Isaac Sim time step

[heena.hyun]

Isaac Sim Version

4.5.0
4.2.0
4.1.0
4.0.0
4.5.0
2023.1.1
2023.1.0-hotfix.1
Other (please specify):

Operating System

Ubuntu 22.04
Ubuntu 20.04
Windows 11
Windows 10
Other (please specify): Ubuntu 24.04

CPU

AMD Ryzen 9 7900X 12-Core Processor

GPU

GeForce RTX 4090

Memory

125G

Question

Hello,

I want to perform physics calculations every 500Hz and display them on the screen. However, I’m confused because there are multiple time step-related items in the app, so I’d like to ask a question. To achieve my goal of performing calculations at 500Hz as intended, which of the following should I change?

Physics Scene > Time Steps Per Second
Root Layer > Time Codes Per Second
Min Simulation Frame Rate

Currently, I’ve changed both Time Steps Per Second and Time Codes Per Second to 500, but the robot falls strangely slowly, as if time is flowing slower than real time.

I’d appreciate your help.

Thank you.

[VickNV]

Could you first monitor your system performance (e.g., CPU/GPU usage) to ensure your hardware can handle the increased computation load at 500Hz?

[heena.hyun]

This is monitoring information while running the standalone script.

~$ nvidia-smi
Tue Apr 1 11:20:27 2025
±----------------------------------------------------------------------------------------+
| NVIDIA-SMI 550.120 Driver Version: 550.120 CUDA Version: 12.4 |
|-----------------------------------------±-----------------------±---------------------+
| GPU Name Persistence-M | Bus-Id Disp.A | Volatile Uncorr. ECC |
| Fan Temp Perf Pwr:Usage/Cap | Memory-Usage | GPU-Util Compute M. |
| | | MIG M. |
|=========================================+========================+======================|
| 0 NVIDIA GeForce RTX 4090 Off | 00000000:01:00.0 Off | Off |
| 31% 44C P2 116W / 450W | 4896MiB / 24564MiB | 61% Default |
| | | N/A |
±----------------------------------------±-----------------------±---------------------+

±----------------------------------------------------------------------------------------+
| Processes: |
| GPU GI CI PID Type Process name GPU Memory |
| ID ID Usage |
|=========================================================================================|
| 0 N/A N/A 1847 G /usr/lib/xorg/Xorg 10MiB |
| 0 N/A N/A 19804 C+G …/hn/isaacsim/kit/python/bin/python3 4852MiB |
±----------------------------------------------------------------------------------------+

[heena.hyun]

I set
Physics Scene > Time Steps Per Second : 500
Root Layer > Time Codes Per Second: 500

Then I expected Frame time will be 0.002, but it shows like 8.5~10ms.
What do I need to do to get 0.002ms?