Does the PS3's Cell processor use 8 or 9 cores?

[jako]

Sorry guy to re-open an old subject but this guy at GDC 2007 that develops tools for the PS3 talks about 9 cores on the PS3. For me the thing was clear: the PS3 only uses 8 cores.

But this guys has a window running in the background of the screen that tells him how the SPUs work, and he talks about 9 cores..... I'm lost.

Can someone clarify this please ?

http://www.gametrailers.com/gamepage.php?id=2185

[Applefiend]

9 cores in a Cell processor (1 PPE, 8 SPUs)
1 is redundant to increase yields
1 is grabbed by the OS
Leaving 7.

But if you look at a Cell chip, count the cores:

http://embedded.eecs.berkeley.edu/mescal/maw/CellDiePhoto.jpg
You got 9 in your PS3, ya just can't use them all.

[ddaryl]

i thought it was 7 spe's available minus one for the OS

leaving 6 SPE's to be used and 1 core

[PUNK em 733]

i thought it was 7 spe's available minus one for the OS

leaving 6 SPE's to be used and 1 core


You are correct.

[VG Aficionado]

cpiasminc said a few months ago that it wasn't set in stone that the OS reserved SPE would be exclusively used by the OS, and that there might be a chance it could be used partially for game purposes. Things may have changed since then, or maybe I'm just guessing a bit here about game purposes.

[F089/H]

VG is correct.or partially so..I thought a year or so back that there was a set RAM for the OS,but the OS's SPE could be used if needed.

[Sephiroth_VII]

Yeah, but I think it would be easy to lower the RAM usage.

Anyway, the PS3 has 7 SPE's an done PPE. Remember, they're not the same thing. One of the SPE's is disabled in order to improve yields, and another one is reserved for the OS, leaving 6 SPE's and one PPE.

[Nameless]

It has always been reported that the PS3 had 1 PPE and 7 SPEs... (8 cores man)

[Segitz]

Neither is correct, to be "overly" correct.

The SPEs are not cores but units.

The PS3 has 1 PPE (core) and 7 SPEs (units)

[indiekid4]

My brain just exploded!

[jako]

so nothing is clear guys

[rpgamer_2k5]

Neither is correct, to be "overly" correct.

The SPEs are not cores but units.

The PS3 has 1 PPE (core) and 7 SPEs (units) No an SPE is a core. They are processors. They are RISC processors /w 256kb instruction, local store (vs. cache), unified register capable of both general and floating-point ops so they're definitely processors not just of the POWER line. ;)

[stuart_r]

And The PPE is dual Issue so that can be counted as sort of two ;-)

[rpgamer_2k5]

And The PPE is dual Issue so that can be counted as sort of two ;-) You meant dual threaded? The PPE will be viewed as two cores on software. I am pointing this out because the SPEs also feature dual issue pipelines. ;)

[cpiasminc]

cpiasminc said a few months ago that it wasn't set in stone that the OS reserved SPE would be exclusively used by the OS, and that there might be a chance it could be used partially for game purposes. Things may have changed since then, or maybe I'm just guessing a bit here about game purposes.
I have a feeling that was in regards to something else -- talk about an additional "on-demand" grabbed SPE, which sounded highly suspect in the first place. Then again, it's not as though I can peer right into Sony's codebase, but AFAIK, using all the seven active SPEs is not an impossibility in various debugging modes. I never use anything else because I don't work on anything game-specific, so I run things in minimal setups that isolate my area.

You meant dual threaded? The PPE will be viewed as two cores on software. I am pointing this out because the SPEs also feature dual issue pipelines.
Now I'm left picturing how history would have looked if issue window width became the number of logical CPUs. All of a sudden, the 486 would be a dual-processor device, and the 32-bit Athlon would be 9 CPUs.

[jako]

I don't get averything you say Cp.
Is the eight's SPU disabled or is it actually working on the PS3 ?

[stuart_r]

I think that the PPE working in a same way as the P4 hyper-threading so not a true dual-core :-S

[cpiasminc]

I don't get averything you say Cp.
Is the eight's SPU disabled or is it actually working on the PS3 ?
Edited the post. The eighth is disabled in all cases. I was referring to the notion that one would always be taken up by the OS or than the OS would intermittently take up a second.

I think that the PPE working in a same way as the P4 hyper-threading so not a true dual-core :-S
Well, it's SMT, yes. It's not really implemented the same way as P4 hyperthreads, but on the surface, they're the same. Hence why an OS may look upon the PPE as 2 *logical* CPUs, but it is definitely not 2 *physical* CPUs. You'll find a lot of articles even among reputable press outlets by completely oblivious fools who seem to think that a dual-core P4 has 4 CPU cores because each one is Hyperthreaded so it shows up as 4 logical CPUs (and apparently back it up with the marketing name "Core 2 Duo" as if it is implying a "duo" of "2 cores").

