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Gaining a few fps with a Ryzen in Squad?

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Hi.

 

I found something interesting messing with the threads affinity with my 8 core Ryzen. Deactivating most of the core lead to a small increase of FPS.

 

1/ Go to the shooting range, wait 30 sec for the textures to load and fps to stabilize, note the fps.

2/ Alt-tab, open the task manager, details, right click on Squad, set affinity. If you have an 8 core, deselect everything but the core 9, 11, 13, 15. Come back to the game

3/ Come back to the game, look at your fps. If your cpu react like mine, you should gain a couple of FPS.

 

Now, it's complicated to assess how much fps you're going to gain in multiplayer game. If you have a Ryzen, could you test and tell me if you see something? (don't forget to avoid gpu bottleneck)


-Why one out of two?

To mitigate the negative effects of SMT. SMT can cause a small loss of performance in some games. Can't hurt.

 

-But why not using all the core and have something like 0, 2, 4, 6, 8, 10, 12, 14?

Ryzen it not made of 8 core with 16mb of L3, but 2 groups of 4 core (called CCX) with 8mb of L3 each. Each CCX is connected to a "data fabric", a sort of bus managing a lot of stuff at the same time. That bus have a small bandwidth, we're talking of 38 to 60go/s depending of your DDR speed. It's small, but it do not seems to be a bottleneck is most case... Most.

 

In some apps, it's possible to have a loss of performance when said app is using both ccx (not at 100%, even a very small load is enough). It's not clear yet, but the performance loss is related to the way CCX access L3 and / or threads moving from one ccx to the other, causing a noticeable increase of L3 access latency. I can't explain how or why, my knowledge is quite limited on that matter and even specialized hardware testers struggle to understand exactly how it work. Somehow in squad, there is a small gain of performance when you limit the game to one CCX.

 

I tested with SMT off and on, and i see a small gain of FPS in both case by using one ccx (squad don't even use . Not big, but it's free.

Note : the cpu is overclocked and the frequency is stable no matter the number of core used, the gain can't be caused by some kind of frequency boost.

 

If you got a Ryzen, can you test?

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ive been told amd will get a fix in the next few months so weather its ryzen or fx fx wont run 60 fps solid ryzen will 4 some reason amd on ue4 for squad parks cores i think its a c++ code problem

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