Lubuntu 18.04

I'm working on getting rt preempt going on the light weight minimal install of Lubuntu 18,04. I built and installed the 5.0.14-rt9 #1 SMP PREEMPT kernel but oddly synaptic package manager does not see it nor will it allow me to delete all the generic kernels yet the grub customizer sees it. Maybe it's just too new for Lubuntu 18.04... I'm going to back down to 4.x.x-rtx in the morning and build that and see. Another interesting thing is the latency test runs in non realtime so it can't find it either. When I do uname -a it shows the rt kernel is the one running.... if anyone else is running Lubuntu 18.04 and wants to share some notes that would be a big help.

JT

For any debian based system, synaptic will only show installed debian packages. If you install using make install or such, it won't show in synaptic.

if uname -r shows that the rt kernel is the one running then that is what is running. As far as removing all the rest - synaptic may not let you remove every kernel - but I don't know for sure.

mozmck wrote:

if uname -r shows that the rt kernel is the one running then that is what is running. As far as removing all the rest - synaptic may not let you remove every kernel - but I don't know for sure.

The first issue might be that the kernel is not "fully preemtable", or lubuntu might have some issues with it as I had the same problem with lubuntu 16.04 when it came out and had to jump some hoops to make it work but unfortunately I can not recalled what I did then and have not used Ubuntu since then.
Removing kernels from synaptic will not work as expected as it has a fail safe so it will install the current generic kernel whenever trying to remove another one.

mozmck wrote:

For any debian based system, synaptic will only show installed debian packages. If you install using make install or such, it won't show in synaptic.

if uname -r shows that the rt kernel is the one running then that is what is running. As far as removing all the rest - synaptic may not let you remove every kernel - but I don't know for sure.

I just looked on my LinuxMint 18 in Synaptic and sure enough no rt kernel. I guess I was thinking Debian and working in Ubuntu lol. Anyway I'm going to back down to 5.0.3-rt1 kernel and install that as Peter is using that now with Ubuntu 18 so I know that works. I should have known better than to use the latest one.

uname -r shows the 5.0.13-rt9 is the kernel running but for some strange reason latency test can't find it.

JT

Ok, I got everything sorted out and backed down a few notches on the kernel and I have LinuxCNC up and running in Lubuntu 18.04 with very surprising low latency running the servo thread so far it's been running for an hour or better and the latency is 8,434 ns. Much better latency than Debian had.

I'll update my Uspace web pages in the next day or so with what I did to get up and running.

JT

Some interesting latency results both from the same motherboard etc only the OS is changed.

First Debian 9


Now Lubuntu 18.04


Quite a difference it seems... Lubuntu is not the holy grail of OS's as being light weight it has it's own problems with some of the support programs like LeafPad and the file manager but I think overall it's quite usable on a machine.

Next I'll install QtPyVCP and see how that goes with VTK plotting much faster than Gremlin it should scream.

JT

Did they by any chance fix the problem of copying large files on Lubuntu 18.04 ?
And as for light it is not by any standards, Debian netinstal with Mate is much snappier.
Due to lack of time I did not get a chance to try to install Linuxcnc on Porteus as that is the light weight king of Linux distros, while maintaining full functionality. They even have a version for 486 processors with Mate desktop! Magnificent, especially since I already dug out a 486 notebook and some pentium 1 notebooks from when I had still black hair!