On Thursday 31 October 2019 04:35:53 Håvard Flaget Aasen via 
Emc-developers wrote:

> Hello
>
> I have seen this come up a couple of times. If Sebastian wants it, I
> can spin up a vm with a buildbot-worker in buster. I have read through
> http://buildbot.linuxcnc.org/buildslave-admin-guide.html and it didn't
> look to hard to get one up and running.
>
> I hope 2 cores and 2 GIB of RAM is enough to get something acceptable
> out of it.
>
I've not gone that far, but after findiing I got better latency with only 
one core reserved for isolcpus, the 3 left for debuild can make a new 
copy of master in under an hour, so thats wnat I've done here 3 or 4 
times now. Currently running 2.9.0pre quite well. If that can be tied in 
with the buidbot to be visible as the pi4 version of armhf, I'd have no 
objection to doing it.  Its running on my pi4 so well I'd like to see it 
happen.  Its running my lathe with far fewer latency excursions than I 
am experinceing on a D525mw intel board. And its actually doing more, as 
its serviceing two jog dials that don't exist on the wintel boxes, and 
compensating for bed wear as it moves z. But is not yet servicing a 
coolant misting system thats 20 minutes from doing a smoke test on one 
of the wintels boxes. All that remains for that is actually powering the 
circuit.  And determining if I'm turning the pump in the right 
direction. Murphy has residency here. :)

Or, I've considered ordering 2 more 2Gig pi4's with the thought of 
sending Sam one of them if he is willing to add it to the buildbot farm.  

IMO the orginal choice of an odroid, with its hard coded UEFI boot 
limited stuff was not a good choice. Even a pi3, as slow as it is, can 
and has built linuxcnc in around 4 hours, and kernels in 7 or 8 hours. 
all it needs added to a raspian install is to kill the swapfile, adding 
a few gigs of swap on a 40 dollar ssd to its fstab, and use the rest of 
that ssd as workspace so its not pounding on the boot u-sd. It would be 
slow and would depend on finding a sata to usb adapter that works on 
usb-2 stuffs. Haveing usb-3 on the pi4 to feed the ssd speeds things 
considerably.

Sam?

AFAIAC, the pi4 has arrived and should be considered for new builds, its 
running my stuff as well or better than the wintel stuff is right now.
latency-test figures aren't as good, but the overruns have disappeared.
Example, it ran long enough to cut a lathe-pawn out of air, here is the 
shutdown report:

Shutting down and cleaning up LinuxCNC...
task: 87438 cycles, min=0.000074, max=0.058256, avg=0.010096, 0 latency 
excursions (> 10x expected cycle time of 0.010000s)

I don't, out of 3 other intel boxes, have a computer that can claim that.
And you can have that preempt-rt kernel, and the linuxcnc I am running on 
that 2G rpi4 from my web page, just add:

lathe-stf/linuxcnc4rpi4

to the address bar and hit return once you see the front page pix.
 
> Håvard

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)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page <http://geneslinuxbox.net:6309/gene>


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