What is PS4's 14+4 CU thing all about? *spawn

[taisui]

this is complete crap. GPU resources are there to be used, the entire idea of "balance" changes when you change the context. They are execution resources there to do stuff, what ever that might be. Thats the beginning and the end of it, over time dev's will find the optimal use of execution resources for certain tasks with certain compromises.

i see the people trying to down play the difference is execution resources as the ones with the agenda.

Am I missing something or the 14+4 NOT came from Sony's Mark Cerny's very own mouth?

 

[Betanumerical]

If it was a vague as you suggest here Sony would never have bothered making it a bullet point for their dev presentations. Again, just because you lack the imagination and/or understanding of how their platform works in detail and as such can't fathom other bottlenecks for rendering doesn't somehow suggest Sony is wrong. I trust their dev docs and Cerny over forumites who suggest they know better.



Nobody suggested as much.



No. But I'm willing to bet Sony can.



Read my post again. I said they seem to have designed a machine around 14 CU's for rendering and then added extra CU's specifically for their GPGPU ambitions...with additional tweaks to help accommodate that.

The slide needs far more context and details, its a bit early to say that its only got 14 useful rendering CU's as you are suggesting. Not to mention that one of Cerny's example was using GPGPU for graphics. I have a feeling it might have to do with the triangle setup rate but I could be off the mark there.

 

[mrcorbo]

Is there anything stopping GPGPU operations from being directed at creating prettier pixels? We saw the SPUs being used in conjunction with RSX in PS3. What would stop developers from using 4CUs worth of ALU resources on image postprocessing or something similar? I don't think that just because ALUs are being engaged outside the graphics rendering pipeline that they couldn't still be used for graphics.

 

[astrograd]

The slide needs far more context and details, its a bit early to say that its only got 14 useful rendering CU's as you are suggesting.

Sony suggested it. Not me. I'm just going by their suggestion about how to best utilize the CU's in their design.

Not to mention that one of Cerny's example was using GPGPU for graphics. I have a feeling it might have to do with the triangle setup rate but I could be off the mark there.

It'd be great is DF could interview him again and try to get clarification on what is actually incentivizing devs to use it for non-graphics tasks (as he says in the first DF interview)

 

[Betanumerical]

Is there anything stopping GPGPU operations from being directed at creating prettier pixels? We saw the SPUs being used in conjunction with RSX in PS3. What would stop developers from using 4CUs worth of ALU resources on image postprocessing or something similar? I don't think that just because ALUs are being engaged outside the graphics rendering pipeline that they couldn't still be used for graphics.

Nope, infact i am led to believe it can sometimes be better as it removes some restrictions that the FF pipeline has.

 

[Rangers]

It'd be great is DF could interview him again and try to get clarification on what is actually incentivizing devs to use it for non-graphics tasks (as he says in the first DF interview)

He was cagy in the first interview and might be even more so in any follow up.

If he perceived people were trying to spin 14+4 as a negative, he'd completely clam up about it whatever the truth may be imo.

Perhaps I underestimate him though. I'm certain there's lots of ways to spin (including highlighting positive truths) any info.

 

[Rangers]

The PS4 can mask which CUs are used for certain jobs.

The PS4 also can reserve GPU memory (LDS/register space, etc.) on individual CUs for use by specific tasks.

The VSHELL has reserved memory on "several" CUs 100% of the time and I wouldn't be surprised if VSHELL tasks are masked to those CUs.

There's a graphics command queue dedicated to VSHELL and it can create high priority GPGPU tasks.

If I read this greek correctly, I'm thinking it implies Sony reserves a certain, probably similar (I'd even venture, possibly more, given history), amount of GPU for OS.

File under knock me over with a feather...

Some of us assume such things despite internet hyperbole to the contrary...

 

[Betanumerical]

If I read this greek correctly, I'm thinking it implies Sony reserves a certain, probably similar (I'd even venture, possibly more, given history), amount of GPU for OS.

File under knock me over with a feather...

Some of us assume such things despite internet hyperbole to the contrary...

Exactly what kind of Kinect processing which is what the majority of the GPU time slice seems to be dedicated to, does the PS4 have to do?.

 

[adev]

It doesn't time slice.

They have an OS dedicated graphics queue.

They have the ability to run jobs on specific CUs and the ability to reserve CU memory for specific tasks.

The OS reserves memory which games can't use on several CUs for priority execution.

I'm not going to speculate as to how that would affect game CU utilisation on those CUs with reserved resources.

 

[Rangers]

Exactly what kind of Kinect processing which is what the majority of the GPU time slice seems to be dedicated to, does the PS4 have to do?.

Kinect would be a red herring here. That PS4 has not Kinect !=no GPU OS resources.

Also it has PS eye right? Even if not packed in.

What is your take on what "adev" posted?

Anyways I think it may be OT.

Edit: and adev made a new post above...

