Hyper Threading should be off for DCS & MT(multithreading)

[YoYo]

Hi,

Do you have idea why HT should be OFF (32+ threads)? What negative symptoms would be for 32+ threads? 

Quote

Should I enable HT / SMT in my motherboard BIOS?
Currently, users with 32 threads or more should disable HT/SMT, but for everyone else we recommend enabling HT/SMT.

I never did it on my spec, where is it disabled in BIOS?

[Dragon1-1]

It seems that there's currently an issue in which DCS won't start at all if there are more than 32 threads. That's the sort of thing you get with a rough implementation of multithreading logic. No doubt they'll need to fix it before the MT branch becomes the default.

[YoYo]

Ok, known issues:

Quote

Known Issues

• Multithreading:
  • DCS won’t start on a PC with CPU with more than 32 CPU threads.

So maybe if it will be OFF, DCS will start?

1 minute ago, Dragon1-1 said:

It seems that there's currently an issue in which DCS won't start at all if there are more than 32 threads. That's the sort of thing you get with a rough implementation of multithreading logic. No doubt they'll need to fix it before the MT branch becomes the default.

Yes, I saw it too. I have i9 13900KF so I'll check firstly with my HT=on. We'll see.

Some people I know have just replaced their processors with i9 13xxx for DCS only and here's a surprise !

[AdrianL]

21 minutes ago, YoYo said:

i9 13900KF

You only have hyper threading on your P-Cores so you  have exactly 32 threads (logical processors) 

8 P-Cores, 16 E-Cores = 24 Cores  Add 8 threads to your 8 P-Cores for HyperThreading  = 32

I am running on a 13900KF with no issues so far with hyperthreading on. Getting some amazing FPS on the few instant action flights I have taken

 

Edited March 10, 2023 by AdrianL

[SkateZilla]

52 minutes ago, YoYo said:

Hi,

Do you have idea why HT should be OFF (32+ threads)? What negative symptoms would be for 32+ threads? 

I never did it on my spec, where is it disabled in BIOS?

DCS Will Crash if it's more than 32-Threads (ie ThreadRipper).

[YoYo]

21 minutes ago, AdrianL said:

You only have hyper threading on your P-Cores so you  have exactly 32 threads (logical processors) 

8 P-Cores, 16 E-Cores = 24 Cores  Add 8 threads to your 8 P-Cores for HyperThreading  = 32

I am running on a 13900KF with no issues so far with hyperthreading on. Getting some amazing FPS on the few instant action flights I have taken

 

 

Ah! Right! It was MORE than 32, not 32. Good info.

[AndyJWest]

The FAQ was changed at some point in the last few hours - it now says "Currently, users with more than 32 threads should disable HT/SMT, but for everyone else we recommend enabling HT/SMT." It would probably be wise for YoYo to note this in the first post.

[YoYo]

53 minutes ago, AndyJWest said:

The FAQ was changed at some point in the last few hours - it now says "Currently, users with more than 32 threads should disable HT/SMT, but for everyone else we recommend enabling HT/SMT." It would probably be wise for YoYo to note this in the first post.

Exactly, looks like they did mistake!

[shazam253]

Well, I am wondering if they did some tests. Often times, there is little difference between hyper threading on or off, since the number of physical cores is the same. The added overhead to split work may even lead to a slight decrease in performance.

Has anyone tested this for the MT version?

[avigdorlado]

HT splits a physical core into two logical nodes through timing and other gimmicks. Certain calculations benefit from from HT, others like HPC, don't. Even without MT, DCS runs better without HT.

[okopanja]

Do not use HT with DCS. Even with MT it results in lower and less stable FPS.

[Wiggo]

Does this mean threads of GPU or CPU? In which conditions i would like to want to use mt-dcs.exe (c:\\dcsmainfolder\mt-bin\mt-dcs.exe. What is the concrete difference, while i dont have a clue which one I want or even shoudl use. Nor what it does / should not do. It starts though, I have pretty old computer (intel i54960k, gtx 960 4gb, 20gb ddr3, ssd (SATA). I have seen text multithreading for years in boxes of pc stuff, but havent really ever desided to look what it means? Sound cool and fast though. So could somebody tell me something about this. What is it, how is it used, why is it used, and who can use it and how one knows it. And even then, what is the difference between mt-dcs.exe and dcs.exe? which one should I start, or does it do it automatically. MT-dcs.exe  does, as mentioned, start in my computer, but did not notice any difference, though dont know even where to look... ;D Thought this might be good to ask before I cry later.. 

[okopanja]

I can not be sure, but it looks like at some point things changed for me: now it work better for me with hyperthreading on.

When I posted previous message in March I did switch it on to check. Back then the FPS was very irregular and jerky with ON setting. Now it looks opposite. I think either ED did some changes and tweaks or NVIDIA/Microsoft did roll out some update that fixed it for me.

I would recommend everyone to check what is the current state and decide based on that if they enable or disable hyperthreading.

