Number of regions and stability

[Draconis]

Hello Geir,
A new question.
Reminder of my configuration:
Paspberry PI 4 - 4GB; NVME disk M2 expansion card
32-bit Raspbian OS
MONO version: Mono JIT compiler version 6.12.0.107
OpenSim on PI 09/21/2020

As I said previously the whole works really well.
I still have a problem, or maybe this is normal. i don't know
I can only have 2 active regions, because as soon as I create a third region the simulation crashes in a few minutes.
After multiple tests, this is the conclusion that I made.
for my test I created a simulation with regions without anything above. 0 build - 0 scripts.
2 regions: ok - 3 regions: crash
the pre-crash messages are not exactly the same but are still around MONO.
Do you have an idea ? Is there a solution to have more than 2 regions?

I wish you a good day

 

[Draconis]

I am completing my question.
Actually with 2 regions, a few builds and scripts, I have the same problem. After a few minutes or a few hours, it's random, it always ends the same way.
I attach the screens.
After reading various posts on the forum, I tell myself that it must finally come from my version of Mono. what is your opinion ?

 

[Geir Nøklebye]

Are you running standard regions (256x256 meters) or VAR regions?

On one of my PIs I have two simulator instances running; one with 4 standard regions and the other with 5 for a total of 9 on the same PI. It is all running very stable.

However, if you try and run multiple VAR regions in the same instance things gets very flaky and fast. This is the nature of the VAR beast, and not specific to the PI.

 

[Geir Nøklebye]

The question is also what version of the kernel you use on the PI and which firmware version.

I enable the 64-bit kernel on /boot/config.txt which is done my adding the line
arm_64bit=1
at the end of that file. That makes the kernel use the full range of memory in your PI.

I have also upgraded to this kernel:
5.10.17-v8+ #1403 SMP PREEMPT Mon Feb 22 11:37:54 GMT 2021 aarch64 GNU/Linux

Instructions can be found in their forums, (it might even be standard on the Raspbian OS release they made in January 2021).

In addition I have added the following lines to .profile on the account that runs the simulators:
ulimit -s 1048576 ulimit -n 2048 export MONO_GC_PARAMS="nursery-size=32m" export MONO_GC_DEBUG="" export MONO_THREADS_PER_CPU=8

Not sure if the first two actually makes a difference.

 

[Geir Nøklebye]

Another thing to remember is that you are only running 32-bit mono so there are limitations on how much you can stuff a region with prims, scripts and physical objects before mono runs out of memory. I think the limit is 3 GB memory per application, or in this case each instance of mono on the 32-bit Raspian OS.

On an 8 GB Pi, you should be able to run 3 simulators each using up to 2.5 GB each for a total of 7.5 GB with the rest for the operating system.

If you have heavy loaded regions, you can create multiple simulator instances and distribute your regions across them. They will all compete for the total memory your PI has, but each simulator is less likely to run out of memory that way.

 

[Draconis]

Good evening Geir,
Thank you for these answers, because I am starting to despair. The more I do different tests, the less things work.
For information I am more of a "Windowsian" than a "Linuxian". It's been a long, long time since I ditched the linux versions for the convenience of Microsoft .
Something else a good part of your answer is Chinese for me. So if that is possible, I would need more details to what I have to do for the most stable set possible.
As you know I would like to create a real grid with a mother computer and some raspberry daughters as support. I don't want to let go, but I need more elements . I leave it to you to know what I need to know.
The detail I can give you is that the raspian that I installed is the full 32 bit (office suite, games etc.)
Installed at the end of December 2020 (just after Christmas )
while you answer my questions, I uninstalled mono 6.12 to try to replace version 6.0.131 but without positive results with opensim version 0.9.0.0, 0.9.0.1 etc. I have the impression that everything is working more and more poorly I think a reconstruction from the start would be more useful.

So the first question in the series: Which version of Raspian should I install?

 

[Geir Nøklebye]

Install the official Raspbian OS which is 32-bit.
The latest release was in January 2021.
I use the light version which only has a terminal interface as I run the machines headless.
See the instructions in the raspberry site to set it up from the get go with ssh enabled.

This version conserves some memory, but assumes you are comfortable working in a terminal only mode.

Once you have it going you can enable the 64-bit kernel as described in a message above.

 

[Draconis]

Hello Geir,
As I was telling you, I am not very comfortable with linux and therefore raspbian. I hope you won't be offended if I take the version with desktop but not the one with all the software that is useless.

maybe there is something i didn't quite understand:
- Exactly where to find the info to activate the arm64 kernel
- How to add the lines that you propose in .profile

O yes, you did not come across the best lol

 

[Geir Nøklebye]

You enable the 64-bit kernel in /boot/config.txt which is done by adding the line
arm_64bit=1
at the end of that file and then reboot the system which will start with the 64-bit kernel.

If you are not familiar with Linux I take it you are not familiar with vi either, so the easiest editor to use is nano which you invoke by typing:
nano /boot/config.txt
in terminal.

To edit your .profile (which most likely is a new file in your case) in terminal do the following:
cd nano .profile
then add the lines I mentioned and save the new file.

You can either
source .profile
in terminal, or simply exit the current terminal session and open a new one.

 

[Draconis]

Thank you very much for the quick response.
I think I have understood everything. it's super clear.

Next question : which version of mono should I take?

 

[Geir Nøklebye]

Unless you plan to use postgresql, you should take the latest version from here https://www.mono-project.com/download/stable/#download-lin-raspbian

Do not get the distribution version as that is an old 5.10 or something.