[section]

Core2Duo scam was actually new info for me. Thanks for clearing that up :)

[cpiasminc]

I don't know that I'd say "scam" since it's not as though Intel was behind it. It was just a natural result of having technology-illiterate people writing technology articles -- which is pretty much common throughout the non-tech-press, and somewhat present even within technology periodicals. People confuse computer-literate (i.e. "I know how to use Windows") with knowing something about the underlying technology.

I still laugh every time I read an article saying that optical interconnects will finally allow us to route signals at the speed of light. I wonder what computers were doing all this time.

[stuart_r]

core 2 duo has got two core with a shared cache ;-)

[Smokey]

a core2duo is a 2 core chip aint it? what dumb arse would think it was 4?
a good chip i must say, shits on P4 & PD

[GodMachine_Iridius_Dio]

The Core 2 Quad is a quad-core setup, but still retains the "2" for basically no reason. It's possible someone mistook the Core 2 Quad info to mean the Core 2s were all by default, quad-core.

Now on the Cores vs Units front... It's all in the semantics. Each one of the SPEs is a pretty capable processor in its own right, and a fairly complete one, too, so it should be referred to as a core, or a co-processor... They're not an FPU, only, though there is a misconception that that is all they're capable of. An FPU (Floating Point Unit) IS a unit - That's all it does, and without a processor behind it somewhere, it does nothing - It is a part without a whole. An SPE could work on its own to some degree, even without the PPE, and in fact they do already - they have some autonomy.

Oh, and on topic - The CELL is comprised of nine cores, total. One PPE (Think an orchestrator), which is a PowerPC derivative, and eight SPEs, which account for the vast majority of the CELLs power. For the PS3 iteration, one SPE is offline (because it increases acceptable yields, and lowers price) and a second SPE is reserved by the OS, leaving six SPEs for physics, AI, geometry setup/culling, whatever, and the PPE to orchestrate it all, and to some extent, join in. So seven active, usable cores, and an eighth active, but reserved for XMB.


Dio

[Nameless]

^ The whole units argument is bullshit if you ask me it's just simply FUD tactics...

[Rai]

The Core 2 Quad is a quad-core setup, but still retains the "2" for basically no reason. It's possible someone mistook the Core 2 Quad info to mean the Core 2s were all by default, quad-core.

Now on the Cores vs Units front... It's all in the semantics. Each one of the SPEs is a pretty capable processor in its own right, and a fairly complete one, too, so it should be referred to as a core, or a co-processor... They're not an FPU, only, though there is a misconception that that is all they're capable of. An FPU (Floating Point Unit) IS a unit - That's all it does, and without a processor behind it somewhere, it does nothing - It is a part without a whole. An SPE could work on its own to some degree, even without the PPE, and in fact they do already - they have some autonomy.

Oh, and on topic - The CELL is comprised of nine cores, total. One PPE (Think an orchestrator), which is a PowerPC derivative, and eight SPEs, which account for the vast majority of the CELLs power. For the PS3 iteration, one SPE is offline (because it increases acceptable yields, and lowers price) and a second SPE is reserved by the OS, leaving six SPEs for physics, AI, geometry setup/culling, whatever, and the PPE to orchestrate it all, and to some extent, join in. So seven active, usable cores, and an eighth active, but reserved for XMB.


Dio

I learned something today!

[cpiasminc]

The Core 2 Quad is a quad-core setup, but still retains the "2" for basically no reason. It's possible someone mistook the Core 2 Quad info to mean the Core 2s were all by default, quad-core.
That's not likely because most all of the articles to which I refer were before Core 2 Quads were even announced or even that Intel had a quad-core variant in the works. There were some such examples right around the time Core2 Duos hit the market (but before any advertisements would be seen) and the only people who'd seen them were the press.

I still think it was just that someone opened up task manager and saw 4 graphs because Hyperthreading was enabled and said "hey, it has 4 processors!"

[Smokey]

I still think it was just that someone opened up task manager and saw 4 graphs and said "hey, it has 4 processors!"
shit mines a dud, i open up Task Manager & there is only 2 Graphs my core2duo is defective lol :(

[GodMachine_Iridius_Dio]

That's not likely because most all of the articles to which I refer were before Core 2 Quads were even announced or even that Intel had a quad-core variant in the works. There were some such examples right around the time Core2 Duos hit the market (but before any advertisements would be seen) and the only people who'd seen them were the press.

I still think it was just that someone opened up task manager and saw 4 graphs because Hyperthreading was enabled and said "hey, it has 4 processors!"

That is a definite possibility, too, though I've already encountered the latter more than once... Scares me sometimes. :look: