#linuxcnc-devel Logs

Apr 11 2017

08:29 AM jthornton: what does make -j4 dep-pkg do that make -j4 doesn't do when building a kernel?
08:30 AM jthornton: opps I do make -j8 then make modules install and make install
02:59 PM CaptHindsight: has anyone ever seen latency histogram output with the distribution way off center for the servo thread?
03:00 PM CaptHindsight: it does have some positive going results but it's only a few % of overall
04:05 PM seb_kuzminsky: CaptHindsight: so that system is consistently late in running scheduled tasks? i've never seen that, but i'm not surprised that such a system exists
04:18 PM seb_kuzminsky: is this rtai? if so i think there's a tunable you can set, to schedule wakeups early by a certain time
04:19 PM CaptHindsight: seb_kuzminsky: yes, RTAI from the latest LCNC ISO
04:21 PM CaptHindsight: I swapped APU's in the system. This was a 4-core that had different results (far more the norm)
04:22 PM CaptHindsight: the new 2-core APU acts like this
04:22 PM CaptHindsight: haven't investigated further
04:25 PM CaptHindsight: it only happens on the 1mS servo thread
04:27 PM seb_kuzminsky: ask memleak ;-)
04:28 PM CaptHindsight: he took a peek at the kernel config
04:29 PM CaptHindsight: seb_kuzminsky: whats the longer term plan for future RTAI kernels shipped with LCNC?
04:30 PM CaptHindsight: well the distro in general, will it be Debian or back to Ubuntu now that they dropped Unity or?
04:30 PM pcw_mesa: I thought the histogram had to be symmetrical since it records the time between invocations (not the latency relative to a fixed time)
04:31 PM CaptHindsight: I asked memleak about getting 4.x RTAI kernels
04:31 PM pcw_mesa: so is its late one cycle the next cycle shows as early
04:31 PM pcw_mesa: so if its
04:31 PM CaptHindsight: pcw_mesa: it's symetrical but not centered at 0uS, it's more ~-6uS
04:32 PM pcw_mesa: Thats odd
04:32 PM CaptHindsight: like the baseline was shifted from the usual results, and only for the servo thread
04:32 PM pcw_mesa: I think I have seen that though
04:33 PM pcw_mesa: various minor asymmetries
04:34 PM pcw_mesa: maybe some correlation with every N cycle due beats with caching etc
04:35 PM CaptHindsight: the next funded project here that requires a 4.X RTAI kernel could provide support for future LCNC releases
04:35 PM CaptHindsight: pcw_mesa: all I did was swap APU's and I get these odd latency results
04:36 PM seb_kuzminsky: we have support for RTAI 5.0-test2 in mainline linuxcnc, i bet RTAI 4.x would take just a little work to get going
04:37 PM seb_kuzminsky: i build rtai5 kernels and tried them on virtual machines, and had weird temporary lockups that paolo and i both failed to debug, and after a while i gave up :-(
04:38 PM seb_kuzminsky: https://github.com/SebKuzminsky/rtai/commits/vulcano-debs
04:39 PM seb_kuzminsky: that's a git version of the rtai.org vulcano cvs from 2016 Aug 22, with our debian packaging and then a bunch of junky debugging attempts
04:41 PM seb_kuzminsky: it's intended to work with linux 4.1.18 with the hal-linux-4.1.18-x86-7.patch
04:41 PM CaptHindsight: memleak got tired of fixing everything for paolo without any thanks or recognition
04:42 PM CaptHindsight: so unless I fund it it's not going to happen
04:43 PM CaptHindsight: so I am trying to kill two birds with one stone by asking about the direction of LCNC
04:52 PM CaptHindsight: what kernel is Jessie or Mint Betsy up to?
04:53 PM seb_kuzminsky: i don't speak for the linuxcnc project, just for myself. i'm sympathetic to memleak's frustration with paolo
04:54 PM seb_kuzminsky: we don't currently have an rtai kernel beyond what we're shipping on wheezy, on the current live cd
04:54 PM CaptHindsight: I understand
04:54 PM seb_kuzminsky: i have no concrete plan for future rtai kernels, beyond a hope that one will materialize out of the internet somehow
04:55 PM CaptHindsight: I'm looking at the best way to get LCNC some newer RTAI support
04:55 PM seb_kuzminsky: i understand, thank you for that
04:56 PM seb_kuzminsky: i've not jumped on memleak's rtai fork, mostly because i think rtai needs a coherent developer community in order to succeed
04:57 PM seb_kuzminsky: that said, i sure understand how hard it can be to work with rtai.org, and i understand memleak being fed up with them and going his own way
04:57 PM CaptHindsight: when we start using Ryzen here we will need to update RTAI
04:57 PM seb_kuzminsky: i feel like there's no good solution to that social problem
04:58 PM CaptHindsight: it's was no longer fun so it now requires other incentives
04:58 PM seb_kuzminsky: fwiw, i think paolo and the folks at rtai.org might have changed their tune with respect to crediting contributors better since memleak stopped interacting with them
05:12 PM CaptHindsight: I understand that you'd like to use the RTAI.org repos for building but I don't see that happening anytime soon unless they copy and merge memleaks repos
05:38 PM JT-Shop: pcw_home: 7i76's in stock?
05:44 PM seb_kuzminsky: CaptHindsight: i don't understand what you mean. vulcano builds fine, and linuxcnc runs on it and passes all the tests. It's just, about 1 time in 20 there's a soft lock when unloading the rtai modules and it requires manual intervention to continue, so it's no good for the buildbot
05:48 PM CaptHindsight: screenshot of the histogram https://imagebin.ca/v/3IkSuxnTVoWH
06:30 PM pcw_mesa: JT-Shop: toward end of this week
06:31 PM JT-Shop: ok thanks, give me a shout if you remember I have a few other cards to order
07:32 PM CaptHindsight: seb_kuzminsky: sorry I misunderstood the problem
08:30 PM seb_kuzminsky: ah, ok, no problem
08:35 PM skunkworks: seems to work... https://www.youtube.com/watch?v=xmMbyJEne0Y
08:53 PM seb_kuzminsky: neat! are you going to EDM out the LinuxCNC splash screen? :-)
09:14 PM skunkworks: heh - sorry - not controlled by linuxcnc.... Yet ;)
09:43 PM cradek: heh those videos are not very exciting
09:43 PM cradek: but that's awesome you have it going
09:44 PM cradek: now you can tap anything, and also remove taps from anything
09:44 PM cradek: these machines probably have another use too, but it can't be as important
10:59 PM skunksleep: cradek: yes pretty boring.. only slightly better https://youtu.be/VkSXIi6ox7s
11:01 PM skunksleep: Now have to figure out what all the settings do. Amazing - very little electronics - hydraulic ram