On Saturday 08 June 2019 01:18:21 am deloptes wrote: > Gene Heskett wrote: > > BOOT_IMAGE=/vmlinuz-4.9.0-9-rt-amd64 > > root=UUID=0e698024-1cf3-4dbc-812d-10552c01caab ro > > Gene, > I can barely follow your problems with Stretch. I am just amazed how > this could be that hard. I was wondering if you possibly copied > configurations from your jessie, or is it related to the linuxcnc > distro. > It could be. And the linuxcnc developers/spinners are being made aware of these problem's also. That particular kernel you see above I will state, has the best latency figures I have ever seen on this particular machine, which with a normal kernel is so horrible I'd never consider actually running a machine with it. Milliseconds of lag normally. But latency-test shows about 20 microseconds. So one could even run software stepping, slowly but it would run. Would be great if the stepping was offloaded to an accessory pci card. Normally we use intel cpu's because their latency-test figures can be as good as 4 microseconds for a puny powered atom board. Intel has of course disco'ed that particular board, and I wish I had bought more of them when they were available.
But we normally need more than the 17 lines we can get from a parport to do a good job of controlling things. To that end a Mesa 5i25 card in a pci slot, can give us 34 control lines on 2 breakout boards, or sub a Mesa 7i76 for one of the breakouts which gives us up to 4 stepper drivers, 16 other outputs heavy enough to drive small relays, 1 3 line ABZ encoder input and 32 other inputs, more than enough to control a tool changer, work pallet loaders, whatever we can dream up. And for carving furniture parts, some of the jigs can get pretty complex with their own motors to be controlled. > Last time I had massive issues was at the time of woody-sarge-edge. Thats a while back. Wheezy has been great for us, but all good things must come to and end, if only because newer hardware demands it. So we are having growing pains, some of which are directly related to our realtime kernel needs. And there have been times in the past where we've had to disable PAE on 32 bit installs because the PAE latency was bad, same for a full 64 bit install, the bigger stack frame = lots more latency. Linuxcnc itself is growing as we find and fix bugs and add abilities. Since it can control virtually any machine, it is more complex than the commercial offerings designed for a single machine. Not well known, the utube videos have been taken down, but Toys TRO engines are (or were, they've been secretive about it) carved from a solid block of alu by linuxcnc. No commercial software can do that without moving the partially carved engine block around to other machines to do a specific operation. Capable of running a 9 axis machine, its was at one time considered munitions subject to export controls. > regards 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>
