Poor Parallel Performance I9-13900

[GOMC]

Hello all.

We have an I9-13900 CPU that is totally underperforming compared to much older CPUs, such as the i5-8600K.  We are running a computationally intensive piece of software that we wrote (C++) that uses OpenMP for parallelization.  On any other CPU, it will run with100% utilization of 4 cores.  But running on 4 cores of this i9-13900 CPU gives about 45% utilization (with very slow total runtime compared to older CPUs). 

We are running Ubuntu Linux 22.04 LTS (same as on 12 other computers).   We are using the stock Intel CPU cooler, and temperatures never go above 75 C.  The computer has 32 gb of ram, and the code is not memory or I/O intensive.  I disabled all of the efficiency cores, but that had little effect on the computational performance. 

The picture is a screenshot from nmon.  On any other CPU, I have four green bars at 100%.  

Any insight or suggestions of things to test would be appreciated.  

[GOMC]

Update: I ran "stress" on 4 cores (https://www.malibal.com/guides/how-to-stress-test-your-cpu-on-linux/).  What I observed was 1-2 cores ramping up to 5.3 GhZ, with all remaining cores sitting at 0.800 GhZ.   If I run on 8 cores, the max clock speed achieved is 4.3 GhZ, with a number of cores frequently sitting at 0.8 GhZ.    The highest temperature observed was 65 C.   What is going on with this thing? 

[GOMC]

Apparently I'm not the only one with this problem.   Anyone have a solution?

https://stackoverflow.com/questions/75923768/openmp-threads-not-fully-utilize-cpu-cores-on-new-machine

[RamyerM_Intel]

Hello GOMC, 

Thank you for posting in the communities. I want to be more familiar with your system configuration to check for possible errors as such, please share with us your SSU logs. Would you be able to specify the software that you mention as well? The reason I ask is because if I understand correctly, you are experiencing while developing the software which uses OpenMP for parallelization. I will be waiting for your reply. 

Ramyer M. 

Intel Customer Support Technician 

[NormanS_Intel]

Hello GOMC,

I wanted to check if you had the chance to review the information we posted. Please let me know at your earliest convenience so that we can determine the best course of action to resolve this matter. 

Best regards,

Norman S.

Intel Customer Support Engineer

[RamyerM_Intel]

Hello GOMC,

As we have not heard a response in the past few days, we will proceed in closing this thread. Should you need assistance in the future, please submit a new question as this thread will no longer be monitored.

Ramyer M.

Intel Customer Support Technician