[Hiob]

20 minutes ago, Wiggo said:

Does this mean threads of GPU or CPU? In which conditions i would like to want to use mt-dcs.exe (c:\\dcsmainfolder\mt-bin\mt-dcs.exe. What is the concrete difference, while i dont have a clue which one I want or even shoudl use. Nor what it does / should not do. It starts though, I have pretty old computer (intel i54960k, gtx 960 4gb, 20gb ddr3, ssd (SATA). I have seen text multithreading for years in boxes of pc stuff, but havent really ever desided to look what it means? Sound cool and fast though. So could somebody tell me something about this. What is it, how is it used, why is it used, and who can use it and how one knows it. And even then, what is the difference between mt-dcs.exe and dcs.exe? which one should I start, or does it do it automatically. MT-dcs.exe  does, as mentioned, start in my computer, but did not notice any difference, though dont know even where to look... ;D Thought this might be good to ask before I cry later.. 

https://en.wikipedia.org/wiki/Hyper-threading

Which (ST ot MT) is better suited for your hardware, I can’t really tell. Just try and use them one after the other. ST will be gone in the foreseeable future probably, when the birth pain of MT is ironed out.

You run the ST (classic) DCS-executable from the /bin subfolder and the MT from the /MT-bin (or /bin-MT). Just make two shortcuts and use either one as you please.

[Wiggo]

5 hours ago, Hiob said:

https://en.wikipedia.org/wiki/Hyper-threading

Which (ST ot MT) is better suited for your hardware, I can’t really tell. Just try and use them one after the other. ST will be gone in the foreseeable future probably, when the birth pain of MT is ironed out.

You run the ST (classic) DCS-executable from the /bin subfolder and the MT from the /MT-bin (or /bin-MT). Just make two shortcuts and use either one as you please.

Atleast MT-DCS seem to use cpu much more, where it has been confusingly low before. I can also verify huge change in cpu temp. Now the fans are on level that they are in many other games, which i think is good sign in this case? (not sure..) OR ofc that doesnt tell <profanity> just like that, but AT LEAST cpu is doing something much more  My old i5 4960K 6mb OC unlocked crazy old workhorse likes to calculate stuff!  No seriously, there really seems to be noticable difference, at least when looking with windows tools, how it uses cpu vs non mt-version. Dunno if thats ment to. It has not crashed eather, as normal version of 2.9 did few times yesterday when playing campaign. Dunno if it has been just luck, time will show. Seems that mt version runs better for now in my computer. Nice. I really dont know anything about this stuff, though know "something" about pc´s as worked in pc industry, BUT it was in 90´s ;D No Multi anything back then. Multimedia maximus.

[Hiob]

1 hour ago, Wiggo said:

Atleast MT-DCS seem to use cpu much more, where it has been confusingly low before. I can also verify huge change in cpu temp. Now the fans are on level that they are in many other games, which i think is good sign in this case? (not sure..) OR ofc that doesnt tell <profanity> just like that, but AT LEAST cpu is doing something much more  My old i5 4960K 6mb OC unlocked crazy old workhorse likes to calculate stuff!  No seriously, there really seems to be noticable difference, at least when looking with windows tools, how it uses cpu vs non mt-version. Dunno if thats ment to. It has not crashed eather, as normal version of 2.9 did few times yesterday when playing campaign. Dunno if it has been just luck, time will show. Seems that mt version runs better for now in my computer. Nice. I really dont know anything about this stuff, though know "something" about pc´s as worked in pc industry, BUT it was in 90´s ;D No Multi anything back then. Multimedia maximus.

Apart from changes due to temperature headroom, two cores will use roughly double the energy of one, so more heat does in this case really mean more stuff is computed in the same time.

ST is a dying horse anyway, so I assume that especially the new candy is mainly (or only) optimized for the Multithread environment.

Good when it gives a new breath of life to a rather senior system….

[Wiggo]

15 minutes ago, Hiob said:

Apart from changes due to temperature headroom, two cores will use roughly double the energy of one, so more heat does in this case really mean more stuff is computed in the same time.

ST is a dying horse anyway, so I assume that especially the new candy is mainly (or only) optimized for the Multithread environment.

Good when it gives a new breath of life to a rather senior system….

WOOOW! I changed visibility extreme->high and clouds form ultra->high, as before i had like +/- 2-3fps with those. Now syria map, msaa 4x, sharpened 0,6 no dlss anything 44 fps on the ground. Thats +1/3 (~+30%) fps for me  Those correlate now (at least for me) way much more what comes to fps. Ofc cant see so far, but this fps lvl was pretty much with "no filters + in the flight high, no other planes around" - stuff before, with my computer. Clearly something has also done right in the patch, was it MT or not. (did not try yet does those settings corralete as much with ST , in 2.9. Ofc it can be also the patch only, but i totally will keep running it like this and now i PLAY Have  thumbled with settings since yesterday, more or less. Restless soul and so on..  ;D

Edited October 21, 2023 by Wiggo

[motoadve]

AMD 7800X3D I turned SMT off, I definitely get smoother gameplay and higher fps in single player, its confirmed it improved the performance.

Multiplayer I am not so sure, performance is not so good, could it be possible it only helps in single player and not in MP?

[Hiob]

9 hours ago, motoadve said:

AMD 7800X3D I turned SMT off, I definitely get smoother gameplay and higher fps in single player, its confirmed it improved the performance.

Multiplayer I am not so sure, performance is not so good, could it be possible it only helps in single player and not in MP?

Eight physical cores are plenty. I have also turned off SMT a long time ago. It didn’t change the performance for me but got rid off a lot of microstuttering and frametime spikes. I think it is the crappy windows scheduler that doesn’t (or didn’t) play well with AMD CPUs. If that is still the state of affairs after the recent „9000“ fix - I don’t know. But I don’t need Hyperthreading/SMT right now, so I just leave it.