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[SOLVED] Hyperthreding Ryzen 9 5950X(100-000000059)
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dpaddy
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PostPosted: Fri Jul 12, 2024 5:05 pm    Post subject: [SOLVED] Hyperthreding Ryzen 9 5950X(100-000000059) Reply with quote

I upgraded from Ryzen 7 1800X Eight-Core to Ryzen 9 5950X Sixteen-Core. Before the upgrade, top showed 16 CPUs (2 x 8 cores, because of hyperthreading in the 1800X). After the upgrade, top still shows only 16 CPUs, but I expected 32 (2 x 16 cores, because of hyperthreading in the 5950X).

Spending time with google lead me to conjecture hyperthreading is disabled on my 5950X. How can I confirm that, and if so -- or perhaps it is some of the cores rather than hyperthreading being disabled -- then how can I achieve 32 threads with all 16 cores enabled?

Motherboard ASRock x370 Taichi, BIOS P7.30, BIOS setting "SMT Mode Auto" (options are Auto or else Disabled). BIOS reports CPU Microcode A20F10/A201016
Code:
$ uname -a
Linux tux 6.6.30-gentoo #9 SMP PREEMPT_DYNAMIC Fri Jul 12 13:45:59 -00 2024 x86_64 AMD Ryzen 9 5950X 16-Core Processor AuthenticAMD GNU/Linux

Code:
 $ dmesg | grep microcode
[    0.211941] Speculative Return Stack Overflow: IBPB-extending microcode not applied!
[    0.211942] Speculative Return Stack Overflow: Vulnerable: Safe RET, no microcode
[    1.421301] microcode: CPU4: patch_level=0x0a201016
[    1.421301] microcode: CPU1: patch_level=0x0a201016
[    1.421301] microcode: CPU2: patch_level=0x0a201016
[    1.421302] microcode: CPU3: patch_level=0x0a201016
[    1.421303] microcode: CPU5: patch_level=0x0a201016
[    1.421304] microcode: CPU6: patch_level=0x0a201016
[    1.421304] microcode: CPU9: patch_level=0x0a201016
[    1.421304] microcode: CPU7: patch_level=0x0a201016
[    1.421304] microcode: CPU8: patch_level=0x0a201016
[    1.421305] microcode: CPU12: patch_level=0x0a201016
[    1.421305] microcode: CPU11: patch_level=0x0a201016
[    1.421305] microcode: CPU13: patch_level=0x0a201016
[    1.421306] microcode: CPU14: patch_level=0x0a201016
[    1.421306] microcode: CPU15: patch_level=0x0a201016
[    1.421358] microcode: CPU10: patch_level=0x0a201016
[    1.460422] microcode: CPU0: patch_level=0x0a201016
[    1.460434] microcode: Microcode Update Driver: v2.2.

Kernel is configured to load
Quote:
amd-ucode/microcode_amd_fam19h.bin i915/dg2_guc_70.bin i915/dg2_huc_gsc.bin i915/dg2_dmc_ver2_08.bin
(the i915 stuff is for Arc 770 graphics card -- having problems with that as well but will make separate post).

Online I find reference made to "creator mode and game mode" and "Ryzen master" to somehow switch between modes, but as far as I can tell that is some sort of Windoze program. :cry:


Last edited by dpaddy on Fri Jul 12, 2024 6:30 pm; edited 1 time in total
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pietinger
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PostPosted: Fri Jul 12, 2024 5:33 pm    Post subject: Reply with quote

Please check in your kernel configuration IF:

1. you have enabled this:
Code:
Processor type and features  --->
    [*] Symmetric multi-processing support


2. you have disabled this option and set an indiviual value:
Code:
Processor type and features  --->
    [ ] Enable Maximum number of SMP Processors and NUMA Nodes
    (32) Maximum number of CPUs

If yes, THEN check your syslog (with "dmesg") for a message like:
Quote:
smpboot: 64 Processors exceeds NR_CPUS limit of 32

Some AMD machines want here a higher value than you really have (I dont know why). If you have this message then set it accorfing the message.

(I have described this also here: https://wiki.gentoo.org/wiki/User:Pietinger/Tutorials/Manual_Configuring_Kernel_Version_6.6#Part_4_-_My_recommendations )
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dpaddy
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PostPosted: Fri Jul 12, 2024 6:29 pm    Post subject: Reply with quote

My problem was Maximum number of CPUs ; I now have it set to 64 and all is well. Thank you :!:
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pietinger
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PostPosted: Fri Jul 12, 2024 7:59 pm    Post subject: Reply with quote

You are very Welcome ! :D
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