Turns Out PS4 Is Even MORE Powerful than Xbox One

[jgoldwood]

Sounds good... hoping to see some exclusive games that aren't dumbed down to show off the system's capabilities.

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[Mavrick]

What gaf says:

Although both upcoming game consoles Xbox One and PlayStation 4 are based on AMD hardware, only PlayStation 4 incorporates hUMA [Heterogeneous Uniform Memory Access] for supporting a shared memory space. This was explained by AMD's Senior Product Marketing Manager Marc Diana to c't [big German IT magazine] at gamescom. This should put the 3D-performance of PlayStation 4 much farther ahead of Xbox One than many have expected so far. AMD sees hUMA as a key element for drastic performance improvements in combined processors. AMD's upcoming Kaveri desktop processors support hUMA as well.

Behind the scenes, c't could hear from developers that the 3D-performance of PlayStation 4 is very far ahead of Xbox One.

Back in April, AMD manager Phil Rogers explained to c't that hUMA improves 3D-performance in particular. "Game developers have been eager to use very large textures for years. Until now they had to resort to tricks in order to package parts of larger textures into smaller textures. That is because today a texture has to be located in a special place of physical memory before the GPU can process it. With hUMA, applications can work with textures much more efficiently". AMD will give more details on hUMA at its upcoming developer conference in November.

hUMA: Heterogeneous Uniform Memory Access

Even with the integration of GPUs and CPUs into the same chip, GPGPU is quite awkward for software developers. The CPU and GPU have their own pools of memory. Physically, these might use the same chips on the motherboard (as most integrated GPUs carve off a portion of system memory for their own purposes). From a software perspective, however, these are completely separate.

This means that whenever a CPU program wants to do some computation on the GPU, it has to copy all the data from the CPU's memory into the GPU's memory. When the GPU computation is finished, all the data has to be copied back. This need to copy back and forth wastes time and makes it difficult to mix and match code that runs on the CPU and code that runs on the GPU.

The need to copy data also means that the GPU can't use the same data structures that the CPU is using. While the exact terminology varies from programming language to programming language, CPU data structures make extensive use of pointers: essentially, memory addresses that refer (or, indeed, point) to other pieces of data. These structures can't simply be copied into GPU memory, because CPU pointers refer to locations in CPU memory. Since GPU memory is separate, these locations would be all wrong when copied.

hUMA is the way AMD proposes to solve this problem. With hUMA, the CPU and GPU share a single memory space. The GPU can directly access CPU memory addresses, allowing it to both read and write data that the CPU is also reading and writing.

hUMA is a cache coherent system, meaning that the CPU and GPU will always see a consistent view of data in memory. If one processor makes a change then the other processor will see that changed data, even if the old value was being cached.

As well as being useful for GPGPU programming, this may also find use in the GPU's traditional domain: graphics. Normally, 3D programs have to use lots of relatively small textures to apply textures to their 3D models. When the GPU has access to demand paging, it becomes practical to use single large textures—larger than will even fit into the GPU's memory—loading the portions of the texture on an as-needed basis. id Software devised a similar technique using existing hardware for Enemy Territory: Quake Wars and called it MegaTexture. With hUMA, developers will get MegaTexture-like functionality built-in.

Originally Posted by zomgbbqftw

Our guy on the ground has heard this as well from multiplatform developers and publishers. Their PS4 game builds are significantly outperforming the Xbox One game builds.

Well explained:

Originally Posted by W!CKED

On a classical system you have a RAM pool and a VRAM pool that are physically speperated. Copying data from one pool to the other creates latency. The GPU is very good ad hiding latency. What it needs most is high bandwidth. The CPU on the other hand is extremely sensitive to latency. The CPU needs extremely low latency to work efficiently. Copying data from the RAM (CPU) to the VRAM (GPU) creates latency, but that's okay for the GPU. Copying data from RAM (CPU) to VRAM (GPU) and back to the RAM (CPU) creates even more latency. It's too much for the CPU. The copying alone takes longer than the computation wich makes this roundtrip highly ineffective.

Xbox360 and older APUs have a unified RAM. This means that the RAM is no longer physically seperated, but even though it's the same RAM chips, the system still distincts between memory partition for the differenct processors. You still need to copy the data between CPU partition and GPU partition, but this will be much more efficient than copying it between physically seperated pools. But it's still too much latency for a CPU, GPU, CPU roundtrip.

