Isaac Sim Poor CPU Threads Utilization

[tcwjac]

Hello,

One of my CPU threads is always maxed out at 100% while the other threads are underutilized. This leads to very long loading time for opening USD scenes, examples, etc., and probably the low frame rate as well even on default scenery with the flat ground and the simulation is not running. Screenshots of detailed performances are at the very bottom.

Isaac Sim Version

[✓] 4.2.0
[✓] 4.1.0

Operating System

[✓] Ubuntu 22.04

GPU Information

• Model: RTX 3090 iChill
• Driver Version: 535.183.01

CPU Information

AMD EPYC 7T83 64-Core Processor

Detailed Description

Fresh installation of Isaac Sim 4.1 and 4.2 majorly with default settings (No ROS bridge). I have tried some solutions in Simulation Performance, i.e., physics thread count, running in Fabric via ./isaac-sim.fabric.sh. Running through Omniverse AppLauncher makes no differences for both 4.1 and 4.2.

I have also looked at Forums like Speed Up Simulation, Multi GPUs Slower Than One GPU, Nonsense with High CPU/GPU usage, Use Multiple Threads in Omniverse (not tried because that has more to do with scripting instead of baseline performance), Low FPS Issue on Isaac Sim 4.1.

Fig.1 Settings on 4.1

Fig. 2(a) Profiler

Fig. 2(b) Profiler continuation

Fig. 3 Ubuntu System Monitor for CPU

Fig. 4 Clean default Isaac Sim 4.2 executed through AppSelector with ECO Mode on as a comparison

[VickNV]

Thank you for providing detailed information about your setup and the issue you’re experiencing. To help troubleshoot and potentially reproduce the 100% usage of a specific CPU thread, can you describe the exact steps you take from launching Isaac Sim to observing the 100% CPU thread usage?

[tcwjac]

Upon a further look into the CPU utilization while idling, I realize one of the CPU threads is maxed out and will be switched by another CPU thread which becomes the new maxed out thread (see Fig. 5). This problem is likely an oversight on my part and Isaac Sim is probably not the root cause, and I should look for other information instead.

Anyway, for the launching steps, I simply launch Isaac Sim 4.1 or 4.2 through the App Selector with the settings seen in Fig. 6. When the Isaac Sim window pops up, the previous thread problem becomes more persistent as seen in Fig. 7.

For additional context, the computer has xubuntu and xrdp or GNOME installed for remote desktop control which is necessary. Unfortunately, there is no performance information available before and after setting up for remote control.

Fig. 5 Idling utilization

Fig. 6 Launch method. Same launch method and problem for 4.2, though the screenshot shows 4.1

Fig. 7 Persistent 100% peak after this Isaac Sim screen

Fig. 8 nvitop screen with some remote desktop processes. The picture shows 59.0% CPU for the first PID and appears that 100% is the maximum value, but I often see Isaac Sim app go over 200% CPU

[tcwjac]

Update:

The poor CPU threads utilization was very likely the cause of using Gnome for xrdp remote desktop connection.

After uninstalling Gnome and configuring xfce4 for xrdp, Isaac runs very smoothly and responsive.