DF: Unreal Engine 5 Matrix City Sample PC Analysis: The Cost of Next-Gen Rendering

adamsapple

Banned

It's early days for Unreal Engine 5 and its incredible new rendering technologies, but the technology is now available for all along with the Matrix Awakens cityscape - which is available as a project for all developers to experiment with. In this video, Alex goes deep on the key systems that set UE5 apart, how they scale and how performant they are right now - with some eye-opening results.
 
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adamsapple

Banned
* Hosted by Gaf favorite Alex
* Sample of core UE5 technologies on display
* Some areas of Nanite are still in active development. Usage for Foliage and characters is in development right now.
* Hardware / Software Lumen look very similar but software isn't as accurate and misses character reflections. Hardware also traces much farther than software.
* Software also has trouble shading insides of things and night lighting is only captured in screen space. Hardware is accurate.

* Shader compilation issues present. After those clear up, you're still very CPU limited.
* Hardware Lumen is 32%~40% slower than Software.
* UE5 is very heavily single threaded. Processor frequency is more important for performance than number of cores.

* Mid range PCs are severely CPU limted, averaging 30 FPS but much worse during movement.
* Image breakup on console is worse than PC. Alex thinks TSR quality is better on the PC demo.
* Reflections etc is generally same as "High", shadow map quality is lower than PC's high/medium.
* PS5/SX/SS are CPU limited in the demo, hence the drops.
 
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Dang, have to agree with Alex. The heavy CPU limited nature of UE5 makes me very nervous. Generally I feel games with CPU limitations are much harder to optimise than those that tax GPU the most. Plus, this demo is probably very light on gameplay/system/AI/scripting related work that would be present in a complete game, which would put further stress on the CPU.

I am officially on the "UE5 proliferation might be not so good news" boat now.
 
Enjoy 60fps on console while it lasts, once Unreal 5 games start to release in 2027 it's right back to 30fps. Even on PC, high framerates will be a hard challenge if it's heavily single threaded and CPU bound.

The fact that the Nanite tech isn't fully functional already is a massive red flag.

Even the Series S is CPU bound? Wat?
 
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Razvedka

Member
As if Desktop CPUs were that much better than a mobile Zen 2.
Yeah I was under the impression that the Zen 2 cores in the consoles were very well received, in particular when paired with the dedicated silicon for things like audio, decompression, I/O etc. Even if they're 'mobile CPUs' they're still Zen 2, have razor thin APIs, and have oodles of work taken off their plate out the gate.
 
So there's no PC that can push 60 [locked] in this? Not so epic get back to the drawing board.

Cricket No GIF by Rohit Sharma
 

ethomaz

Banned
Yeah I was under the impression that the Zen 2 cores in the consoles were very well received, in particular when paired with the dedicated silicon for things like audio, decompression, I/O etc. Even if they're 'mobile CPUs' they're still Zen 2, have razor thin APIs, and have oodles of work taken off their plate out the gate.
Console Zen2 have half the cache of desktop Zen2.
There are others differences but that alone is the main driver for performance.

Is not AMD that doubled the cache of a Zen 3 processor recently and got big boost in performance in some games?
 
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Skifi28

Member
I was expecting PC to blow past these limitations. This is disappointing and concerning for the future. Perhaps UE5 isn't the end of all other engines as I've been told.
 

ethomaz

Banned
ooof...
does ps5 version use software or hardware lumen?
Hardware.

Software is used in GPUs that doesn't have Hardware RT.
The documentation says if Hardware RT is detected it will use automatically Hardware Lumen... there is no option to change that yet.

In any case Software Lumen looks like PS2/PS3 lol
 
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But do you really think 30fps will become a thing again?
My money was always on 30fps coming back. Unreal 5 just seems to remove the choice that devs would have to make.

But 30 frames never left. You just now have the choice of the game looking like shit and rendering in low resolutions to hit 60 or looking better and in higher res and hitting 30. Nearly every game is cross gen as well
"Looking like shit", come on...
 
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RespawnX

Member
These mobile CPUs on console will have a hard time with UE5.

UE5 won’t last long on market if they don’t serve developers needs. Reading all those articles about missing technology and performance issues at UE5. This engine don’t seems ready for productive development. It‘s hilarious to promote a single threaded engine in 2022.

Last time I saw such a bottleneck it was in CryEngine v1 and not half as pronounced - 15 years ago. This engine seems lrushed and I assume Tencent made a lot of pressure to get high early adopter rates for UE5. At this point the „release“ is more like an actual alpha.

