YEAH ! confirmed i gained some FPS by setting my game to only 2 cores, and the server to the other 2 cores ! it works! huge thanks !
now i'm working on a different level of optimization...i'm tryint to totally spawn and de-spawn fixed units like 0.50cal turrets, fixed AAA, mines and even squads with guard roles (that stay always in the same place to defend) ...based on variable distance (like mines should spawn at 100 meters from them)!
will let you know my progress in next days!
thanks ! bye !

Out of interest @DLEGION how much FPS did you gain with the headless client?

heey hi!

well...here is the setup (to get the whole picture):
i run a dedicated server on my own PC. i run my game too from same PC.
a friend run headless and his own game from his PC.
i got aroun 10 FPS boost with his headless,
while if i run headless from my own PC it go worse than with no headless at all ! (around -5 FPS)

Hi folks,

would really like to have some more information on that issue. If I have 4 physical cores (core i5 4690K) and want to run dedi, headless client and my client instance on the same PC, who do I best distribute the cores when assigning them in task manager?

I see core 1,2,3,4, no core 0 here?

And @SavageCDN: if I assign core 1+2 for server, 3+4 for HC, what do you mean with "player client the rest"? I tell task manager to use resources from all cores for this process or what? Sorry for being a bit thick, but I can't see how that would work if all 4 cores are already assigned to server and HC.

Eh...i have an i5 4440, four cores. For me the best result is to run a dedicated server on core 1,2 and client on 3,4 and no headless at all. Usually a friend of mine take the headless and in that case the server goes faster !

Thanks for making things clear @ both of you!

Now I have to wait for the 1.60 compatible ALiVE update before I can try how it works I guess...

First of all thank you everybody in the ALiVE's community, this is one of the best mods around.

I did not known about the server / client CPU load split before, it's a gamechanger for me in SP.
I've made a stress test similar to DLEGION's one, maybe a little more "intense" with NATO and CSAT actively figthing each other in invasion mode. On a i7 3770K (8 cores) & 16Gb of RAM, the cpu load split (4 on server side & 4 player/client side) it's a day/night boost, very impressive!
The simple server configuration is a complete stress test success. I've tried to go further with an headless client on the same CPU, as suggested by SavageCDN: server on cores 0,1; HC on cores 2,3; client on the rest. Unfortunately (and maybe it's because this stress test is way too demanding) results went wrong: server cores 0,1 were on a 100% constant load, while HC cores 2,3 were around 70/90% load. The game ran not so smoothly as before, a consistent 20/30 fps drop compared to the simple server (no HC).

Maybe is it something wrong on the configuration I've made? I've placed a playable Game Logic unit (Headless Client) and set the AI Distribution switch of the ALiVE Required module to Headless. CPU load and RAM usage of the server and HC seem to say the thing is working... I've even tried switching off the HC while ingame, redistributing the load, and performance boosts back as the single server test.

Is it possible (for this stress test) that 4 cores are enough for a simple server and not for a server + HC split? Or did I simply messed up something? :)

Thank you!

Just use launcher if your doing it all from same PC.

1. Load Arma as normal ( with your required mods )

ALT+TAB out to desktop.

Open "Task Manager" and select "Details". Find "arma3.exe" and right click. Select "Set Priority" and change to "High". Next same right click "arma3.exe" and change "Set Affinity" , change it to the number of cores you wish to use. This all depends on how many cores you have for your CPU and if you use Hyperthreading.

Hyperthreading doubles the core list so CPU core 1 would be 1&2, Core 2 would be 2&3 etc

2. Select Parameters, Advanced Tab, Host from arma 3 launcher. You need to select....

Server.... Just tick

Server port.... default 2302 or what ever you use.

CFG... This is your Arma3server_basic.cfg ( direct it to folder with this in )

Config... This is your Arma3Server.cfg ( direct it to folder with this in )

Dedicated Server... 127.0.0.1

Load Mission to Memory

Once that is done click Play.

ALT+TAB out to desktop.

A little arma 3 command window should appear.

Back to the task manager and you should have 2 arma3.exe files in the details list.

If your not sure which one is the server arma3.exe, hover over set priority and if it's "High", then thats the Client (The default we just done ).
Select "Set Priority" and change to "Above Normal"
Next same right click "arma3.exe" and change "Set Affinity" , change it to the number of cores you wish to use.

3. Now we need to untick all the options in Parameters/Advanced tab/Host in arma 3 launcher.

If you plan to use Headless Client.. Select Launch Headless Client in Host list.

Now open Client above Host and we need to tick...

Server Address... 127.0.0.1

Server Port... 2302 or whatever you use

Server Password... This is the first password you use not your admin password.

Click play.

ALT+TAB out to desktop.

Another arma 3 command window will appear behind the first so move it to see both.

Do same with task manger ( you should have 3 arma3.exe ) and and just set affinity this time to what ever cpu cores you have left. I only use 1 core per headless client. Remeber just right click and mouse over set priority to see if it's set to High or above normal. If it is, then that's the first 2 the client and the server.

I do

Client=Priority "High"
Server=Priority "Above Normal"
Headless Priority "Client=Normal"

You must make sure you have added a Headless client in your mission and make it playable. I use the name "HC" for first Headless Client added in Eden.

Also a add....

//HEADLESS CLIENT
localClient[]={127.0.0.1};
headlessClients[]={"127.0.0.1", ...};

to your arma3server.cfg.

Also change Alive required module from Server to Headless client

Now click arma 3 in taskbar to get back to arma main screen and click multiplayer and servers.

You should now see your server in the list and be able to play from your server and have a headless client if added to mission and server.cfg file.