'Graphic North Bridge' PlayStation 4's Custom Chip?

[onQ]

If anything GNB sounds like an updated version of the Wii U's GPU die, that's probably just a coincidence though.

If you are basing your information on the Indeed.com CV, isn't the line stating "GNB is targeted for 20nm technological library with GF foundaries" enough to rule it out for any of the upcoming consoles?

I don't think that's the PS4's GNB , the GNB that I think is in the PS4 is Starsha & it's 28nm.

First thing first, sweetvar's info may have been misinterpreted. He said 5 SIMDs. Not 5 CUs. In GCN terms, 1 CU has 4 SIMDs. This Starsha thinggie has 5 SIMDs ("just" 1 extended CU ?). There is no 410 GFLOPs here if that number is calculated from 4 CUs.

The 14+4 CUs rumor still matches Cerny's 18 unified CUs announcement. 18 is aplenty. They run assorted compute jobs together, compared to fixed partitioning implied by 14+4.

Now back to Starsha...



RemotePlay, video and audio stuff makes use of the video and audio decoders. The AMD CPU can switch to run the web browser easily.

Head tracking, voice recognition, ... can be run by the Jaguar vector engines or the GPU's CUs.

I suppose the ARM CPU could also have a vector engine to handle security operations, but I don't think they need 410GFLOPs for it.



If we prune the rumors based on the apps we know so far, there is little need for an additional compute unit. It would be extra programming hurdle to use Starsha (why not SPUs ?). They want simplicity.

I did notice that according to Cerny's interview, the secondary chip is there partly for energy efficiency. So perhaps Jeff Rigby has partial credits.

If we believe in every single rumor, it will be like playing Demon's Souls. Every time we have to restart the thread albeit capped at half the patience and sanity. It's probably best to keep Starsha aside and wait for more info. Sweetvar's tip may have been too early (i.e., killed) as one of the posters pointed out.

I don't think the 5 SIMD's are the same as the GCN CU SIMD's with 16 ALU's because if 5 of them = 320 ALU's there must be 64 ALU's to each SIMD & what's being seen as a GPU-like Compute module by Eurogamers could be the SIMD Array of the Starsha GNB.

as for Starsha being too early you could be right but Starsha also was the last bit of info that he added months later after he broke the news that PS4 would be using Jaguar cores for it's CPU, I think it was around October of last year.

 

[Love_In_Rio]

I get that part, it just seems to me that the GNB in the PS4 is what Sony is calling the second custom chip.

like they actually put an APU & GPU together for the PS4 but used the CU's of the GNB from the APU as part of the secondary chip & it's what VGleaks & Eurogamer seen.

And then where is the northbridge of the gpu put together with the apu?.Two northbridges?Because you are describing a PC in a chip...

 

[onQ]

And then where is the northbridge of the gpu put together with the apu?.Two northbridges?Because you are describing a PC in a chip...

I'm not sure what make you think that it would have to be 2 nouthbridges.

 

[tunafish]

Let's try this again.

Look at that image. GNB is not the second chip, because GNB is a part of the first chip. This is how it is in all the existing AMD APUs -- the APU die consists of two distinct parts, the actual CPU cores, and the GNB that talks to memory and which contains the GPU.

The GNB is not what you are talking about, because it is not a discrete chip.

 

[onQ]

Let's try this again.

Look at that image. GNB is not the second chip, because GNB is a part of the first chip. This is how it is in all the existing AMD APUs -- the APU die consists of two distinct parts, the actual CPU cores, and the GNB that talks to memory and which contains the GPU.

The GNB is not what you are talking about, because it is not a discrete chip.

But that wouldn't match up with a GPU-like Compute Unit paired up with the CPU or the 14+4 leaks.

The APU is custom made so it could be a lot different from what's in that picture.

it could be more like the Trinity APU.

 

[patsu]

Isn't your APU diagram like the yellow box in tunafish's post ?