This situation could lead in a lot of development struggle. Specially for Microsoft as they seem focused on UE5 for a lot of projects
 
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ethomaz

Banned
UE5 won’t last long on market if they don’t serve developers needs. Reading all those articles about missing technology and performance issues at UE5. This engine don’t seems ready for productive development. It‘s hilarious to promote a single threaded engine in 2022.

Last time I saw such a bottleneck it was in CryEngine v1 and not half as pronounced - 15 years ago. This engine seems lrushed and I assume Tencent made a lot of pressure to get high early adopter rates for UE5. At this point the „release“ is more like an actual alpha.

This situation could lead in a lot of development struggle. Specially for Microsoft as they seem focused on UE5 for a lot of projects
It is not a single-thread engine... Nanite and Lumen are... I understand the reason... the others Cores of the CPU are left to developer well run their game logic and stuffs.
You can't make a Engine that one of it features uses several cores not letting anythingt o developer.

If you make a Engine that uses all the CPU resources just from enabling it features then you are dead on start.
 
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ethomaz

Banned
Because it has a drastically less powerful GPU?
But it is CPU bound... it is not even using 100% of the GPU... in most test on PC it uses 50% because CPU is holding it.
It is probably not using 100% of the GPU in either PS5 or Series X.

So GPU power in this case is not related to the performance.
 
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But it is CPU bound... it is not even using 100% of the GPU... in most test on PC it uses 50% because CPU is holding it.
It is probably not using 100% of the GPU in either PS5 or Series X.

So GPU power here is not even related.
If it's holding the GPU of the Series S back than how will it handle a RTX 3060/3070/3080/etc or the new GPUs that are on their way?

This is "good" for the Series S, you seem to be misunderstanding my point.
 
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ethomaz

Banned
The article.


With all of this in mind, where do we stand with this first look at a release version of Unreal Engine 5? The quality of the rendering is superb, Lumen and Nanite are delivering the generational leap in fidelity we want from the latest hardware, but I am concerned about CPU performance, where we can easily find limits even with the most powerful processors on the market. Of course, this is just a demo sample and not a final product but even so, I'm surprised at the apparent reliance on single-thread CPU performance - I'm concerned that attaining 60fps in UE5 titles for PC, let alone consoles, is going to be extremely challenging. However, ultimately, this is just a single example of the engine in action - and of course, the technology remains in a constant state of development, with many improvements to come.
 
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FireFly

Member
Yeah I was under the impression that the Zen 2 cores in the consoles were very well received, in particular when paired with the dedicated silicon for things like audio, decompression, I/O etc. Even if they're 'mobile CPUs' they're still Zen 2, have razor thin APIs, and have oodles of work taken off their plate out the gate.
Zen 3 is about 25% faster than Zen 2 on PC, for gaming. But Zen 2 on PC is itself clocked 20%+ more than on the console CPUs. So Zen 3 could be 50% more powerful than the console CPUs.
 

ethomaz

Banned
If it's holding the GPU of the Series S back than how will it handle a RTX 3060/3070/3080/etc or the new GPUs that are on their way?
I can only talk about the RTX 3080 (because I only read benchmarks with that GPU but it should be the same with similar GPUs)... it works below 50% GPU usable in this demo due the CPU.
 
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Dampf

Member
* Hardware Lumen is 32%~40% slower than Software.

On the CPU. On the GPU, HW and SW Lumen perform very similar. You bascially get the much more precise HW-Lumen GI and reflections for free if you card supports HW-Raytracing.

Right now it appears like BVH creation on the CPU is only running on a single thread. This will very likely be much further optimized in a full game release.
 

mrcroket

Member
But CPU on consoles are very way better optimices than PC even compared to vulkan api, just look at the ps4 and xbox one with their shitty cpu and the games that their run.
 

ethomaz

Banned
uch, seeing how heavy is ue5 on cpu and how badly scale with cores number maybe massive exodus to ue5 for so many studios is little premature
They have to optimize but going on more cores is risk.
Devs needs most of cores of your CPU for the game so an Engine using more than 1 is really not good unless you have a CPU with several cores like 16.

I guess the max UE5 can use for Nanite/Lumen in a 8-core CPU will be 2 cores but they need to think in people with 4-core and 2-core CPUs.
 

ethomaz

Banned
On the CPU. On the GPU, HW and SW Lumen perform very similar. You bascially get the much more precise HW-Lumen GI and reflections for free if you card supports HW-Raytracing.

Right now it appears like BVH creation on the CPU is only running on a single thread. This will very likely be much further optimized in a full game release.
The difference between HW and SW Lumen is generational imo.
SW Lumen is like two generations behind.
 
