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Doom Vulkan with different CPUs

Caporegime
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There have been a lot of posts recently showing confusion over what the new Vulkan and DX12 APis bring to the table. Some people mistakenly seem to think there is some kind of magical instantaneous performance boost and any card that doesn't get faster is somehow not supporting the API. this is somewhat flawed logic, the primary advantages, at least in the near term, is reduced CPU overhead. The multi-threading and reduced draw call overheads reduce any CPU bottlenecks.

if performance doesn't increase, that merely means there isn't a CPU bottle-neck with the specific GPU and CPU combo. This is very apparent when looking at a low-end GPU combined with a high end CPU which sadly is frequently the case in reviews. Things get very interesting when the CPU power is reduced

doom.png


here we can see with a last CPU the 1060 doesn't see a big gain in performance, which indicates there is no CPU bottleneck and the OpenGL have a low overhead and well optimized. In contrast, the 480 sees a very healthy gain in performance which means the card is suffering some kind of bottle neck in OpenGL. A combination of high driver overhead and limitations of the GPU front-end coming to play.

However, with older slower CPU's even the 1060 starts to see very healthy gains in performance using Vulkan, in fact performance keeps very close to the experience with the fast CPU. The 1060, Vulkan API and the NVidia Vulkan drivers are doing exactly what is expected - reducing the bottleneck of the CPU.

The 480 still see a good benefit form using Vulkan but even there the performance is degraded significantly with slower CPUs. The effect is so big that the 1060 commands a significant performance lead, be it in openGL or Vulkan over the 480.



This is soemthign to keep in ind if you have an older computer and are looking to buy one of the new mainstream GPUs . Performance with a very high end CPU may not be painting the true performance picture.
 
Soldato
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Isn't thi showing that even with no CPU bottleneck the 480 gains a lot with Vulkan, whereas the 1060 does not?

I'm referring to the 6700K results. I'd assume a 6700K at 4.5 Ghz would not be a bottleneck to the 480...
 
Associate
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would be interesting to see which CPUs show the bottleneck.

I run an old CPU - 2011 and while I do see quite high FPS ( in 1440 p, ultra in Doom for example ) I do wonder if there is a bottleneck.

Not that it really matters though :D
 
Soldato
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So basically you need a £300 CPU to max out the 480 whist any old cpu will give great performance with nvidia. Seems to me Nvidia have the edge when it comes to driver optimiazation.
 
Soldato
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This is beginning to give more credence to the claims on this forum about better scope for improvement with the RX480. Assuming more developers utilise Vulkan.

Plus when you add in fast multi core CPU's from Intel and maybe Zen. DIRECTX 12 & Vulkan gain even more.

Some people seem to be forgetting these api are not just about the GPU, they are also designed to better make use of the CPU, in return giving the GPU more freedom to pull it's weight.

This will explain why on the slower CPU's on OP Vulkan doesn't gain much.
 
Caporegime
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Isn't thi showing that even with no CPU bottleneck the 480 gains a lot with Vulkan, whereas the 1060 does not?

I'm referring to the 6700K results. I'd assume a 6700K at 4.5 Ghz would not be a bottleneck to the 480...

That depends on the quality of AMD's OpenGL drivers which are notoriously bad.

The performance improves can only come from reducing a bottleneck. the primary one being the CPU and the number of draw calls but the GPU front end such as the command processor can be limiting as well. AMD were hinting that they did a lot of work in improving the command processor but it isn't very evident from reviews so far. The performance delta between DX11 and DX12 should be smaller with Polaris than with Fiji and Hawaii but that doesn't look to be obvious.
 
Soldato
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All I see is Nvidia owning with older CPUs where Vulcan/DX12 is supposed to gain you more performance, Nvida are doing it, AMD not so much.

So on these results I could not reccomend an 480 to anyone on older CPUs.
 
Caporegime
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Doesn't explain why some nvidia users are getting worse performance when running Vulkan.

Bug in the game or driver, who knows. If performance degrades then it is obviously not normal and it needs fixing. Same when you see DX12 results slower than DX11, that means the developer has failed to optimize their code patch as well as the DX11 driver code-path. There is nothing wrong with the DX12 drivers or hardware when that happens, it quiet natural that a game developer under time pressure can;t do as good a job as a nvidia engineer who knows the architecture details to a T.
 
