AMD: Sea Islands R1100 (8*** series) Speculation/ Rumour Thread

[gkar1]

From the PS4 reveal
http://www.scei.co.jp/corporate/release/pdf/130221a.pdf

The Graphics Processing Unit (GPU) has been enhanced in a number of ways, principally to allow for easier use of the GPU for general purpose computing (GPGPU) such as physics simulation

Is it safe to assume that we will be seeing a form of this tech in future PC products? if so how soon and are these enhancement part of GCN's evolution in the PC space.

 

[rpg.314]

With shared memory, you don't have to worry about coherency. This is a big win for many-core systems where the overhead of enforcing coherency adds up. Also, you don't have to take a cache miss when you first read from it, which an ordinary cache would require, even though it's actually being used as scratch memory. Indeed, many CPUs also have special instructions that operate on the cache as an incoherent scratch pad, though they still have to deal with cache misses since the scratch memory could be evicted at any time. Having shared memory in the programming model allows the programmer to actually take advantage of this without resorting to an ungodly mess of intrinsics.

Those who are in a position to use shared memory can use it without paying for coherence. Those who can't still get the full benefits of cache. Look at how nv is able to configure blocks of SRAM as cache/shared memory.

I am advocating doing that for registers, shared memory and caches. Like LRB.

 

[rpg.314]

From the PS4 reveal
http://www.scei.co.jp/corporate/release/pdf/130221a.pdf


Is it safe to assume that we will be seeing a form of this tech in future PC products? if so how soon and are these enhancement part of GCN's evolution in the PC space.

Depends on how useful Sony's additions are. Cell was supposed to be awesome as well.

 

[DavidGraham]

Ok so Sony confirmed what we already knew , a Jaguar CPU , and 1.84TF AMD GPU , it could be a clocked down HD 7870 , or a clocked up HD 7850 , what do you guys think it is?

 

[Dave Baumann]

Neither.

 

[Ninjaprime]

Its a SoC, and its huge so I'm guessing its 20 CUs with 2 dead ones for yield reasons. Probably a custom design based on Trinity's GPU side.

 

[3dilettante]

Trinity's GPU doesn't fit my conception of a next-generation PC GPU. It's a VLIW4 design, and I think some of the rumors (incoherently) point out features that are more consistent with GCN.

 

[DavidGraham]

Well it should be GCN , that way it is more consistent with the PC world (something Sony was proud to brag about) and it will be state of the art too .

Neither.

It has to be close to something !

 

[gkar1]

Probably a custom design based on Trinity's GPU side.

Incorrect. It's 18 GCN CUs

 

[DavidGraham]

Incorrect. It's 18 GCN CUs

So more like an HD 7860 chip , right ?

 

[OpenGL guy]

But even in the best case, the load ties up a register, and takes up extra bandwidth besides.

Extra bandwidth where? And of course a load takes up a register, where would you store the result?!

Also, effective prefetching is hard, especially when you have to cover 100s of cycles latency.

What prefetching are you referring to?

Why eat the cost if you don't actually need the coherency, which is often the case for inner loops? With a true L1 cache, writes eventually have to be flushed to main memory, and reads have to initially come from main memory, which is quite a waste if it's really a local scratchpad.

None of this makes a bit of sense to me.

 

[AlexV]

Well it should be GCN , that way it is more consistent with the PC world (something Sony was proud to brag about) and it will be state of the art too .

It has to be close to something !

Do you have something against mobile variants? Seems closest to that. Perhaps something Solar. 800MHz-ish by the looks of it. Also, I do wonder how many ALUs the highest-end Kabini will lump on its GPU...

 

[bearmoo]

Is it safe to assume that we will be seeing a form of this tech in future PC products? if so how soon and are these enhancement part of GCN's evolution in the PC space.

The name is Kaveri, APU, end of the year according to roadmap.

 

[gkar1]

The name is Kaveri, APU, end of the year according to roadmap.

Did some research and I'm pretty sure you meant to day Kabini. Kaveri is still based on steamroller cores, unless something changed.

 

[Homeles]

The graphics cores are supposedly next-gen.

 

[jimbo75]

The PS4 thread has some info near the bottom of this page - http://forum.beyond3d.com/showthread.php?t=63108&page=24

Some interesting stuff there. AMD "next gen" (I wonder which next gen they mean ) GPU "18 CUs free to dedicate to graphics or compute efforts as devs like".

 

[3dilettante]

The formerly Sea Islands ISA document mentioned an enhancement to the command queues for an upcoming device.
I don't know whether something like this could be found in an upcoming console, but it sounds like it would be welcomed.

 

[Alexko]

Did some research and I'm pretty sure you meant to day Kabini. Kaveri is still based on steamroller cores, unless something changed.

Bearmoo was referring to the HSA features, I believe. That said, Kabini may very well have the same features, but it's not clear, at least not from this roadmap.

 

[Dave Baumann]

http://blogs.amd.com/fusion/2013/02/21/amd/

As the blog elaborates, the Sony solution is a Semi-custom APU (delivered by the Semi-Custom BU, in fact). Solutions coming through this route are not necessarily cookie cutter from current (or future) solutions, but obviously take from the IP sets we have available.

 

[Alexko]

http://blogs.amd.com/fusion/2013/02/21/amd/

As the blog elaborates, the Sony solution is a Semi-custom APU (delivered by the Semi-Custom BU, in fact). Solutions coming through this route are not necessarily cookie cutter from current (or future) solutions, but obviously take from the IP sets we have available.

Is it strictly speaking an APU, or an SoC? I.e. does it include features traditionally associated with a southbridge?