Weird bug with dual xeon and Body Force

[Zakkorn]

Today I wanted to test the Body Force.
So I made a simple scene that 4 different filled meshes, thus 4 different body forces, will move and fill another object using another body force.
That worked on a i7 4core CPU.

But when I returned home and tried on my Dual Xeon 2690 v3 it never started.
After many tries I found that the body forces made the simulation almost never to start.
I had to have maximum of 2 Body Forces for the simulation to work.
All this happened with the latest 3.002 version.

I reinstalled 3.001 and while it work with all Body Forces, it takes 6-8 times more time than with 4core.

Regards,
Zach

[georgi.zhekov]

Hello,

Can you send us the scene that is problematic with the many Body Forces? You can attach it here or send it to support@chaosgroup.com with a link to this thread.

As for the slower simulation - Phoenix FD is very sensitive to the memory transfer and if all the NUMA nodes are used, performance might decrease due to low bandwidth between the different nodes.

[Zakkorn]

I just send the scene with the issue.

I know that the Numa can do slower simulations but in almost every simulation I have done its if not the same speed at least a little faster than the 4core i7.
I also test it in both Max 2017 and 2016. Same issue.

Regards,
Zach

[georgi.zhekov]

Thanks, we got the scene and will see where the problem is.

[Guest]

Hi!

We have found no errors or something suspicious with your scene and the simulation. It ran smoothly to the last frame. So, can you give us more specific information about that issue? For example: Is there something abnormal in CPU usage?

[Zakkorn]

When I simulate in my Dual Xeon the CPU hits above 90% and brings the whole system to its knees. But it never begins to simulate.
Also if somehow stop the simulation (somehow because its almost impossible due to uber slow response and it has to simulate at least a frame to be able to pause or stop it), Max still uses above 90%. So the only way to stop it, is to terminate Max through Task Manager.
This happens only in this scene that I have more than 2 Body Forces and the grid size is 0.17cm.
If I reduce the Body Forces to 2 or put the size above 1cm it works but still not as fast as it should. (about 4-5 times slower than it should)

This happens only on the Dual Xeon system.

Regards,
Zach

[Guest]

Would you send the Phoenix .log file, please? You should do this at the moment when the system suspends.

Thank you!

[Zakkorn]

I sent the file.
I hope is the right one
Its a .slog file.

It takes more than 7 mins to calculate a frame and at the same time the whole sytem is halted.
While in every simulation I have done I can do whatever I want while it calculates. As its not using all the threads. Usually it uses 20-30% of cpu power
The i7 4core it takes between 35-45 sec per frame
So its not normal

Regards,
Zack

[Svetlin.Nikolov]

Ah, nice, so it's not a crash, but something works very slowly. Then the log would be even more helpful to track it down - the scene works fine on our Xeons, so it would be a more tricky issue. Unfortunately this is not the log we're looking for - check the Phoenix Preferences dialogue in the Simulator rollout - you can go to the Phoenix log location from there.

Cheers!

[Zakkorn]

I had a feeling that I sent the wrong file.
I will send it as soon as I get home. As I am at work right now.

I hope with the help of this file to nail down the cause of the issue.

Regards,
Zach

[Svetlin.Nikolov]

Thanks a ton! This definitely needs to be fixed.

[Zakkorn]

I just send the file (the right one this time)

If you find solution to this issue I will thank you a Megaton not just a ton

Regards,
Zach

[Svetlin.Nikolov]

I will retreat to my shelter now...

[Zakkorn]

Any news, Svetlin?

Regards,
Zach

[Svetlin.Nikolov]

Hey - I'm sorry, I got buried under unexpected tasks for a few days. Still can't get the simulation to completely lock, but it takes quite a while to get going anyway and simulates fairly slowly with many body forces, so I'll see what can be done about that and will ping you when the changes are in the nightly so you'll be able to try them out