[gwahorton]

In the generation after the one to come, I'd certainly expect at least one vendor to provide hardware assistance for transactional memory and garbage collection in the style of Azul's Vega, to allow efficient code to be written in a nicer language than C++; I think the most plausible candidate is Cray's Chapel. I'd also expect graphics to move into software. That will require a CPU roughly like Tilera's: a mesh of many small, power-efficient cores, with Larrabee-like 512-bit vector units that can scatter/gather. Stacked DRAMs should allow at least a byte of bandwidth per flop.

[TheChefO]

Originally Posted by liolio

I wonder if production capacity could be the answer. One can only reserve that many wafers as there is also a strong pressure on bleeding edge process capacity production.

Thing is along with Yields predictions they may consider the max size for chips. If the chip is to big they that there is no way that they will match projected production figures and so sales goals.

In early life of the system I wonder to which extend capacity production is as much of a concern as price reduction.

Looking forward the pressure on bleeding edge process has grown since 2005/6 thanks to the high demand for mobile products. This trend is going nowhere anytime soon.

That might be an explanation for the noise about MS producing "something" both at GF and IBM.

We may take the problem the in the 'wrong direction", we consider the price of the chip based on yields and size without any regard for wafers availability.
Manufacturers may do the other way looks at production capacity in wafer, then try to match they production goals out of the wafers available and their budget.

Most likely it's a blend of both approaches but that's still different for the approach here where performances and cost is the only factors. Production capacity has to be a strong concern and it's truer now than in 2005/6.

May be in 2005 MS found that the sweet spot was ~175 sq.mm chips (both xenon and xenos are in this ballpark) not only because that's what they need in perfs pov but that could have been the further they are willing to go from a production capacity pov.
Again I believe that it's a blend of both, arbitrations are done between perfs, price and production capacity.

We should not let production capacity out of our speculations, no manufacturers will launch a product if for example they are certain that production won't exceed 4 millions the first year for example. No matter how good the product is they need to grow an significant user base fast.

If we looked at the ps360 both claimed production capacity to be a constrain at some point, that's with 175 sq.mm chips. Now taking in account diminishing yields with bigger chips and less chips per wafer with bigger chip... I believe any one can come to its own conclusion or continue to ignore quiet some evidence like for me my idea of a big SoC (+300 sq.mm) may not be workable for a mass production pov

Good point WRT manufacturing capability.

I'd add a note here though:

MS had manufacturing issues for the first 6 months, but it's not clear that chip production was the issue (though it wouldn't be surprising as final silicone wasn't available until a few months prior to launch). Sony had issues with BR diodes, again, I'm not sure chip manufacturing was the bottleneck.

One other thing, MS was around 170mm2 per chip, but Sony was around 250mm2 per chip. As I said above, I don't recall Sony having an issue manufacturing chips.

I'm sure both Sony and MS would like to have issues with producing enough chips to meet demand, but that may not be the case. Especially if people in general are so ho hum on cutting edge graphics as people seem to suggest.

Either way, I don't think a ~250mm2 would be an issue for mass production on 28nm. Especially if neither one is focusing on 2012. If we're looking at 2013, I don't think either Sony nor MS would have a second thought about producing >250mm2 chips on 28nm.

[east of eastside]

Going to ask a question a little bit out of the mold of typical discussion..

Can some one specify (in single precision FLOPS) what floating point ability should a next-gen console CPU be targeting..? and maybe put that answer along with an explanation in the context of the rest of the hardware, thanks.

[TheChefO]

Originally Posted by east of eastside

Going to ask a question a little bit out of the mold of typical discussion..

Can some one specify (in single precision FLOPS) what floating point ability should a next-gen console CPU be targeting..? and maybe put that answer along with an explanation in the context of the rest of the hardware, thanks.

