Hironobu Sakaguchi's opinion of cell and PS3

[3dilettante]

The wording of the quote seems to favor the interpretation that he considers Cell to be seven DSPs and a low-powered CPU.

I think the low-powered jab was aimed squarely at the PPE.

The DSP part was the jab at the SPEs.

 

[archie4oz]

He could be talking mainly about the Ps3's CPU minus the spes, which barely outperformed the Wii's CPU in benchmark tests.

The CPU performs terribly without the spes... well terrible considering it's high clock speed of 3.2ghz.

It uses a PPE core which is stripped down. There isn't a full featured PPC core in the 360 or the ps3.

The only next gen system this time with a fully featured PPC core this time around in the Wii, but it's clocked low... really low.

Uh, the PPE (in both Cell and Waternoose) implement more of the PowerPC ISA than Broadway does...

Out of Order?

Better performance per clock?

The reality is that the PowerPC unit for Nintendo is more complex than the PPE alone.

No it isn't...

 

[The_legend_of_drtre]

Uh, the PPE (in both Cell and Waternoose) implement more of the PowerPC ISA than Broadway does...

That's false.

PPE's are not fully featured PPC's in the same since of say a G5. Notice how theere aren't any G5's on the market that run at 3.2ghz??? Yeah that's because they would run way to hot and cost way too much.

This is the main reason why apple switched to intel. They wanted a a chip that had high clock speeds and ran cool for their new laptops and the g5 coulnd't do that... well not at the speed they wanted.

Apple wanted chips with high clock speeds for their computers because they know that is what the average customer looks at. High numbers. The highest clocked G5 is like 2.7ghz I believe and runs way to hot for their planned laptops.

IBM even offereed Broadway to apple for those laptops but again... the clock speeds weren't high enough.

The reason why the PPE's in the in the 360/ps3 can run so high is because they are missing features from the G5. This is also a reason why the systems must use multiple cores to get their target performance numbers, they don't won't to well on their own.

As was said above, they went with in order to keep the cost down for the 360 as well. Even the original xbox was out of order.

Broadway is a fully featured PPC core with added instructions. Just like Gekko before it.

It is a better CPU clock for clock than the PPE in the 360/ps3 is just clocked way to slow to really be a factor.

Broadway at 729mhz would kill a PPE at the same clock speed.

 

[nAo]

That's false.

PPE's are not fully featured PPC's in the same since of say a G5.

Please enlighten us, what a fully feature PPC core is?

 

[The_legend_of_drtre]

Please enlighten us, what a fully feature PPC core is?

How about a PPC core that has all the features of a G3/G4/G5 which the PPE does not?

 

[Zeross]

That's false.

PPE's are not fully featured PPC's in the same since of say a G5. Notice how theere aren't any G5's on the market that run at 3.2ghz??? Yeah that's because they would run way to hot and cost way too much.

Yeah and there isn't a Core 2 at more than 3GHz while the old P4 could run at more that 3.7GHz, does that mean that Core 2 is not a fully featured x86 ?

 

[The_legend_of_drtre]

Let's talk about the PPE in the ps3:


"Power Processor Element
The PPE is based on the POWER Architecture (a two-way SMT Power 970 architecture compliant core), which is the basis of IBM's line of POWER and PowerPC offerings. The PPE is not intended to perform all primary processing for the system, but rather to act as a controller for the other eight SPEs, which handle most of the computational workload. The PPE will work with conventional operating systems due to its similarity to other 64-bit PowerPC processors, while the SPEs are designed for vectorized floating point code execution. The PPE contains a 32 KiB instruction and a 32 KiB data Level 1 cache and a 512 KiB Level 2 cache. Additionally, IBM has included a VMX (AltiVec) unit in the Cell PPE.[9] The PPE's VMX (AltiVec) unit is fully pipelined for double precision floating point and each SPU can complete two double precision operations per clock cycle, which translates to 6.4 GFLOPS at 3.2 GHz; or eight single precision operations per clock cycle, which translates to 25.6 GFLOPS at 3.2 GHz.[10]"

The PPE in the ps3 is not a G5 class PPC.

