _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
