PS4 Has hUMA and Xbox One Does Not — Promises Better Performance For PS4

PS4 apparently one-ups Xbox One in performance due to hUMA

Posted By | On 22nd, Aug. 2013 Under News

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According to reports, the PS4 will incorporate hUMA, which stands for Heterogeneous Uniform Memory Access, into the system, and the Xbox One will not. According to AMD’s–the company behind hUMA–senior product marketing manager, this will give the PS4 a significant edge over the Xbox One.

If you’re unsure as to what it is exactly hUMA does, don’t worry, you’re not alone. Sources over at PSU found a good explanation:

“On a classical system you have a RAM pool and a VRAM pool that are physically separated. 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 separated, but even though it’s the same RAM chips, the system still distinct between memory partition for the different 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 separated 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.”

Source: Heise

Awesome Stuff that you might be interested in

  • Crusina .

    “we have to invest a lot in coherency throughout the chip, so there’s been io coherency for a while but we really wanted to get the software out of the mode of
    managing caches and put in hardware coherency for the first time on the
    mass scale in the living room on the gpu. ” –>hUMA is AMD’s definition of a unified memory implementation with certain features. It seems Xbox One has the same features implemented but they just don’t call it hUMA due to the extend of customization of the chip.

    Another quote
    “The AMD chips inside the PlayStation 4 and Xbox One take advantage of
    something called Heterogeneous Unified Memory Access (HUMA) ”

    Posted by a confirmed Xbox One Dev on Reddit:

    [–]XboxOneDevConfirmed XB1 Dev 28 points 4 hours ago*

    Somebodyhad PM’ed me earlier linking to the Ars article on how the PS4 has a
    big advantage over the Xbox one due to hUMA. This was apparently said by
    some AMD marketing manager.

    I haven’t heard of hUMA until today, so I went to look it up. The way I understand it is that in addition to having unified memory access (shared memory between CPU and GPU), which allows the GPU to read CPU memory, it is also a coherent cache system. To quote Ars, “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.”

    I remember reading something on this when I got my first alpha kit. I pulled up a couple of our internal white papers and it’s pretty clear that this was the exact implementation in the Xbox One’s memory system.

    Also I couldn’t find any sources where Marc Diana actually said PS4 supports hUMA and Xbox One doesn’t. Every media outlet reporting on this seems to source a single German article which I’m not inclined to believe.

    Can anyone explain to me why people are stating a single article from a German website to be fact? Oh yeah, crappy Journalism.

    • Wollverath

      Thanks for posting this, lots of people have been talking about hUMA and frankly I was scared about XB1 not having it. But now I have a reply, appreciate it. Btw don’t want to watch the whole video, any part should I skip to?

  • Scott Vater

    Hey man…just wanted to let you know if you see this that the Xbox One does NOT have hUMA…it has a unified memory architecture much like the Xbox 360. The developer doesn’t know what he’s talking about.

    Unified = CPU and GPU have their own separate partitions. The CPU can’t access the GPU RAM and vice versa.

    hUMA = CPU and GPU have their own partitions BUT they can access each others RAM at the same time.

    Basically say with the new consoles they have 8GB of RAM. With unified memory both the CPU and GPU have access to the 8GB pool of RAM. So lets say we have 2GB for the CPU and 6GB for the GPU. Both of these sections (2GB and 6GB) cannot be shared.

    With hUMA, however, the opposite is true. This is where it is different from unified memory (such as in the Xbox One). Using hUMA and the 8GB from above lets say that the RAM is again split 2GB CPU and 6GB GPU. The difference with hUMA is that the CPU and GPU can access the same blocks of RAM at the same time.

    At least this is my understanding of it after some extensive research. So the developer that said that the Xbox One has hUMA is incorrect. Xbox One has Unified Memory, which as explained above is totally different.

    The PS4 is the only console that has this. It is a HARDWARE limitation of the Xbox One so it can NEVER support it. hUMA is just one of the many things that Sony worked hand in hand with AMD on to further strengthen their console.

    The developer was wrong. When he said the Xbox One support unified memory he is right. Only problem is that unified memory does not equal hUMA.

    You might want to do some more research on the matter. Maybe I’m wrong but from what I can gather I’m not. Let me know what you find!


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