 

[onQ]

Isn't your APU diagram like the yellow box in tunafish's post ?

See the UNB?

 

[patsu]

I can't tell what's in the lower right corner. Your last block diagram still looks like the yellow box to me.

 

[Exophase]

I can't tell what's in the lower right corner. Your last block diagram still looks like the yellow box to me.

Lower right corner is four AMD Fusion branded DDR3 DIMMs.

See the UNB?

Are you familiar with what a north bridge is?

It's what connects a CPU to memory and other high speed interfaces (in other words, contains the memory controller). The only reason it's called unified in this case is because it serves both the CPU and the GPU. There's nothing special about this, it's a given that the PS4's APU chip will have one.

GNB apparently is extended to include, in addition to the usual north bridge features, media encode and decode blocks and other bits of uncore. I don't know why you think something called GNB also contains some magic compute capability when the highlights section in sweetvar's post leave out anything like that. You confuse things further by finding a poorly written (as in, contains poor English) summary on someone's resume and here it becomes totally unclear what point you're actually trying to make. Maybe you're confused because the description says this GNB contains south bridge functionality. That's a given since it's for Kabini (later the resume makes this clear) which we know - unlike PS4 - is a complete SoC that has low speed peripheral I/O (the stuff we call traditionally "south bridge") embedded on the chip itself.

 

[BRiT]

northbridge

You keep using that word. I do not think it means what you think it means.

 

[onQ]

Lower right corner is four AMD Fusion branded DDR3 DIMMs.



Are you familiar with what a north bridge is?

It's what connects a CPU to memory and other high speed interfaces (in other words, contains the memory controller). The only reason it's called unified in this case is because it serves both the CPU and the GPU. There's nothing special about this, it's a given that the PS4's APU chip will have one.

GNB apparently is extended to include, in addition to the usual north bridge features, media encode and decode blocks and other bits of uncore. I don't know why you think something called GNB also contains some magic compute capability when the highlights section in sweetvar's post leave out anything like that. You confuse things further by finding a poorly written (as in, contains poor English) summary on someone's resume and here it becomes totally unclear what point you're actually trying to make. Maybe you're confused because the description says this GNB contains south bridge functionality. That's a given since it's for Kabini (later the resume makes this clear) which we know - unlike PS4 - is a complete SoC that has low speed peripheral I/O (the stuff we call traditionally "south bridge") embedded on the chip itself.

New Starsha GNB 28nm TSMC
Milos
Southern Islands

DX11
SM 5.0
Open CL 1.0
Quad Pixel pipes 4
SIMD’s 5
Texture Units 5TCP/2TCC
Render back ends 2
Scalar ALU’s 320

Seems like he is describing the GNB to me & why do people keep talking about 'Magic compute'?

Eurogamers & VGleaks seen something that's there for Compute.

 

[Exophase]

Seems like he isn't describing the GNB there because the second part of his post says highlights of the GNB which only refer to traditional uncore features. If these things were all features of the GNB then why would there be a separate section to outline its highlights? Why not just one big list of GNB features? Furthermore, the features in the first section are clearly referring to parts that only make sense in the context of a GPU - quad pixel pipes? Texture units? Render back ends? So why is it that you've only chosen the part about SIMDs to refer to something that belongs to the GNB? Either you think they're calling the whole APU GNB (which is highly silly but not even as silly as what you think) or you think it's only the second part that talks about GNB.

The post is a vague collection of snippets but the much more reasonable way to parse it is that it contains those three things at the top. A GNB they named "Starsha", whatever "Milos" is, and a Southern Islands GPU.

Unfortunately you like to employ very selective reading to try to get what you want out of a text. And add some very strange interpretations on top of it.

People say "magic compute" because it makes no sense to have compute units that are separate from the GPU. That's a bad design idea, but somehow people don't see this. I guess all because of an old rumor of 14 + 4 GPU + compute only CUs that you won't let die? Sony revealed there are 18 CUs and hasn't said anything about 4 of them being cut off from the main supply so it's pretty clear whoever thought that was mistaken or (less likely) the design changed.

