Investigating Performance of Multi-Threading on Zen 3 and AMD Ryzen 5000
by Dr. Ian Cutress on December 3, 2020 10:00 AM EST- Posted in
- CPUs
- AMD
- Zen 3
- X570
- Ryzen 5000
- Ryzen 9 5950X
- SMT
- Multi-Threading
Gaming Performance (Discrete GPU)
For our gaming tests, we are using our AMD Ryzen 9 5950X paired with an NVIDIA RTX 2080 Ti graphics card. Our standard test suite consists of 12 titles, tested at four configurations:
- Stage 1: Actual Gaming (1080p Maximum Quality, or equivalent)
- Stage 2: All About Pixels (‘4K Minimum’ Quality)
- Stage 3: Medium Low (‘1440p Minimum’)
- Stage 4: Lowest Lows (720p Minimum or lower)
The final three settings are a set of CPU-limited gaming, and help find the limit of where we move from CPU limited to GPU limited. Some users baulk at this testing finding it irrelevant, however these configurations have been widely requested over the years. The contraire to this testing is the first setting, at 1080p Maximum: this being requested given that 1080p is the most popular gaming resolution, and Maximum Quality because this graphics card should be able to handle almost everything at that resolution at very playable framerates.
All the details for our gaming tests can be found in our #CPUOverload article.
| Stage 1: Actual Gaming AMD Ryzen 9 5950X, SMT On vs SMT Off |
|||
| AnandTech | Settings | Average FPS |
95th Percentile |
| Chernobylite | 1080p Max | 100% | - |
| Civilization 6 | 1080p Max | 103% | - |
| Deus Ex: MD | 1080p Max | 99% | 100% |
| Final Fantasy 14 | 1080p Max | 102% | - |
| Final Fantasy 15 | 8K Standard | 100% | 99% |
| World of Tanks | 1080p Max | 100% | 102% |
| World of Tanks | 4K Max | 103% | 102% |
| Borderlands 3 | 1080p Max | 101% | 103% |
| F1 2019 | 1080p Ultra | 103% | 106% |
| Far Cry 5 | 1080p Ultra | 104% | 104% |
| GTA V | 1080p Max | 99% | 100% |
| RDR 2 | 1080p Max | 100% | 100% |
| Strange Brigate | 1080p Ultra | 101% | 101% |
In real-world gaming situations, there’s very little to pick between having SMT enabled or disabled. Almost universally it is either beneficial or a smidgen better to have it enabled, with F1 2019, Civilization 6, and Far Cry 5 seemingly the best recipients. I’ve also added in the Stage 3 result from World of Tanks, just because that benchmark doesn’t really have a proper settings menu.
| Stage 2: All About Pixels AMD Ryzen 9 5950X, SMT On vs SMT Off |
|||
| AnandTech | Settings | Average FPS |
95th Percentile |
| Chernobylite | 4K Low | 99% | - |
| Civilization 6 | 4K Min | 105% | - |
| Deus Ex: MD | 4K Min | 98% | 100% |
| Final Fantasy 14 | 4K Min | 102% | - |
| Final Fantasy 15 | 4K Standard | 100% | 100% |
| Borderlands 3 | 4K Very Low | 101% | 104% |
| F1 2019 | 4K Ultra Low | 100% | 100% |
| Far Cry 5 | 4K Low | 101% | 100% |
| GTA V | 4K Low | 100% | 101% |
| RDR 2 | 8K Min | 100% | 100% |
| Strange Brigate | 4K Low | 100% | 100% |
With our high resolution settings with minimal quality, there is only one outlier in Civilization 6 on the average frame rates, which seem to be a bit higher when SMT is enabled.
| Stage 3: Medium Low AMD Ryzen 9 5950X, SMT On vs SMT Off |
|||
| AnandTech | Settings | Average FPS |
95th Percentile |
| Chernobylite | 1440p Low | 100% | - |
| Civilization 6 | 1440p Min | 105% | - |
| Deus Ex: MD | 1440p Min | 97% | 96% |
| Final Fantasy 14 | 1440p Min | 102% | - |
| Final Fantasy 15 | 1080p Standard | 101% | 105% |
| World of Tanks | 1080p Standard | 101% | 101% |
| Borderlands 3 | 1440p Very Low | 103% | 105% |
| F1 2019 | 1440p Ultra Low | 99% | 99% |
| Far Cry 5 | 1440p Low | 99% | 99% |
| GTA V | 1440p Low | 100% | 99% |
| RDR 2 | 1440p Low | 100% | 100% |
| Strange Brigate | 1440p Low | 100% | 100% |
At the more medium settings, we’re starting to see some more variation (Borderlands gets a few percent from SMT). We’re starting to see Deus Ex:MD drop off a bit with SMT enabled.
