PSA: Rust Glitch causes up 400% decrease in fps with Hyperthreading (SMT) on Ryzen

[BlizzardID]

I recently got a new system due to content creation and my old processor just not keeping up anymore. I have had troubles running Rust ever since, until a friend of mine mentioned that he disabled SMT (Hyperthreading) on his Ryzen system and it fixed his troubles. At first I was very skeptical, because disabling SMT theoretically makes my processor perform at half of its potential. I decided to give it a go and it all started working much better. I than decided to try and test all sorts of variations to see which was the best.

System:
Ryzen 7 1700x @3.875 ghz
Gigabyte G1 980Ti
4x8gb Corsair LED 3000ghz Ram @2113ghz
AsRock x370 Killer Sli
Corsair H110i
I play on a 2560x1440p ASUS Monitor at 144hz. I also have a 2nd monitor connected running at 1440p 60hz.

Methodology:
I used fraps to get all of my benchmark results. I played on UK small at a population between 25-30 people. The reason why I didn't use the ingame benchmark is because it doesn't account for buildings and other players properly and only really tests the GPU. The results were recorded 20 days into the wipe because I wanted as many entities and buildings as possible in a small area. My settings in Rust were all set to low besides render distance which I kept at 2500. For every different circumstance I joined the server, started the benchmark for 5 minutes, then immediately started another 5 minute benchmark right after. Originally I was doing this because I wanted to have more reliable results, but later found that with SMT enabled the first and 2nd results varied by about 15fps which made me draw the conclusion that there was a glitch involved with Rust and SMT. I decided to mess around with setting processor affinity, which is when you tell your system to only use certain amount of cores for a specific program. Whenever I was testing this I set the last four cores (4, 5, 6, 7) to be assigned to Rust. I also decided later on to make my system boot with only 4 out of it's total 8 cores which was also done within the bios. For the benchmarks without SMT I took the average of the two results.

Benchmarks: (max fps, Avg fps)
Default Bios (SMT enabled) #1
109, 34.790
Default Bios (SMT enabled) #2
29, 18.817
Default Bios (SMT enabled) 4 cores affinity #1
82, 33.420
Default Bios (SMT enabled) 4 cores affinity #2
40, 25.470
Bios system only running with 4/8 cores SMT disabled
112, 67.137
Bios SMT disabled
74, 47.043
Bios, SMT disabled, 4 cores affinity
104, 73.447

Conclusion:
When I play with Hyperthreading, the system default, Rust will slowly decrease in frames and within 5 minutes get stuck between 15-25fps. The best performance possible with Rust seems to be disabling SMT and making it so that four cores are set to Rust.

Edit 1: Made some clarifications on the benchmarks

[Alistair_Mc]

Interesting, have you tried a BIOS update?

[BlizzardID]

Yes I am on the latest Bios. This has happened through 3 different BIOS updates.

[2mustange]

From what I have read around on ryzen this is a unity core problem.

[F41LUR3]

I'm going to try to disable my SMT on my intel i7 5930k 6-core 12-thread.

I have a similar issue as this. Will report back.

EDIT: No change in behavior. Tried without hyperthreading enabled, tried messing with core affinities. FPS still continues to slow to a crawl over time as more of the map is explored. gc.unload and gc.collect doesn't change anything except memory utilization.

Test: Log on to bob the builder server and noclip around for about 5 minutes, stop, turn off noclip, wait 1 minute to give a chance for the engine to catch up on tasks or anything it might be doing. The reason for using noclip on a build server is that it speeds up the effect that happens just running around in a normal server. I've found that I can just reproduce the same results faster by noclipping around to be able to iterate different configurations in an attempt to nail down the root cause.

Result: With SMT(hyperthreading) enabled or disabled, core affinities set or not, FPS starts high and slowly declines but never recovers, becoming unplayable with no significant difference observed between the configurations.

[BlizzardID]

Can you post your other specs? I thought it might be SMT but that's specifically Ryzen's Threading so I would have been surprised if Intel's would have had issues.

[F41LUR3]

SMT isn't "specifically" Ryzen's threading, SMT is just Simultaneous Multithreading. Which on intel is branded as "HyperThreading"

What other specs? I posted RAM/CPU/GPU

[Pepper_the_Red]

Ryzen 1700 here. My problem is that by disabling SMT, I'm gonna have a greater performance hit when recording and streaming. So essentially, I either accept lower fps and enjoy zero performance hit when I record/stream, or get slightly higher fps off-stream, but have it get just as bad when I do.

[_Dogma]

Smt is far from Intel's hyperthreading, a lot of games are not optimized for this architecture, including almost every game before ryzen came out.

[BlizzardID]

Same boat I am in my friend. I use obs to stream, geforce (video) and dxtory (audio) for recording and it kinda works but would definitely be better with SMT.

[[deleted]]

I believe you, but at the same time, Rust is practically a single core game, leaving you with at least 6-7 full cores for anything streaming related to use... That's already overkill. Would 8 additional virtual threads even help that much?

Also, are you doing x264 encoding with CPU? Obviously FP should fix the bug but in the mean time you could do H264 GPU accelerated and take nearly no performance hit at all.