This video is selling short how impressive the performance of this is on consoles
I don't really see how performance of this can be termed "impressive" on ANY system. All consoles are CPU limited, even the XSS, which means that even the very limited XSS GPU is not running full tilt (let alone the PS5 and XSX). And consoles are CPU limited similar to how a Ryzen 3600 is (ryzen 3600 is generally considered a good match for the console CPUs this gen).
 

ethomaz

Banned
But CPU on consoles are very way better optimices than PC even compared to vulkan api, just look at the ps4 and xbox one with their shitty cpu and the games that their run.
Consoles APIs has way less overhead on CPU than PC if that is what you mean.
That is because people calls it Code to Metal (that is not really Metal because you should program in Assembly to be Code to Metal... there is some abstraction layer, aka overhead, in consoles API yet).
 
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winjer

Gold Member
As if Desktop CPUs were that much better than a mobile Zen 2.

Yes they are.
For once, the desktop Zen2 are clocked higher. Almost 1GHz more than on consoles.
And mind you, that UE5 loves clock speed more than core count.
Then there's the L3 cache. A Zen2 3700X has 16+16MB. Consoles have just 4+4MB.
And to make things worse, consoles have much higher memory latency. A PC desktop Zen2 CPU without memory tweaking, gets 70-80ns of latency.
The PS5 has a latency abore 140ns. This and the lack of L3 cache means that cache misses are much higher on consoles.

Edit:
Some people are saying UE5 is bound by a single thread. But that is not exactly the case.
UE5 can spread workload across many threads. But there is probably some execution bottleneck that limits it's performance.

 
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Dampf

Member
The difference between HW and SW Lumen is generational imo.
SW Lumen is like two generations behind.
It really depends. In some instances Software Lumen is pretty close to Hardware, but man there are times when it's a generational difference for sure.

It really seems like running UE5 on an RTX/RDNA2 card will get you many significant benefits in terms of visual quality without lowering performance, which is a really good thing. I am pretty sure Epic and HW-Vendors will speed up BVH creation on the CPU significantly in the coming future.
 

A.Romero

Member
Well, top of the line graphics obviously come at a cost. Hardware advances faster than products are developed and reach the market so I think it's best current hw can't cope with software demands at early stages.

Also I have expectations for next year's CPU architectures.
 

ethomaz

Banned
Yes they are.
For once, the desktop Zen2 are clocked higher. Almost 1GHz more than on consoles.
And mind you, that UE5 loves clock speed more than core count.
Then there's the L3 cache. A Zen2 3700X has 16+16MB. Consoles have just 4+4MB.
And to make things worse, consoles have much higher memory latency. A PC desktop Zen2 CPU without memory tweaking, gets 70-80ns of latency.
The PS5 has a latency abore 140ns. This and the lack of L3 cache means that cache misses are much higher on consoles.
I have no ideia where people get that ideia mobile Zen2 is like Desktop Zen2.
Maybe there is a low end Desktop Zen2 that perform lower than a high-end mobile Zen2 but that is all.

Consoles Zen2 is in the low to mid-end side of mobile Zen2.
 
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Md Ray

Member
These mobile CPUs on console will have a hard time with UE5.
Even the 10900K is having a hard time here.
Because it has a drastically less powerful GPU?

Unreal 5 engine screams 30fps at this point, something isn't right.
It doesn't matter how powerful (or less powerful) the GPU is, it is still going to be CPU-limited.

For instance, if a scene runs at 35fps due to being CPU-bound on Series X, you're going to see similar frame-rates on Series S as well. Having paired with less powerful GPU won't automatically increase the frame-rates.
 

ethomaz

Banned
Single core limited, which in 2022 is wild, and not really acceptable.
I explained before an Engine can't use a lot of cores because you need most of the cores for the game logic and stuffs the developer will put in the game.
But I agree it should be an option to developer choose how many cores Nanite/Lumen could use in their game.

Does it make sense to focus an engine on frequency rather than cores in today’s environment?
Kinda makes? I mean most cores should be free to developer create their game and not to Engine use.

Said that UE5 can do better... give more options, etc.
 
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winjer

Gold Member
I have no ideia where people get that ideia mobile Zen2 is like Desktop Zen2.
Maybe there is a low end Desktop Zen2 that perform lower than a high-end mobile Zen2 but that is al.

Consoles Zen2 is in the low to mid-end side of mobile Zen2.

Most people just see Zen2, and don't understand the rest.

The PC does have low level APIs, like DX12 and Vulkan.
But consoles do have APIs that go a bit lower. For example, the Xbox Series version of DX12 has a mode with a similar overhead to DX12 on PC. But then, it also has a mode that goes lower, exposing more low level instructions.
So consoles, in certain cases can regain some of the lost performance. But only on games made by studios with talent and money to spend on going on the lower API features.
 

Md Ray

Member
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