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IckyATLAS

Hyperthreading - Use It

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I have an 9900K cpu wich is an octocore. With HT on this makes it for 16 thread.

IL2 is known for being a CPU bound software and using not much of the cores.

So if I take HT off, then all threads are hardware cores, and as little number of cores get used, better then have a physical core per thread and this would maximize the performance.

I tested and the result seems counter intuitive but performance dropped. Loading the game took 50% time more. During the running of the game it was slightly less performant.

Conclusion if you have HT set it to On.

 

Now comes another question. If we have 16 hardware (32 thread) cores how will things go? Bad because the clock is down per thread in those multicore processors. The 9900 KS pegged at 5GHz all cores in stock format (no additional overclocking) is still probably the most powerful solution there is even against the latest top AMD CPUs.

 

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Posted (edited)

I so far have found no benefit on my end with HT on and IL-2 - or any game I currently have.

Nothing scientific just my personal observation which is what matters to me anyways.

The benefit for me keeping it off is little lower core temps.

Edited by dburne

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Without HT on ,DRR2 has instability problems (frequent freezes) .

No statistics significant  performance gain in Il2 with HT off.

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I also found little difference between frame rates in IL-2 with HT on or off.  I'm inclined to disable it since nothing I do other than bench marking seems to benefit from it.

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The performance improvemment with HT OFF in games is an Intel only problem. I had a Ryzen 5 3600x for about a month and since end of December i have  3950x and there's zero advantage to be gained by disabling multithreading.

 On the 3950x i get a slight boost in performance if i use Ryzen master in"Game Mode". This mode disables half of the CPU in order to allow higher clocks and power on the fastest CCX turning the 16 core/32 thread CPU into a 8core/16 core CPU that it's allowed to boost at higher clocks. Runing the cores in singlethread mode, on AMD will give you no performance boost. AMD's multithreading is a bit more efficiently implemented.

 I did try it, running the 3950x in 16 core/16 threads and even 8core/8threads mode and i lost performance in both cases.

But in my case, even using the "Gaming Mode(8c/16th)" didn't give me enough performance boost to be worth running the CPU at 8/16. The graphics card is my bottleneck, so it doesn't matter in the end. 

 For everything outside gaming my pc is a lot faster in 16/32 than 8/16.

So i run it overclocked with all cores and threads banging away.

The hame engine is too old. I don't think i've seen it use more than six cores and runs a lot on a single core. 

It can't really use multithreading efficiently, so it's all about boost clock.

The game can't really  tell the difference between R5 3600x and R9 3950x.

 

You can see my results with both R53600x and R93950x in Chili's benchmark:

https://docs.google.com/spreadsheets/d/1gJmnz_nVxI6_dG_UYNCCpZVK2-f8NBy-y1gia77Hu_k/edit?usp=sharing

 

 

 

 

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Have had an i9-9900k since September and it's been overclocked stable on all cores to 5 Ghz right from the start with HT turned off. No issues and I don't think I could get the same overclock with HT turned on. So I think I'll stick with the overclock and not worry about HT.

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I recently re-enabled HT on my 8086K. Same speed, 5.0ghz, and I can't really tell a difference. I thought I was getting stuttering with just the 6 cores active and I sort of wonder what other junk Windows is running, so I figured I'd go back to 12 threads for a while and see. Inconclusive so far.

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Posted (edited)

Consider that drivers are written for the majority and the majority leave hyper-threading enabled thus it's likely optimizations are written in regardless of if you see the difference or not. Even if the game only uses physical cores windows and background applications may utilize hyper-threading optimizations and free up more resources for the game. If your only goal is single threaded performance, then yes, disabling HT for a higher overall clock would be the correct route to go, but since the majority of computing favors the ability to handle more threads rather than less, it's highly unlikely the meager gains you would see in single threaded performance will be worthwhile. I see how it's logical to think since the game relies on single thread performance so it must be better off, but unlike a console your PC is running far more processes then just the game. If you really want to geek out you can start setting background processes affinity to run on nodes the game doesn't utilize. 

 

Check out this playlist; later in the series he goes into affinity and latency 

 

 

Edited by driftaholic

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