PS4 will have hUMA wich means that you no longer need a distinction between CPU partition and GPU partition. Both processors can use the same pieces of data at the same time. You don't need to copy stuff and this allows for completely new algorithms that utilize CPU and GPU at the same time. This is interesting since a GPU is very strong, but extremely dumb. A CPU is extremely smart, but very weak. Since you can utilize both processors at the same time for a single task you have a system that is extremely smart and extremely strong at the same time.

It will allow for an extreme boost for many, many algorithms and parts of algorithms. On top of that it will allow for completely new classes of algorithms. This is a game changer.

Further evidence: Sony joined the HSA (Heterogeneous System Architecture) Foundation originally co-founded by AMD while Microsoft has not:
http://hsafoundation.com

[Elandyll]

Given how much the (truly) unified Memory architecture helped the 360 this passt gen, I am actually very surprised they didn't go for it again this time around. Then again, it seems they pushed for DDR3 (68Gb/s) early (low bandwidth) and might have been caught by surprise when it was leaked that the PS4 was going to use GDDR5 (176 Gb/s).

Wonder if the 32 mb ESRAM cache (that probably negates hUMA) addition was a "bandaid", or part of the design all along?

[West E]

if the devs for the Sony exclusives can really push the envelope we can see some amazing graphics. I hope in 3 years i'm begging for a Last of Us remake ala FF7. LOL

[Matt S]

I'd double dip on Last of Us, if it truly took full advantage of this - and they'd need to rewrite the Ai code

[MerrickG]

Originally Posted by Elandyll

Wonder if the 32 mb ESRAM cache (that probably negates hUMA) addition was a "bandaid", or part of the design all along?

I know the differences between DDR3 and GDDR5, but I have to wonder how much of a hassle it would have been to replace DDR3 with GDDR5.

I don't know if MS chose not to go that route because:

a) It would have made the console too expensive (likely the case)

b) Would have required too many changes to the design.

[Blu-Dragon]

AMD is saying now that this isn't true and that they never made any statement about this to that magazine. Interesting.

http://www.neogaf.com/forum/showpost...&postcount=639

Response and Service Request History:

It's not as much that he was misquoted as much as he wasn't quoted at all. You can see the report at http://www.heise.de/newsticker/meldu...t-1939716.html , which everyone has been quoting, but there is no quote from Marc Diana here, it is either in need of confirmation (which is unlikely, since we cannot confirm hardware functionality for other companies), or is just a misinterpretation of the information given to the writer. If there was a quote there we could analyze it further, but they don't have any sort of exact quote, so I am pretty sure that they just tried to draw some conclusions (IE Kaveri supports hUMA, and Kaveri is coming out at the same time as the PS4, so PS4 supports hUMA, which is erroneous as any chip used by Playstation will be custom-made to their specs, and isn't a Kaveri chip).

In order to update this service request, please respond, leaving the service request reference intact.

Best regards,

AMD Global Customer Care

[Elandyll]

Originally Posted by Blu-Dragon

AMD is saying now that this isn't true and that they never made any statement about this to that magazine. Interesting.

http://www.neogaf.com/forum/showpost...&postcount=639

No.

The AMD rep (which is merely customer support) says that unfortunately there is no direct quote from Marc Diana, so it's impossible to know what he actually said and wether there was a misquote (I'm sure the CS guy is rather shocked that someone from the company would belittle one of their major clients - MS).

On the other hand, the CS says -nothing- about wether the PS4 has hUMA or not. He merely states that this whole article could possibly be relying on the assumption: PS4 comes at the same time as Kaveri, therefore it has Kaveri, therefore it has hUMA, which is a false assumption because the PS4 does not have Kaveri but rather a custom made SOC with Sony "Secret Sauce".

On the other hand, the specs of the PS4 and Sony's involvement in the HSA (Heterogeneous System Architecture) could lead one to think that the PS4 indeed -has- hUMA.

In the end, it all comes down to: Do we think the journalist is lying when he says that Marc Diana told him at Gamescom that the PS4 would be significantly more powerful for 3D rendering than the XB1 over time thanks to a key aspect of a 2014 tech brought by AMD, specifically hUMA?
The other possibility would be a major misscomunication, Marc Diana having shifted to their new desktop graphic cards line (Kaveri) in the middle of a PS4 conversation and somehow at one point mentionning that the Xbox One would not have this (hUMA).

http://www.heise.de/newsticker/meldu...t-1939716.html

[Blu-Generation]

The only thing I got out of all this is that PS4 is a super-charged bad ass. With or without hUMA.

But this we know already.

[Derb]

Originally Posted by jgoldwood

Sounds good... hoping to see some exclusive games that aren't dumbed down to show off the system's capabilities.

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