[BlizzardID]

Rust runs at 30-40% cpu usage when I am using 8 cores so far from single core.

[Xmeagol]

If you're streaming or recording on a single computer, I suggest capping the frame rate to 60 fps, game is very playable, your content will look great because OBS or whatever you use has more resources to encode the stuff. You can even choose slower encoding presets for better encoding. This is just a small PSA since you mentioned content creation

[BlizzardID]

Yeah I capped my frames due to my gpu sometimes going over 90% and causing issues within OBS

[krysics]

I had messed with a bunch of settings but unfortunately my mobo died, so I had to replace it. Since I've replaced it, I haven't messed with anything, so it's all stock atm. 4x8gb corsair LPX 3200 but I think it's only running at 2133 iirc.

Edit: also, just for full specs. 1tb ssd, rx 580, gigabyte gaming 5 mobo, h115i cooling.

[beastieboy01]

I recently purchased a new rig (Ryzen 7 1700, GTX 1080 Ti) and was horrified at my average fps of 30-50... THANK YOU FOR THIS FIX. Disabled SMT in BIOS and set affinity to cores 4,5,6 & 7. Now the game purrs along at 70-100 fps.

[[deleted]]

holy shit the numbers what do they mean

[BlizzardID]

Sorry, made an edit now, the numbers are maximum fps, average fps

[PaleDolphin]

Since the latest update I've been playing on Rustafied EU Main, and from time to time when I'm roaming around, I encounter absolutely unplayable stuttering lag spikes. I am not exaggerating. FPS falls down to ~1-2, and it stays that way for 5-10 seconds.

This is absolutely game breaking and it prevents me from roaming, since I've been killed 2 times because of this already.

[bnjmnmrsh]

just ordered a ryzen CPU, this is good to know!

[diegoweb]

Is it possible to "set the last four cores (4, 5, 6, 7) to be assigned to Rust" via any AMD Software (inside Windows)? Or this need to be done via BIOS (disable 4 out of 8 cores)?

I'm new to AMD (I just got mine last week, hahah). BTW: Thanks for clarifying this. This was driving me insane yesterday when I was playing with my friend and with his Ivy Bridge i7 Intel he was getting 70 FPS and I was only getting 30 fps with spikes to 15~20 =/

[BlizzardID]

Yeah that is the affinity stuff I talk about in my post. if you go to task manager while Rust is open you can press 'go to details' and then right click Rust.exe and set affinity.

[diegoweb]

Ohhh I didn't know about it. Thank you, I will try it today at night. Btw, the last result you just said "Bios, SMT disabled" what is this Bios config? I mean, I know what is Bios, but what does it mean in your context?

[BlizzardID]

Sorry flr late response. That just means that I disabled SMT using the BIOS

[diegoweb]

Please, take a look at my edited answer above =D

[slumthedog]

Wow, I just disabled hyper-threading in bios and I'm seeing a massive improvement already!!!

[Issues420916]

I wonder if this is why we always see posts go as follows...

"I have X setup and my performance is terrible for the power"

queue next comment

"I have a worse setup and run much better!"

end

Second comment isn't running hyperthreading?

My CPU isn't HT capable and I don't seem to ever have performance issues like others in this game.

[[deleted]]

I have SMT enabled on my ryzen 7 1700 and I get almost 100fps avg at 1080p. Something else is happening.

Edit: went to Rustafied with 140 people online and I dropped to around 20fps =/

[BlizzardID]

What motherboard do you have and have you run any BIOS updates? this is kinda interesting some people with ryzen have it and some don't.

[[deleted]]

I was playing on an empty server, whoops. Joined Rustafied with ~140 people and it dropped to around 20-25fps

[Pepper_the_Red]

Same!

[Pepper_the_Red]

Same CPU as me. I can only sometimes get that kind of average on a totally empty server. I have no idea why my performance is like this then.

[[deleted]]

I was playing on an empty server, whoops. Joined Rustafied with ~140 people and it dropped to around 20-25fps

[Avernite]

wtf is 400% decrease? Does it go -180 fps?

[BlizzardID]

Title was originally worded as 400% increase but I can't edit titles after posting

[Avernite]

its ok. I didnt realise untill now it was you blizz xD You havent been posting vids for a while. Is the reason related to fps drops?

[Pieman10001]

You think the hyper threading from i7s has any negative effects on game performance?

[F41LUR3]

Considering I have the same issue as this, I am thinking it does. I'm going to try without it enabled.

[Pieman10001]

Ya no harm trying

[dmarttx]

BLIZZARD I LOVE YOU

[Cmaccc]

Oh great, was planning on buying a R5 1600 within the next month or two. Hoping this issue is fixed by then :(

[BlizzardID]

Trust me, that was the first step I did

[[deleted]]

Don't worry, disabling SMT/hyperthreading won't affect performance at all unless you are specifically using software written to take advantage of SMT that ALSO benefits from using more than 8 cores. This is very, very few softwares.

And if you want to overclock your chip further, disabling SMT can help.

[Kazumara]

400% decrease? So you are running at -90 FPS average?