Caporegime
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This is beginning to give more credence to the claims on this forum about better scope for improvement with the RX480. Assuming more developers utilise Vulkan.

Actually I think it shows somewhat the opposite. AMD can still do a lot with OpenGL and Dx11 drivers to close the performance gap.


The other thing is in the future there may be games where the number of draw call increases substantially. Under those scenarios even Nvidia's DX11 and OpenGL might start becoming bottlenecked by the CPU and thus the DX12/Vulkan APIs will facilitate much better performance improvements. As the moment, Nvidia's driver stack simply means that DX12/Vulkan don't always lead to such gains.

One of the exceptions to this is the DX12 Timespy benchmark that has massively increased draw-calls. PascalGPUs do really well at leveraging the API
 
Man of Honour
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Doesn't explain why some nvidia users are getting worse performance when running Vulkan.

There might be some other issues but DF accidentally touched on one of the big reasons IMO - there seems to be some funkiness with the V-Sync implementation at a low level in the Vulkan API which is absolutely killing performance on nVidia setups:

https://youtu.be/27zvYGSGrng?t=237 (look at the frametime graph)

While the AMD cards it seems to be forced off at the Vulkan API level:

https://youtu.be/27zvYGSGrng?t=98

So at the very least id/khronos/nVidia need to fix that so we can see the true performance (or something closer to it).
 
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Soldato
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So either the cpu's are bottlenecking the 480

OR

The 480 is attempting to offloading some work to the CPU that the 1060 does not and it can't keep up with demand.


I have to say ... that is quite a nasty looking graph.

Is there anything else to this, like stupid levels of tessellation going on or something, that isn't immediately obvious here.
 
Caporegime
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Interesting and confirms what I tested with my 6850K. Vulkan and OGL are pretty much swapping from being the winner depending on what part of Doom I am at. No CPU bottleneck, so hence why I am not seeing gains with Vulkan and pretty much a tie as shown from my last Doom vid.

Nice find D.P
 
Man of Honour
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Is there anything else to this, like stupid levels of tessellation going on or something, that isn't immediately obvious here.

Nope - might be some other factors but largely seems to be a bug with V-Sync that for some reason no one seems to have noticed.
 
Soldato
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The rest of the results show very little in it between dx11 for nvidia and AMD quite surprised tbh maybe the extra driver work that went into the new GPU.

Conclusion
Well I didn’t manage to run into any compatibility issues with my Radeon RX 480 on these old systems but I did end up finding some interesting results. For the most part the 480 didn’t fare nearly as poorly against the GTX 1060 as I thought it might. There were of course exceptions though such as Doom and Ashes of the Singularity using DX11.
It was interesting, although admittedly not all that surprising, to see just how much slower these new mid-range graphics cards were on these old quad-core systems. It’s also been a long time since I’ve seen the Core i5-750 face the Phenom II X4 955 and honestly I had forgotten how much better the Intel processor was for gaming. The performance difference is likely being amplified by the use of modern games that take full advantage of quad-core processors, with the exception of ARMA 3.
In short it appears you’re going to see similar performance margins between the RX 480 and GTX 1060 on older hardware. On that note you’re also going to see considerably greater performance when using a modern processor or at least a relatively modern processor overclocked. I didn’t have time to overclock the Core i5 and Phenom II X4 processors for this video but perhaps I can do a more indepth video in the near future featuring more GPU and GPU configurations if you guys are keen to see it.

http://www.hardwareunboxed.com/gtx-1060-vs-rx-480-in-6-year-old-amd-and-intel-computers/
 
Associate
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This suggests that the RX 480 has a lot more potential then. The GTX 1060 is showing almost no CPU bottlenecking between old and new generations of API. The RX 480 meanwhile gets beaten using the old API but then blasts past the GTX 1060 when using the new one.

iwanttobelieve.jpg
 
Soldato
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The interesting thing here, is that graph taken in isolation makes the RX 480 look total trash for those on older hardware. But then if you goto the link, and look at the other graphs it is NOTHING like the graph shown for doom. The 480 is mostly behind the 1060 for sure, but certainly nothing like the graph posted at the top.
 
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