Why is Vulkan harder to run than OGL and DX?

prime2515102

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So I was running Doom (2016) with Vulkan and it locked my computer up completely. I tried again and it crashed to the desktop. I switched to OpenGL 4.5 and it ran fine. hmmm...

I went and downloaded GFXBench (the first Vulkan benchmark that came up in my search) and it also locked up just as the first test was ending, and it gave me a bluescreen.

This surely isn't from my GPU overclock, I thought, because I can run everything else (including FurMark's stress test) all day long without a hitch.

I decided to try setting the GPU and MEM clocks to default and everything ran fine. I then upped the clocks again just slightly under the previous OC and everything is still fine.

So what is it about Vulkan that makes it harder to run than OGL4.5 and DX 9+? Or is this an nVidia driver/hardware issue (I'm currently running a GTX 1080 8GB)?
 
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travm

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Vulkan is based on mantle which was originally an AMD only API. The 1080 may not even properly support Vulkan, it is relatively new.
Just thoughts
 

deruberhanyok

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Vulkan is a low level API, like D3D12. Performance can be noticeably higher with good drivers.

Possible your card is just using more power and running hotter under Vulkan - with most cards you’ll see a performance increase in games that support it vs ogl/ d3d11. Similar to when d3d12 is available as an option.

I’m not sure how optimized nvidia bothered to make the Vulkan drivers for Pascal though. did you notice if doom Vulkan runs better than ogl on your card (it should)?
 

prime2515102

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Vulkan is based on mantle which was originally an AMD only API. The 1080 may not even properly support Vulkan, it is relatively new.
Just thoughts
I didn't realize that, I thought it was just a marketing name for a newer version of OpenGL.

After you mentioned that I read on AMD's site, "...to deliver meaningful features, performance, and image quality and expose GPU hardware features that wouldn’t ordinarily be accessible through OpenGL." This would explain it I guess; maybe part of the hardware it's accessing that OGL can't just can't handle the overclock.
Vulkan is a low level API, like D3D12. Performance can be noticeably higher with good drivers.

Possible your card is just using more power and running hotter under Vulkan - with most cards you’ll see a performance increase in games that support it vs ogl/ d3d11. Similar to when d3d12 is available as an option.

I’m not sure how optimized nvidia bothered to make the Vulkan drivers for Pascal though. did you notice if doom Vulkan runs better than ogl on your card (it should)?
I didn't even check but I'll go do that and post back.
 

cybereality

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Vulkan isn't any harder to run than GL or DX. However GL has been around for a long time and battle-tested, as well as DirectX which runs most games on Windows.

On the other hand, Vulkan is relatively new and a limited number of games are using it, so it's possible it is not as tested as the other options.

Additionally, it's a totally different software API, and may interact with overclocking differently. That is why it is always good to test a wide range of games when you OC your system. What works well in one game with one API could potentially crash in another. This is normal.

Finally, while Vulkan was based on Mantle, it was heavily modified by Khronos to work cross-platform, and should have no problem with newer Nvidia cards as well as AMD. However, driver bugs are always possible, especially since the API is newer and not the most popular, you could run into issues.
 

prime2515102

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Ok, I just checked the numbers and no wonder!

This is very unscientific because it was just a quick run with a FPS-o-meter in the corner (I didn't use Fraps or anything).

I'm on the level where you jump down onto a train and it moves forward into a relatively small area with lots of monsters (I think it's just before the end of the game, not sure). When loading the level it starts off with you on the train.

With OGL the framerate started at about 167 once the train started moving, and was at about 105 when it stopped inside the room with all the monsters.

With Vulkan it started at about 201 and was at 177 when the train stopped.

I went back and forth running each twice with roughly the same result.

This would definitely explain it. There's obviously a lot more of the GPU getting beaten on here. lol

Edit: I have to say, this seems pretty unbelievable. Why aren't all games Vulkan? That's like a $500 upgrade in performance for free. Maybe I better run fraps or something...
 
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KATEKATEKATE

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Re: why not Vulkan for all games
I've read that ID did an especially determined job of optimizing Doom for Vulkan, I'm not sure that those kind of gainz are seen across the board with Vulkan titles. I think it's kind of like when Ashes of the Singularity came out and folks saw huge boosts going from the DX11 path to DX12 path on AMD GPUs and proclaimed it an Epic Win, only for improvements to be more modest or nonexistent in other subsequent DX12 games.

TL;DR Doom 2016 is just Hella Optimized
 

FlawleZ

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Well, seems FRAPS doesn't work with Vulcan yet. Fer corn sakes...
Yeah Vulkan has the potential to utilize the system resources better. Doom 2016 and the new Doom are essentially the poster child examples of just good Vulkan can be. Vulkan also applies a different load on your CPU. I would recommend checking the difference in CPU usage under both APIs. If your CPU is overclocked it could be exposing a CPU instability.
 

cybereality

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Yes, Vulkan removes many of the CPU bottlenecks inherent with older APIs, and also allows for real multi-threading, that didn't work well in GL or even DX11.

So what you are seeing in Doom, for example, is the real power of your GPU, without the CPU/API overhead.
 

/dev/null

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Yes, Vulkan removes many of the CPU bottlenecks inherent with older APIs, and also allows for real multi-threading, that didn't work well in GL or even DX11.

So what you are seeing in Doom, for example, is the real power of your GPU, without the CPU/API overhead.
This is exactly it. Vulkan was designed to be able to feed your GPU better with your CPU. It tends to help lower end cpus more.
 

prime2515102

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FRAPS hasn't been updated since 2013 and is basically dead, for all intents and purposes.

MSI Afterburner/RivaTuner is the current software you should be using, and much better than FRAPS.
I had worked with that once when I was first overclocking this GPU but I forgot how to do it so I tried for a quick test. I'll have to get that going again (I remember it giving really good info).
Yeah Vulkan has the potential to utilize the system resources better. Doom 2016 and the new Doom are essentially the poster child examples of just good Vulkan can be. Vulkan also applies a different load on your CPU. I would recommend checking the difference in CPU usage under both APIs. If your CPU is overclocked it could be exposing a CPU instability.
It's definitely the GPU. I dropped the OC from +150 (it wasn't actually going that high) to +100 and it's rock solid now (I still have some tweaking to do, that was a quick fix setting). I did think it was the CPU at first though, then I thought maybe my 7 year-old PSU, but nope.
This is exactly it. Vulkan was designed to be able to feed your GPU better with your CPU. It tends to help lower end cpus more.
I was reading that about mantle when it first came out and I tried the Ashes of the Singularity demo with a Radeon 7970 and i5-2600k at 4.5Ghz (I think) and there was barely an improvement so I guess I kind of wrote it off. I think the GPU was the bottleneck there though and not the CPU.

With Doom though, I'm now running a i7-7700k at 5Ghz with the 1080 so I wouldn't have thought there would be much of a bottleneck on the CPU. I mean, the framerates are still well beyond acceptable anyway, I'm just shocked at how much higher they went.

I have a lot of reading to do. I used to be on top of this stuff but I lost interest a while back because PC's got pretty stale with the lack of competition in recent years - when I got the parts for my current build they sat here for a month because there was nothing exciting about it at all (even though it was my first custom water cooled system). Back in the day I would have had it built before the UPS guy left! lol The competition from AMD's comeback has got me interested even though my next upgrade is likely a year off.
 

Krenum

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Vulkan is pretty easy to run, all my ARM based machines run on it. They run 3D applications using Vulcan better than OpenGL or D3D.
 

Rizen

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Vulkan isn't harder to run, it's harder to implement for developers as it's a lower level API than traditional DirectX.
 
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