| Stage 4: Lowest Lows AMD Ryzen 9 5950X, SMT On vs SMT Off |
|||
| AnandTech | Settings | Average FPS |
95th Percentile |
| Chernobylite | 360p Low | 106% | - |
| Civilization 6 | 480p Min | 102% | - |
| Deus Ex: MD | 600p Min | 91% | 91% |
| Final Fantasy 14 | 768p Min | 102% | - |
| Final Fantasy 15 | 720p Standard | 99% | 102% |
| World of Tanks | 768p Min | 101% | 100% |
| Borderlands 3 | 360p Very Low | 108% | 110% |
| F1 2019 | 768p Ultra Low | 102% | 105% |
| Far Cry 5 | 720p Low | 100% | 101% |
| GTA V | 720p Low | 99% | 98% |
| RDR 2 | 384p Low | 100% | 103% |
| Strange Brigate | 720p Low | 95% | 95% |
This is perhaps our most varied set of results, with Deus Ex:MD showing an almost 10% drop with SMT enabled. DEMD is usually considered a CPU title, but so is Chernobylite, which sees a 6% gain. Borderlands is +8-10% with SMT enabled, which is more of a modern game. However, I doubt anyone is playing at these resolutions.
Overall Gaming Performance
If we take full averages from all the data points, then we’re seeing a rough +1% gain in performance in the more complex scenarios across the board.
| Resolution Average Comparison AMD Ryzen 9 5950X, SMT On vs SMT Off |
||||
| AnandTech | Setting | aka | Average FPS |
95th Percentile |
| Stage 1 | 1080p Max | Actual Gaming | 101% | 101% |
| Stage 2 | 4K+ Min | All About Pixels | 101% | 101% |
| Stage 3 | 1440p Min | Medium Lows | 101% | 101% |
| Stage 4 | < 768p Min | Lowest Lows | 100% | 101% |
In reality, any loss or gain is highly dependent on the title in question, and can swing from one side of the line to the other. It’s clear that Deus Ex prefers SMT off, and F1 2019 or Borderlands prefers SMT on, but we are talking fine margins here.
Facebook
Twitter
RSS
126 Comments
View All Comments
dotjaz - Thursday, December 3, 2020 - link
Do you understand what "S(imultaneous)" in SMT means? Barrel processors are by definition NOT simultaneous. They switch between threads.quadibloc - Friday, December 4, 2020 - link
That all depends. There could be a unit that switches between threads to dispatch instructions into the pipeline, but instructions from all the threads are simultaneously working on calculations in the pipeline. I'd call that a way to implement SMT.Elstar - Friday, December 4, 2020 - link
Guys, I've got bad news for you. The difference between a barrel processor ("temporal multithreading") and SMT is all about the backend, not the frontend. I.e. whether the processor is superscalar or not. Otherwise there is no difference. They duplicate hardware resources and switch between them. And the frontend (a.k.a. the decoder) switches temporally between hardware threads. There are NOT multiple frontends/decoders simultaneously feeding one backend pipeline.Elstar - Friday, December 4, 2020 - link
For example the "SMT4" Intel Xeon Phi has a design weakness where three running threads per core get decoded as if four threads were running. (And yes, just one or two running threads per core get decoded efficiently.)dotjaz - Thursday, December 3, 2020 - link
You nailed 2 letters out of 3, gj.Luminar - Thursday, December 3, 2020 - link
Talk about being uninformed.MenhirMike - Thursday, December 3, 2020 - link
Will be interesting to see if this looks different with Quad-Channel Threadripper or Octo-Channel EPYC/TR Pro CPUs, since 16 Cores/32 Threads with 2 channels of memory doesn't seem very compute-friendly. Though it's good to see that "SMT On" is still the reasonable default it's pretty much always has been, except in very specific circumstances.schujj07 - Thursday, December 3, 2020 - link
Also would be interesting to see this on a 6c/12t or 8c/16t CPU.CityBlue - Thursday, December 3, 2020 - link
In your list of "Systems that do not use SMT" you forgot:* All x86 from Intel with CPU design vulnerabilities used in security conscious environments
MenhirMike - Thursday, December 3, 2020 - link
To be fair, "x86" and "security conscious" are already incompatible on anything newer than a Pentium 1/MMX. Spectre affects everything starting with the Pentium Pro, and newer processors have blackboxes in the form of Intel ME or AMD PSP. You can reduce the security risk by turning off some performance features (and get CPUs without Intel ME if you're the US government), but this is still just making an inherently insecure product slightly less insecure.