I'm sure one of the devs here could provide a more specific answer, but I'd say in general, not to expect much improvement on the CPU side. Reason being is that for many calculation intensive cases, a GPGPU could provide much more perf/mm than a CPU and for cases where CPU calcs aren't necessary, the GPU budget will be put to good use in producing better graphics which are an easier sell than a more realistic cloth simulation or better AI algorithm.

Essentially, invest more in the graphics side while ensuring that the graphics side is also more flexible will be the design manifesto.

What this means for the cpu is anyone's guess.

For me it means the performance importance is lessened and thus usability concerns are higher priority. This means things like backwards compatibility, programmer familiarity, codebase-compatibility, and reduced R&D costs. In my mind, this translates to scaled CPU's of the existing architectures.

For MS, likely this means a simple doubling upgrade of Xenon (6 core, 12 thread, 2mb cache, and improved VMX).

For Sony, this is a bit trickier as the things Cell does well, GPGPU also does well, thus doubling Cell may not be the most efficient use of the die budget. I'd expect a 4 PPE, and 6 SPE Cell variant for compatibility and performance.

The Flops that either CPU would end up with is mostly irrelevant as both machines would be reliant more on the GPGPU for their Flop prowess and bragging rights.

[east of eastside]

Originally Posted by TheChefO

I'm sure one of the devs here could provide a more specific answer, but I'd say in general, not to expect much improvement on the CPU side. Reason being is that for many calculation intensive cases, a GPGPU could provide much more perf/mm than a CPU and for cases where CPU calcs aren't necessary, the GPU budget will be put to good use in producing better graphics which are an easier sell than a more realistic cloth simulation or better AI algorithm.

Essentially, invest more in the graphics side while ensuring that the graphics side is also more flexible will be the design manifesto.

What this means for the cpu is anyone's guess.

For me it means the performance importance is lessened and thus usability concerns are higher priority. This means things like backwards compatibility, programmer familiarity, codebase-compatibility, and reduced R&D costs. In my mind, this translates to scaled CPU's of the existing architectures.

For MS, likely this means a simple doubling upgrade of Xenon (6 core, 12 thread, 2mb cache, and improved VMX).

For Sony, this is a bit trickier as the things Cell does well, GPGPU also does well, thus doubling Cell may not be the most efficient use of the die budget. I'd expect a 4 PPE, and 6 SPE Cell variant for compatibility and performance.

The Flops that either CPU would end up with is mostly irrelevant as both machines would be reliant more on the GPGPU for their Flop prowess and bragging rights.

thanks, I appreciate that excellent response and explanation.

For Sony, this is a bit trickier as the things Cell does well, GPGPU also does well, thus doubling Cell may not be the most efficient use of the die budget. I'd expect a 4 PPE, and 6 SPE Cell variant for compatibility and performance.

This was actually behind my interest in the question spurred by the recent Forbes article that AMD was the graphics supplier for Sony's next-generation console. (Charlie Demerjian of Semiaccurate.com who has been behind recent next-gen rumors reaffirmed the validity of the Forbes claim, stating that he has know AMD is behind Sony's console for over a year and would 'spill more beans' soon, for what that's worth..)

I was thinking that Sony might forgo backwards compatibility (seeing as how it's switching from Nvidia to AMD, anyways?) and might go for something simpler and more efficient in the CPU department - like 4 or 6 PowerA2 cores, or other suitable Power core solution, and stay away from Cell entirely if there is significant cost, die and thermal budget gains to be gained by doing so?

Things may not work this way in the real world, but I wouldn't doubt AMD would not want to have anything to do with Cell on several levels.. If this chip is an SoC then adding Cell is going to complicate it significantly. For one, how would manufacturing of a Cell based SoC work? Global Foundries has never touched the Cell processor.. Future die shrinks will require more complicated redesigns as well, owing to the complexity of Cell. Lastly, this might be my own interpretation, but I think as a matter of pride AMD wouldn't want to combine its tech with Cell, it's really contrary to its vision of heterogeneous and GPGPU computing.

In any case, it's my feeling that Cell is done in consoles if anyone wants to give that some thought and expand upon it..