Take a look at this:

http://www.geekpatrol.ca/2006/11/playstation-3-performance/

It barely out performes a 1.5ghz G5 and it's 3.2ghz!


And this:

http://games.slashdot.org/comments.pl?sid=138810&cid=11616545

"Apple is going to use this processor in their new machine.
Doubtful. The problem is that though the main CPU is PowerPC-based like current Apple chips, it is stripped down, and the Altivec support will be much lower than in current G5s. Unoptomized, Apple code would run like a G4 on this hardware. They would have to commit to a lot of R&D for their OS to use the additional 8 processors on the chip, and redesign all their tweaked Altivec code. It would not be a simple port. A couple of years to complete, at least."

 

[Zeross]

The PPE in the ps3 is not a G5

This is the only thing true in your posts, the rest is pure non sense. You're mistaking a lot of things, speaking of frequency, features and now performance. The fact that the PPE is not as fast as a G5 clock for clock doesn't make it "less featured" it's a design choice.

 

[The_legend_of_drtre]

This is the only thing true in your posts, the rest is pure non sense. You're mistaking a lot of things, speaking of frequency, features and now performance. The fact that the PPE is not as fast as a G5 clock for clock doesn't make it "less featured" it's a design choice.

Read the links I posted above. It wasn't a design choice... it was a cost choice and it is missing quite a few features from a G5 which is why it doesn't perform on par.


The PPE is a stripped down G5. Since is lacks alot of features of a G5 it can be clocked higher.

 

[Zeross]

Read the links I posted above. It wasn't a design choice... it was a cost choice

A design choice encompass a lot of things you have to take into account : performance is one factor, transistors budget is another, yields etc...

The PPE is a stripped down G5.

It is not based on the G5, the only thing they share is the PPC ISA

Since is lacks alot of features of a G5 it can be clocked higher.

This is just plain illogical : a PowerPC 601 lacks a lot of features of a G5 and it can't be clocked near as high. You should Google for things like pipelining it would help you better grasp some basics of microprocessor architecture.

 

[nAo]

How about a PPC core that has all the features of a G3/G4/G5 which the PPE does not?

You're still really vague, name these features, make a list, otherwise there's really no point in going around telling ppl they're wrong since it seems to me you have your own personal definition of what a fully features ppc core is.
Once you define these things we can have a real discussion, otherwise it's all a big waste of time.

 

[V-G]

Is it just me or has this thread derailed into a debate of semantics?

 

[The_legend_of_drtre]

A design choice encompass a lot of things you have to take into account : performance is one factor, transistors budget is another, yields etc...

It is not based on the G5, the only thing they share is the PPC ISA

This is just plain illogical : a PowerPC 601 lacks a lot of features of a G5 and it can't be clocked near as high. You should Google for things like pipelining it would help you better grasp some basics of microprocessor architecture.

Don't play dumb. The 601 is not based off the 970. The PPE is.

 

[3dilettante]

Don't play dumb. The 601 is not based off the 970. The PPE is.

I don't see much resemblance from the unit counts and pipeline lengths. The cores are vastly different.

Just because they both have VMX units doesn't make them alike.

 

[The_legend_of_drtre]

I don't see much resemblance from the unit counts and pipeline lengths. The cores are vastly different.

Just because they both have VMX units doesn't make them alike.