 

[Betanumerical]

Kinect would be a red herring here. That PS4 has not Kinect !=no GPU OS resources.

Also it has PS eye right? Even if not packed in.

What is your take on what "adev" posted?

Anyways I think it may be OT.

My understanding was that the PS Eye stuff was all done the CPU. I think it will have a GPU reserve just not as high as he XBONE. What adev is posting seems to be complete rubbish, I will wait for the mods to wakeup.

 

[Ceger]

Exactly what kind of Kinect processing which is what the majority of the GPU time slice seems to be dedicated to, does the PS4 have to do?.

I think that is just an assumption as I'm not sure the majority is for Kinect. The article also stated it is for concurrent apps via snap and the entire OS in general one would assume as you can relegate the running game to it's window on the desktop view and navigate around the UI interface. As the Kinect has plenty of hardware support anyways, I'd imagine that its GPGPU requirements are not necessarily any bigger than the other things the OS needs to be able to do on demand in a smooth and seamless fashion. Any advanced Kinect requirements would most likely use the normal GPU functionality as part of a Kinect focused or supporting game.

Look for the X1 leak video that was put up on Youtube about a month back. I know that while the original was pulled, there were many copies of it out there. That video will demonstrate what I am talking about in case you weren't aware.

 

[Bigus Dickus]

this is complete crap. GPU resources are there to be used, the entire idea of "balance" changes when you change the context. They are execution resources there to do stuff, what ever that might be. Thats the beginning and the end of it, over time dev's will find the optimal use of execution resources for certain tasks with certain compromises.

I don't disagree with anything you said. You need to stop knocking down straw men. I see a lot of that going on in this thread. Of course context changes balance. Each game, maybe even each scene, may be different. PS4 has relatively lots of gpu compute resources. That's a great thing, even if as Sony says the last few CU won't often contribute to significantly increased graphics processing.

i see the people trying to down play the difference is execution resources as the ones with the agenda.

Downplay the differences? Who are you talking about, Sony?

 

[Rangers]

What adev is posting seems to be complete rubbish, I will wait for the mods to wakeup.

I highly doubt it. His posts has the ring of truth.

I am sure PS4 has SOME GPU OS reserve. Silly to think not. 360 did and it had not mandatory Kinect (or Kinect period in early years) or Snap either one.

AFAIK if you push the guide button in a game and want a GUI to pop up swiftly, you need reserved GPU resources.

We have other devs here that could call adev out if they choose. I expect they wont...

 

[Betanumerical]

I highly doubt it. His posts has the ring of truth.

I am sure PS4 has SOME GPU OS reserve. Silly to think not. 360 did and it had not mandatory Kinect (or Kinect period in early years) or Snap either one.

AFAIK if you push the guide button in a game and want a GUI to pop up swiftly, you need reserved GPU resources.

We have other devs here that could call adev out if they choose. I expect they wont...

A ring of truth? the high priority VFX pipe can't do GPGPU we already know that, and how does it make any sense for the OS to reserve parts of the CU register space?. His posts smell of someone who knows something but is just making it up as he goes along.

 

[Rangers]

A ring of truth? the high priority VFX pipe can't do GPGPU we already know that, and how does it make any sense for the OS to reserve parts of the CU register space?. His posts smell of someone who knows something but is just making it up as he goes along.

He says:

They have an OS dedicated graphics queue.

They have the ability to run jobs on specific CUs and the ability to reserve CU memory for specific tasks.

The OS reserves memory which games can't use on several CUs for priority execution.

Seems reasonable to this layman.

 

[patsu]

Am I missing something or the 14+4 NOT came from Sony's Mark Cerny's very own mouth?

It was found in a 2012 Sony slide.

Cerny clarified that the GPU is designed for more than graphics jobs. There are extra ALUs for the devs to use for compute tasks.

 

[Ceger]

Here's that video I referenced above. Anyways, enough OTng this thread. just wanted to share some info as the topic went to X1 GPU utilization.

http://www.youtube.com/watch?v=WD5Bzz6ATR8

 

[Betanumerical]

He says:




Seems reasonable to this layman.

There's a graphics command queue dedicated to VSHELL and it can create high priority GPGPU tasks.

Is completely incorrect.

 

[patsu]

It doesn't time slice.

They have an OS dedicated graphics queue.

They have the ability to run jobs on specific CUs and the ability to reserve CU memory for specific tasks.

The OS reserves memory which games can't use on several CUs for priority execution.

I'm not going to speculate as to how that would affect game CU utilisation on those CUs with reserved resources.

Bahaha, are you saying the OS reserved some CU memory to support the SPUR-like scheduling kernel ?
(It needs to store some states somewhere)

You didn't answer my questions earlier.

Here's one more... when Mark Cerny mentioned that developers may take advantage of PS4 specific features in year 3-4, what exactly does he have in mind ?