[upnorthsox]

Originally Posted by east of eastside

Going to ask a question a little bit out of the mold of typical discussion..

Can some one specify (in single precision FLOPS) what floating point ability should a next-gen console CPU be targeting..? and maybe put that answer along with an explanation in the context of the rest of the hardware, thanks.

Well starting with MS, a trio of 7th gen Power cores would be a good bet. That'd be 12 OoO threads coming to around 105 gflops (but that may be DP). Adding vmx128 should bump the theoretical up and there's the possibility that it could include vmx256 (which is rumored to be coming with power8). I guess you could just double Xenon flops which would put it at around 230 gflops which sounds realistic.

As for Sony, IMO they'll match MS thread for thread so I'd expect a similar trio of 4 thread cores along with a similar 230 gflops. Then it's a question of including spe's for BC. They could just include an array of 6-8 spe's but that may be more work than you'd expect. The other option would be to include a cluster of 4 spe's with each core (effectively giving you a trio of cutdown Cell's). That'd be alot less work and leave you with a little monster coming in at around 550 gflops.

[TheChefO]

Originally Posted by east of eastside

I was thinking that Sony might forgo backwards compatibility (seeing as how it's switching from Nvidia to AMD, anyways?) and might go for something simpler and more efficient in the CPU department - like 4 or 6 PowerA2 cores, or other suitable Power core solution, and stay away from Cell entirely if there is significant cost, die and thermal budget gains to be gained by doing so?

I look at the intended use case and come to a very different conclusion.

If the CPU performance is no longer key in getting overall performance up, then the choice of which cpu becomes less important. This being the case, the investments by all involved in Cell would lead me to believe this would be the best architecture to choose.

As I said, there are BC issues from the consumers side, but there are also libraries which developers have built, and years of experience in designing software for Cell. Granted, many complaints were lodged against Cell along the way, but solutions to many those problems were found.

Thus the Cell architecture in and of itself isn't a performance prohibitor in the way it once was at the outset of the generation. But in an effort to make Developer's lives easier, I'd suggest bumping up the PPE count to 4 (8 threads), with VMX units and also leave the 6 SPE units on board for Backwards Compatibility of existing software while also providing for an additional workforce for many other tasks going forward that PS3 devs have found use for this gen.

Those 6 SPE's would hardly be sitting idle when running new ps4 games. The could be used for sound, physics, post processing effects, decompression, procedural generation, or whatever else developers might find a use for.

For Developers that either don't want to bother learning Cell if they haven't already, or that don't like coding for SPE's, they can simply use them for sound, and focus on the 4 core 8 thread PPE for the rest of their code.



If the idea behind these consoles is to become more service oriented, one good way to go about that is servicing the existing software libraries that consumers already have (to be used or not, it is still the right gesture in presenting a "platform" as IOS and others have already done).

As long as the architecture isn't holding the machine back in a significant way, I see no reason for them to dump Cell. And with further emphasis on the GPU end and away from the CPU end, I'd say whatever possible edge may be found in a known alternate architecture is irrelevant.

What is relevant is getting new consumers onboard. Having a CPU that is 10-20% faster per mm2 will not negate the loss of compatibility to a significant portion of online software purchases.



For the GPU, if indeed they are turning to AMD, they can surely license or pay a royalty for emulating the RSX on future machines. But again, much like the alternate CPU situation, AMD and Nvidia are both very close in performance. Usability should trump a 10-20% edge in performance and with that, I'd say the only reason for them to dump Nvidia would be if Nvidia is being unreasonable in contract negotiations for ps4 GPU designs.

Either way, I'd expect the issue to be resolved and BC to become a standard for both Sony and MS as they are both actively looking to create Platform ecosystems. And one of the keys to doing that is with software compatibility.

[TheChefO]

Originally Posted by upnorthsox

The other option would be to include a cluster of 4 spe's with each core (effectively giving you a trio of cutdown Cell's). That'd be alot less work and leave you with a little monster coming in at around 550 gflops.