 

[onQ]

Seems like he isn't describing the GNB there because the second part of his post says highlights of the GNB which only refer to traditional uncore features. If these things were all features of the GNB then why would there be a separate section to outline its highlights? Why not just one big list of GNB features? Furthermore, the features in the first section are clearly referring to parts that only make sense in the context of a GPU - quad pixel pipes? Texture units? Render back ends? So why is it that you've only chosen the part about SIMDs to refer to something that belongs to the GNB? Either you think they're calling the whole APU GNB (which is highly silly but not even as silly as what you think) or you think it's only the second part that talks about GNB.

The post is a vague collection of snippets but the much more reasonable way to parse it is that it contains those three things at the top. A GNB they named "Starsha", whatever "Milos" is, and a Southern Islands GPU.

Unfortunately you like to employ very selective reading to try to get what you want out of a text. And add some very strange interpretations on top of it.

People say "magic compute" because it makes no sense to have compute units that are separate from the GPU. That's a bad design idea, but somehow people don't see this. I guess all because of an old rumor of 14 + 4 GPU + compute only CUs that you won't let die? Sony revealed there are 18 CUs and hasn't said anything about 4 of them being cut off from the main supply so it's pretty clear whoever thought that was mistaken or (less likely) the design changed.

No I think Starsha is a GNB SoC that contains the features that was listed below it & it's part of the PS4's APU.

 

[Sonic]

Seems like he is describing the GNB to me & why do people keep talking about 'Magic compute'?

Eurogamers & VGleaks seen something that's there for Compute.

Why are you clinging onto this one bit of speculation when we can largely disregard it given the current evidence at hand? It's almost like you're not able to comprehend that this rumor has been discussed endlessly before and the likely conclusion is that there's no CU's tacked onto the GNB within the APU. Given that the GNB is part of the APU it makes little sense for CU's to be there. The whole 14+4 thing is absolutely stupid and the machine is much better off being able to have all CU's work on graphics or compute.

 

[onQ]

Why are you clinging onto this one bit of speculation when we can largely disregard it given the current evidence at hand? It's almost like you're not able to comprehend that this rumor has been discussed endlessly before and the likely conclusion is that there's no CU's tacked onto the GNB within the APU. Given that the GNB is part of the APU it makes little sense for CU's to be there. The whole 14+4 thing is absolutely stupid and the machine is much better off being able to have all CU's work on graphics or compute.

I don't recall there being any evidence that what Eurogamers & VGleaks spoke of not being there.

 

[AlphaWolf]

I don't recall there being any evidence that what Eurogamers & VGleaks spoke of not being there.

Other than the Sony announcement.

 

[Exophase]

No I think Starsha is a GNB SoC that contains the features that was listed below it & it's part of the PS4's APU.

I don't know why you're not getting this but the concept of a GNB SoC makes no sense. It's part of the APU. Not a separate chip. The days of non-integrated north bridges are far behind everyone in the industry.

 

[Sonic]

I don't recall there being any evidence that what Eurogamers & VGleaks spoke of not being there.

The lack of evidence of what they spoke of being there is enough evidence for me.

 

[onQ]

Other than the Sony announcement.

You mean the announcement when they also spoke about the 2nd chip that does background processing?

I don't know why you're not getting this but the concept of a GNB SoC makes no sense. It's part of the APU. Not a separate chip. The days of non-integrated north bridges are far behind everyone in the industry.

I said it was part of the APU

The lack of evidence of what they spoke of being there is enough evidence for me.

"GPU-like Compute module, some resources reserved by the OS"

Sound like the 2nd chip that's doing background processing to me.

 

[Exophase]

First you say Starsha or "GNB" has extra compute resources. Then you say it's an SoC. Then you say it's part of the APU. Then you say it's the background southbridge chip that has extra compute resources. Make up your mind, you're all over the place...