"Power Processor Element
The PPE is based on the POWER Architecture (a two-way SMT Power 970 architecture compliant core), which is the basis of IBM's line of POWER and PowerPC offerings. The PPE is not intended to perform all primary processing for the system, but rather to act as a controller for the other eight SPEs, which handle most of the computational workload. The PPE will work with conventional operating systems due to its similarity to other 64-bit PowerPC processors, while the SPEs are designed for vectorized floating point code execution. The PPE contains a 32 KiB instruction and a 32 KiB data Level 1 cache and a 512 KiB Level 2 cache. Additionally, IBM has included a VMX (AltiVec) unit in the Cell PPE.[9] The PPE's VMX (AltiVec) unit is fully pipelined for double precision floating point and each SPU can complete two double precision operations per clock cycle, which translates to 6.4 GFLOPS at 3.2 GHz; or eight single precision operations per clock cycle, which translates to 25.6 GFLOPS at 3.2 GHz.[10]
"

 

[3dilettante]

There is a difference between two chips having similar ISA support and saying one core is based on the other.

The PPE has stronger ties to a design IBM created prior to the release of POWER4 and its derivative PPC 970 cores.

 

[The_legend_of_drtre]

There is a difference between two chips having similar ISA support and saying one core is based on the other.

The PPE has stronger ties to a design IBM created prior to the release of POWER4 and its derivative PPC 970 cores.

Oh I see.

 

[Crossbar]

"Power Processor Element
The PPE is based on the POWER Architecture (a two-way SMT Power 970 architecture compliant core), which is the basis of IBM's line of POWER and PowerPC offerings.
"

That mean they share the same instruction set, nothing else.

 

[Shifty Geezer]

"Power Processor Element
The PPE is based on the POWER Architecture (a two-way SMT Power 970 architecture compliant core), which is the basis of IBM's line of POWER and PowerPC offerings. ...

When quoting evidence to back up a statement, you need to include a source, as the source adds or detracts credibility. eg. If what you are quoting is an IBM document on Cell, it has a lot more weight than if what you are quoting is an analysis at ArsTech, or a forum post at GAF, or even something you just made up! We need to be able to check sources to know information provided is trustworthy.

 

[archie4oz]

Oh dear, where do they grow your kind?

That's false.

I'm afraid it's not. Try running any code that makes extensive use of doublewords (chess programs often do) on a Wii and watch the performance tank. Do you wanna know why?

PPE's are not fully featured PPC's in the same since of say a G5. Notice how theere aren't any G5's on the market that run at 3.2ghz??? Yeah that's because they would run way to hot and cost way too much.

Yes it would run hot... The 970 was designed around automated layout, while the PPE leverages more custom layout and has a significantly higher percentage of dynamic circuits.

This is the main reason why apple switched to intel. They wanted a a chip that had high clock speeds and ran cool for their new laptops and the g5 coulnd't do that... well not at the speed they wanted.

Apple wanted chips with high clock speeds for their computers because they know that is what the average customer looks at. High numbers. The highest clocked G5 is like 2.7ghz I believe and runs way to hot for their planned laptops.

The reasons are numerous. It had little to do with "high clock" as you so much postulate. Clock speeds have been pretty much irrelevant as far as Apple goes (in fact they've been marketing around it since before AMD started using PR numbers) as well as Apple's customer base also not being very swayed by clock speeds. Yes the 970 was totally unsuitable for a laptop. However, Apple being Apple I can imagine grew quite tired of funding processor development. It's expensive. Plus they've had a history of screwing over and pissing off their suppliers as well at the slightest roadblock. Intel (and for the record AMD actually has pretty damn good low-power options too) simply had product, and the roadmap that Apple needed to move forward, plus it would save them a bundle (and it certainly wasn't the first time Apple has dallyed with Intel either).

Broadway at 729mhz would kill a PPE at the same clock speed.

Broadway at 729MHz would kill a 970 at the same clock as well in most scalar code mixes (with the probably exception of double-precision maths)

The PPE in the ps3 is not a G5 class PPC.

There's no such class as a G5 class PowerPC... At least amongst those of us who've been programming on PowerPCs over the past decade...

Don't play dumb. The 601 is not based off the 970. The PPE is.

No it isn't, it's completely unrelated...

"Power Processor Element
The PPE is based on the POWER Architecture (a two-way SMT Power 970 architecture compliant core), which is the basis of IBM's line of POWER and PowerPC offerings.

Wow is that SOOOOOOOO wrong...