Monster indeed!

That would be rather large and potentially cut down on the GPU budget in a significant way (either that or bring the BOM up a good chunk leading to either less profit down the road or higher MSRP).

If having a 4 PPE 6 SPE Cell would prove problematic, I'd think it would be easier for them to literally do a pair of Cell twins.

Having said that, I can't think of a reason they couldn't do a 4PPE 6SPE Cell.

1 PPE is attached to the 6 SPE's just as it is now in Cell, and the trio of PPE's sits next to the 1st PPE. Have a large shared cache for the 4 PPE's and it's a wrap.

I could be wrong on the above, but from what I've seen in other designs it seems quite possible.

[east of eastside]

Originally Posted by upnorthsox

Well starting with MS, a trio of 7th gen Power cores would be a good bet. That'd be 12 OoO threads coming to around 105 gflops (but that may be DP). Adding vmx128 should bump the theoretical up and there's the possibility that it could include vmx256 (which is rumored to be coming with power8). I guess you could just double Xenon flops which would put it at around 230 gflops which sounds realistic.

Is PowerPC A2 a suitable next-gen console core? I just envisioned a similar quad core PPC A2 chip with 2 quad floating point units (as it is equipped in Blue Gene) per core around 204 flops @ 3.2GHZ under 55 watts.

Originally Posted by TheChefO

Thus the Cell architecture in and of itself isn't a performance prohibitor in the way it once was at the outset of the generation. But in an effort to make Developer's lives easier, I'd suggest bumping up the PPE count to 4 (8 threads), with VMX units and also leave the 6 SPE units on board for Backwards Compatibility of existing software while also providing for an additional workforce for many other tasks going forward that PS3 devs have found use for this gen.

Aside from the 6 SPE for compatibility, how many SPE's do the 4 PPE's include? Or are the VMX units taking their place? Just want to understand this concept.. And does this still fit under the cost, die size, and thermal requirements for a GPU dominant console?

[Blazkowicz]

PPC A2 is maybe or probably tuned for lower frequencies, as an Atom or E350 is, so it might not be able to reach > 3GHz.

[east of eastside]

Originally Posted by Blazkowicz

PPC A2 is maybe or probably tuned for lower frequencies, as an Atom or E350 is, so it might not be able to reach > 3GHz.

Yeah, I noticed that..Okay, is there a more appropriate PPC core then?

I guess there is a PPCA2 version that runs at 2.3ghz @ 45nm. Perhaps a 28nm might cross 3ghz?

[Brimstone]

Originally Posted by TheChefO

If the CPU performance is no longer key in getting overall performance up, then the choice of which cpu becomes less important. This being the case, the investments by all involved in Cell would lead me to believe this would be the best architecture to choose.

I think it's a safe bet Sony is going with a 4k Blu-Ray format with the PS4. The H.265 codec will require processing muscle. A CELL v2.0 CPU with plenty of SPE seems likely.

[RedVi]

So you're saying they learnt nothing from this gen? 4k BD drives will delay the console and make it much more expensive while still only allowing for the same cost to be spent on chips (or less), Cell v2.0 will be pretty useless once again for multi-platform developed titles. All I can say if they go for Cell again is that they beef up the PPU's and only double (or something) the amount of SPE's. Say 4 PPU's with OoOE and more cache and 12-16 SPE's. MS will likely go with 4-6 of those same PPU's, if sony were to think one or two was enough, they'd end up at a severe disadvantage.

[Brad Grenz]

4K BD drives are just regular BD drives with software support for a new codec (h.265) and/or additional readable layers. In neither case can the cost be compared to the first mass-produced blue laser diodes the PS3 was using... And Cell 2.0 would be useful in multiplatform games for the same things Cell has been this gen: physics, sound, post processing effects including AA. The codebase is already there. So in fact, what we're talking about is a PS4 with all the advantages the PS3 had, and none of the disadvantages.

