AnsweredAssumed Answered

Hyperthtread slower than no hyperthread

Question asked by ceusebio on Oct 12, 2020
Latest reply on Oct 17, 2020 by Thanny


i'm testing the performance of some systems wit Intel and AMD CPUs. The test consists in making renders with Arnold, Renderman and Houdini and calculate the time spent per job. With Intel CPUs everything works as expected, for a render done at 1920x1080:


- no HT = 3:46 mins

- with HT = 3:19


it makes sense, more cores = less time spent.

With AMD CPUS it's the other way around, HT is dramatically decreasing the performance of my tests:


- no HT = 5:47

- HT = 8:18


The CPU i use is: - AMD EPYC 7702 64 Cores @ 2.0GHz Base, 3.3GHz Turbo With the help of my company's lab technicians we optimized some setting in the BIOS, but nothing changed (here below the setting i used).

- CPU Common Options
- Performance
- CCD/Core/Thread Enablement > Accept > SMT Control = Disable
- DF Common Options
- Scrubber
- DRAM scrub time = disabled
- Memory Addressing
- NUMA nodes per socket = NPS2
- Memory interleaving = Auto
- ACPI SRAT L3 Cache as NUMA Domain = Enabled
- NBIO Common Options
- SMU Common Options
- Determinism Control = Manual
- Determinism Slider = Power
- cTDP Control = Manual
- cTDP = 240
- Package Power Limit Control = Manual
- Package Power Limit = 240


Please refer to the following result tables as an example




This issue is heavily impacting my work and it's driving me mad. I cannot figure out what the problem could be. Can you please give some support? Please let me know if you need more informations about the system or something else.