DCS Multithreading F.A.Q

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DCS Multithreading F.A.Q

Users who want to test the new multithreading version of DCS can do so by following the steps described below. Multithreading contains some known issues, but we will gladly receive reports. Please make reports as full and clear as possible that are reproducible. Also, please send crash information using the automatic send-crash tool, if possible. 

Launching Multithreading DCS
For the standalone version from our eShop DCS:

You can find the new folder "bin-mt" in your DCS / DCS Open Beta main root folder where you have installed DCS. i.e. "D:\Eagle Dynamics\DCS World\". 

To launch the multithreading version, navigate to the "bin-mt" folder and launch DCS.exe from it. i.e. "D:\Eagle Dynamics\DCS World\bin-mt\DCS.exe". 

For your convenience, you may want to create a shortcut for "D:\Eagle Dynamics\DCS World\bin-mt\DCS.exe" on your desktop. 

Be advised that the DCS launch shortcut that is automatically created on your desktop after DCS installation will launch the DCS updater from i.e. "D:\Eagle Dynamics\DCS World\bin\DCS_updater.exe". You may have gotten used to the process where you launch DCS and it checks for available updates before launching the game. If you make a shortcut for the multithreading version (i.e. "D:\Eagle Dynamics\DCS World\bin-mt\DCS.exe") then this shortcut will launch DCS, and it will not check for updates before launching the game.

For STEAM users:
Use the Play MT Preview in launch options. To do so, right click on DCS World Steam Edition in Steam and select PLAY; you should see the below pop-up.

What is multithreading (MT)?

MT is a programming technique that allows multiple threads to exist within the context of a single process. A thread is an independent path of execution within a program, and MT allows a program to perform multiple tasks concurrently, improving its performance and responsiveness. However, MT also introduces some complexities, such as thread synchronization and resource sharing, which must be carefully managed to avoid issues such as race conditions and deadlocks.

 Why am I seeing no to little performance gain?
There are several reasons that could account for this.

• One of the most common reasons for lower-than-expected performance gains is being GPU limited. Whereas MT can greatly improve CPU efficiency and resulting performance, most of the graphical rendering elements are still reliant on the graphics card. To check this, play a mission and press Right Control + Pause at the same time to display your performance Frame Per Second (FPS) and rendering information. If it indicated GPU BOUND, your graphics card is holding back the maximum possible frame rate that the CPU can provide.
• MT is most effective in large missions with many units. In small missions with a limited number of units, CPU calculations are not a gating performance limit. As such, you may not see much of an MT performance gain in small missions.
• Older CPUs will not benefit as much from MT as more modern CPUs with a greater number of cores/threads.
• Please be sure that you are using the current Open Beta and that you are using the DCS.exe from the Eagle Dynamics\DCS World OpenBeta\bin-mt\ folder if using the standalone version.
• Controls HOG PLUG is enabled. Please ensure that that HOT PLUG is disabled from OPTION / CONTROLS tab.
• You may not have appropriate BIOS setting for your CPU. If you have 32 or less cores, please ensure that HT/SMT is enabled. If you 33 or more cores, please disable this.
• If you have Vsync enabled in OPTIONS/SYSTM, uncheck the box

Are there any known issues that I should be aware of?
As an initial test version, yes.

• NS430 inoperable. Not in 2D neither 3D
• Sporadic stuttering in 2D and VR
• Ka-50: IT-23 display is colored.
• Supercarrier: there is no picture on LSO displays
• Display issues with a limited set of VR devices
• Dedicated server doesn't start automatically first time after update, hoster have to launch server manually by clicking on “start” button for mission or server itself in web GUI
• Motion Blur causes blue/black 'fog' (in single-thread only)
• Invisible player aircraft sometimes
• Cockpit tooltips
• AH-64D Instant action Persian Gulf - animator.dll crash
• If you notice other problems that you'd like to report, please visit: Multi-Threading Bug Reports (Temp) - ED Forums (dcs.world)

Why is MT currently optional?
As MT is a complex addition to DCS, we have made it optional for initial public testing. Once fully tested and working well, it will be enabled by default.

 

 How long will MT be in preview?
It depends on public test results and feedback; we will keep you all informed as things develop.

 

What is the maximum number of threads the game can utilize?
About half of P-cores are dedicated for the graphics needs. Currently the rendering pool scales up to 16 threads on P-cores (1 core = 2 threads). The other P-cores are used by the main logic thread, sound engine threads, and the auxiliary thread pool that occupy all available space. E-cores are used only by the resources streaming pool that has no limits (1 core = 1 thread).

Will VR and flatscreen have an equal performance improvement?
MT is agnostic between a 2D monitor and VR. Both will see the same proportion of improvement. Note that VR is in general more demanding so you will see lower FPS than flatscreen performance given the higher rendering overhead.

Will performance be improved for people currently bottlenecked by their GPU?
MT may not help with performance if you have a GPU bottleneck. This is because the GPU is responsible for rendering and processing graphics, and it operates independently of the CPU. So MT may not directly improve GPU performance, but it can help to improve overall application performance by offloading non-GPU related tasks to separate CPU threads.

Are there any downsides to MT if I have a CPU with few cores (Like an old quad core)?
While MT can improve performance on a CPU with multiple cores, it may not provide significant benefits on a CPU with few cores. In fact, it could even lead to decreased performance in some cases.

Will the dedicated server also be multithreading?
Currently, the dedicated server is ST. MT dedicated server should behave exactly like ST one including performance because the game logic is still running on a single thread. If you have issues with performance or anything else, please make detailed reports for us to review.

Will I be able to play on MT servers/large missions that I couldn't before?
You should see improvement in larger missions, but mission designers should still consider unit count in any mission they create. Overloading a multiplayer mission with units will result in loss of performance.

Will MT and Single Thread (ST) be updated separately or updated at the same time?
You can update DCS in the usual way.

Can MT and ST clients join the same server?
Yes, MT and ST users can play on the same server.

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

Can I expect more bugs with MT, and can they be reported the same way or do I need to do separate reports for MT and ST?
MT is a very complex addition to DCS, we have done a lot of testing but you may see issues we have missed. If you do, please report them on the forum bugs section. When reporting issues, please make it clear that you are using multithreading by either by adding “MT” to the title or in the topic itself.

 

I have not seen any improvement what can I do?
If you are not seeing any improvement in performance, please make a forum post with your dcs.log dxdiag and a track replay example in the performance issues forum section.

 

How can I launch VR in MT? 
Same way you do now but using the bin-mt/ dcs.exe with the added launch parameters. ( example "C:\DCS\bin-mt\DCS.exe" --force_enable_VR )
Steam users will have a MT VR option in the launch pop up. Or try starting in 2D and enabling VR in the DCS VR tab, then restarting DCS.

Experiencing a crash on first launch of MT DCS?

If anyone has an early crash when starting MT DCS and sees almost empty dcs.log file with/without the stack, it would be great to get additional CPU information from such user.

1. add mt.lua to Saved Games\DCS\Config\
mt.lua
2. launch DCS
3. provide Saved Games\DCS\Logs\dcs.log attached to forum post
4. remove mt.lua