[upnorthsox]

Originally Posted by TheChefO

Monster indeed!

That would be rather large and potentially cut down on the GPU budget in a significant way (either that or bring the BOM up a good chunk leading to either less profit down the road or higher MSRP).

If having a 4 PPE 6 SPE Cell would prove problematic, I'd think it would be easier for them to literally do a pair of Cell twins.

Having said that, I can't think of a reason they couldn't do a 4PPE 6SPE Cell.

1 PPE is attached to the 6 SPE's just as it is now in Cell, and the trio of PPE's sits next to the 1st PPE. Have a large shared cache for the 4 PPE's and it's a wrap.

I could be wrong on the above, but from what I've seen in other designs it seems quite possible.

I don't think so, but it depends on L3 edram. A trio of mini-Cells at 32nm would be a little bigger than the current 45nm cell and running in the sub 40W range. That'd be with the standard 1MB per thread of L3 (12MB in total) for the cores. They could always cut that out and go a little smaller or go the opposite and add 1MB per spe for a total of 24MB of L3 edram. It'd depend if they wanted to emphasis the spe's or not, but a cpu slightly larger than the current one is not some kind of budget buster.

[TheChefO]

Originally Posted by east of eastside

Aside from the 6 SPE for compatibility, how many SPE's do the 4 PPE's include? Or are the VMX units taking their place? Just want to understand this concept.. And does this still fit under the cost, die size, and thermal requirements for a GPU dominant console?

Aside from the 6? None. The 6 SPE's would primarily be there for BC sake, while also providing for a number crunching workforce going forward.

The VMX units in the PPE's would be for additional processing power and also for those that have an issue for one reason or another in tapping SPE's.

Essentially allowing for easy porting between xb720 and ps4.

The size of such a chip would be roughly double what a 28nm PS3 Cell would be (roughly 120mm2).
The TDP would be well manageable, roughly the same powerdraw as a current 40nm Cell in PS3.


In conclusion, such a design would be exactly tuned to what would be required for a GPU-centric design.

[TheChefO]

Originally Posted by Brad Grenz

So in fact, what we're talking about is a PS4 with all the advantages the PS3 had, and none of the disadvantages.

This is exactly where I'm looking at this from as well.

Even if we took the exact same Cell as in PS3 and used it in PS4, but bumped the GPU up, there would be significant upswing as the Cell is no longer being forced as a GPU assistant, and as we've said, the code libraries have been built for utilizing Cell.

The familiarity of Devs with Cell is there now. They have the codebases to sample from. They have the best usecases to work with. And with Cell not being tied down to graphics work, it can be free to work on other aspects of the game worlds.

It's truly a win-win.

[TheChefO]

Originally Posted by upnorthsox

I don't think so, but it depends on L3 edram. A trio of mini-Cells at 32nm would be a little bigger than the current 45nm cell and running in the sub 40W range. That'd be with the standard 1MB per thread of L3 (12MB in total) for the cores. They could always cut that out and go a little smaller or go the opposite and add 1MB per spe for a total of 24MB of L3 edram. It'd depend if they wanted to emphasis the spe's or not, but a cpu slightly larger than the current one is not some kind of budget buster.

You're right, it wouldn't be that large.

4 PPE, 12 SPE would be in the neighborhood of ~160mm2.

There would have to be a bit of code rewriting though for existing software to work in this model of 4spe/1ppe.

[Xenus]

Not really from what I gather most code running on Cell runs on a job dispatch system. So it really wouldn't care so much how the SPE's are configured just if one is free or not. There maybe some things that need redone but on a whole it doesn't seem like that much.

[Shifty Geezer]

Originally Posted by Brad Grenz

And Cell 2.0 would be useful in multiplatform games for the same things Cell has been this gen: physics, sound, post processing effects including AA. The codebase is already there. So in fact, what we're talking about is a PS4 with all the advantages the PS3 had, and none of the disadvantages.

