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PC Processors

aalmutairi
Journeyman III

MPI detects half of the physical cores on Ryzen Threadripper 3990x

I am using AMD threadripper 3990x in my PC running Windows 10 Pro (v.10.0.19041.329). Initially I was interested in using some simulation software that utilizes MPI. Hence, I decided to resort to WSL2 and Ubuntu linux (v.20.04). There I noticed the following when use the command lscpu:

Architecture: x86_64
CPU op-mode(s): 32-bit, 64-bit
Byte Order: Little Endian
Address sizes: 48 bits physical, 48 bits virtual
CPU(s): 64
On-line CPU(s) list: 0-63
Thread(s) per core: 2
Core(s) per socket: 32
Socket(s): 1
Vendor ID: AuthenticAMD
CPU family: 23
Model: 49
Model name: AMD Ryzen Threadripper 3990X 64-Core Processor
.
.
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As you can see, it only detected 32 physical cores (64 logical ones). I initially though it was just a WSL2 issue so I tried hyper-V but to no avail. So I assumed it is an issue of virtualization since Windows correctly detect 64 physical cores (128 logical ones). However, I tried to run mpi directly on Windows (knowing that it is not the best). The result was the same, even on native Windows, MPI (with provided by openmpi or MPICH) always detects 32 cores. I tried asking through the Microsoft WSL2 GitHub page but no one seems to know how to fix it. I tried contacting the support on AMD and they recommended asking here. Has anyone experienced something similar? and are there any fixes I can test? 

Thank you

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51 Replies

Dear hardcoregames™‌, BIOS is updated but still issue persists 

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aalmutairi wrote:

Dear hardcoregames™, BIOS is updated but still issue persists 

grab CPU-Z and post a screenshot of what it has to say

paint 3d can crop a screenshot

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what information does CPU-Z provide? 

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sorry for the question but I just reset my machine and seeing how windows is extremely fragile, I am trying to minimize the thing I install if they are of no use. 

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CPU-Z a lot of details about a CPU.

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I am assuming you are interested in this tab

pastedImage_1.png

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I need the CPU tab

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pastedImage_1.png

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misterj
Big Boss

aalmutairi, some comments.  I think it is clear that your current core count problem is a Linux problem.  When that gets corrected, you can test again.  In the meantime why not boot Linux directly into your 3990X.  AMD talks about Red Hat, but I could not find any 3990X drivers:

pastedImage_6.jpg

I have worked to reproduce the lost Ethernet problem without luck.  If you will provide more detail, I will try again.  The next time I will exit my Antivirus because it complains too much and isolates Linux and WSL.  In the meantime, if you encounter this problem, please try these two commands:

Netsh int ipv4 reset

Netsh int ipv6 reset

After both commands (perhaps with a few errors), please reboot and see if your Ethernet is back.  Thanks and enjoy, John.

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misterj‌, initially I though the same thing but when I ran windows 10 as a VM and got the same issue I realized it was a virtualization issue. In term of running linux directly, I am currently considering this option (running CentOS since it is RHEL distro of sort) but as the analysis tools I need runs on windows, it will be annoying to switch back and forth. 

The internet issue has been resolved by reseting the system, but I will try these commands if it shows itself again (hopefully not.  

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Thanks, aalmutairi.  I do not understand this:

...when I ran windows 10 as a VM and got the same issue...

I asked you to run CB under Hyper-V and it ran fine, exercising all 128 logical cores.  Is this not true?  How did you reset W10?  Here?:

pastedImage_4.jpg

Thanks and enjoy, John.

EDIT: Found this about CentOS on 3990X - Family 17.

EDIT: Apparently I am wrong.  The funny thing is Hyper-V sees all 128 logical cores, but CB only exercises 64 of them with the other 64 just messing around.  It is more like CB does not see all 128.  What version of CB were you running?  If not R20, please rerun test with R20.

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My reply got caught in a 'Currently being moderated.' 

I am wrong.  What version of CB were you running?  If not R20, please rerun with R20.  Thanks and enjoy, John.

EDIT: Very explicitly:  Create a W10 VM for Hyper-V with 128 logical cores.  Run the 64 version of CB R20.  Post a screenshot of the Task Manager-Performance tab-CPU Logical Processors.  Thanks.

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