I wouldn't look at it like that. The majority of devs didn't get on with Cell this gen, and haven't mastered it nor become fluent with it. Code portability is next to non-existent in real terms from title to title, so you'll have to rewrite code for whatever processor is in PS4. And as a lot of the code will likely be shifted to GPGPU work (even if PS4 had Cell, cross-system development would mean GPGPU focus for XB3 and PC codebases), what you save will likely be negligable.

I could see SPEs being included for BC and maybe for some standard libraries. eg. A Sony engineered audio library to handle all audio seems like it'd be very valuable given bkilian's revealing post on audio consumption. Otherwise the silicon would go unused by most developers, and add cost and complexity to the system design. Sony would be better off with a hardware paltform that'll be easy for them to support their software layers on for the grand Unified Software Experience. Rather than rewriting browsers for every single device, they should have a common hardware aspect (bunch of compiler flags, rather than completely different code bases) that makes the same code very portable and maintainable. Otherwise, keeping all that digital content active across all devices will be a PITA.

The only exception I can see to that is if they create a true Cell 2 that'll see wider adoption than Cell did, which is extremely unlikely. Broadcom is making tiny processors to power media that serve the major functions of Cell's intended power consumers, hence Cell never made it into TVs or STBs or anywhere else. That'd be the same for Cell 2 unless it's very different in some way I can't imagine. Without a true Cell 2, putting 6-8 SPEs on the PS4 CPU would be a difficult choice to make as there's no obvious favour for either side.

[Xenus]

That is what I hate about what the console domain is becoming vs what it used to be. You shouldn't design consoles to be similar for the sake of portability you should design consoles for the best performance given certain factors. If they end up similar so be it but don't design similar consoles for the sake similarity.

[Teasy]

Unfortunately its becoming a necessity with the cost of game development increasing so much.

[Shifty Geezer]

But that era is over I believe. Back in the day, the differences in your hardware made for different experiences. There was reason for them. Now that graphics have consolidated around the DX shader model format, there's nothing to be gained by doing things differently. Unless there's a breakaway alternative like a raytracing console or a voxel console, with custom hardware to enable stuff not doable on other devices, and providing a marketing edge to make the alternative technology workable, there's no real point to it. The future is the selection of games and experiences. It's not as interesting as it used to be, but it's not necessarily bad either. I mean, PCs really are dull compared to the old 8-bit and 16-bit computers + consoles. They're just generic parts mixed-and-matched under the same OS. But what I can do on my PC now is incredible! It's so much more useable as a creative tool for life that it doesn't need to be a hobby in itself. The nerd in me would like to see bizarro hardware the likes of PS2 that would never be seen outside a console but which enabled some amazing things, but the whole-other-human-being in me will just be happy to see good games and smart software, and hope simplified hardware will bring stability and serviceability to the whole experience.

[MrFox]

For sony, 4K comes for free.

The old Cell can already decode two 1080p streams at 40Gbps total. They only need twice that performance to do 4k in H264 (or quad-HD). The drive costs practically nothing today, a firmware update can make the drive read 128GB BDXL discs which is plenty for a full length film at over 100 Gbps (they could spec to 144Gbps mux, for a 4x drive requirement). Any GPU can display quad-HD. HDMI can output quad-HD too. It all comes for free, they'd be stupid not to implement it.

But that's an unimportant feature. I want them to make a CPU/GPGPU combination with the memory bandwidth necessary to have effortless global illumination, and traced soft-shadows. Anything less and they might hold on to the PS3/360 because doubling the CPU and GPU is exactly what Nintendo did with the Wii. I can't see the difference between gamecube and Wii. 2x isn't enough of a jump to start a new generation.

[east of eastside]

I don't think backwards compatibility is worth the investment to support it. Conversely, Sony is forgoing the opportunity to sell Uncharted Collection in 1080p for PS4. Loss of compatibility with PSN titles would be more of a concern to me.