PS3 CPU vs Intel CPUs

[El Greco]

I read the following in Wikipedia (http://en.wikipedia.org/wiki/Playstation_3_cluster):

They say: "Essentially, a single PlayStation 3 performs like a cluster of 30 PCs at the price of only one"

It is also pretty impressive that according to the same page, Playstation 3 clients now provide the bulk of computing power for Folding@Home.

Assuming 30 average Quad Core PCs, how true is the above statement ? Does anybody know when is Intel expected to massively produce processors with more computing power than IBM's Cell ?

[Seren_]

As stated in the Wikipedia article, it might be true for some computations. It does not mean that in any case it is better to use a PS3 core.

You can probably find operations where a single x64 CPU is 30 times quicker than a PS3.

[madurobob]

Does anybody know when is Intel expected to massively produce processors with more computing power than IBM's Cell ?
When IBM licenses them the technology ;)

ETA: looks like 2011 or so? http://en.wikipedia.org/wiki/Larrabee_(GPU)#Comparison_with_the_Cell_Broadband_ Engine

This is specifically related to the broadband engine for mobile devices, but the technology can span platforms, just like Cell.

[Wudang]

If you're interested, some good stuff here
http://www.ibm.com/developerworks/power/cell/
and here
http://www.research.ibm.com/journal/rd51-5.html

[jsiv]

Like Seren_ says, the performance claims relate to certain specific types of single-precision floating point calculations, not general purpose computing (which is what Intel's x86/AMD64 line is all about). Apples and oranges.

It's a bit like how the processor on your graphics card can perform certain operations much faster than your CPU, while being completely unsuited for others. A regular CPU has to be optimized to do everything as fast as possible.

[El Greco]

Ok, what exactly are the PS3's weak points compared to an x86 ? Do we have an idea on what types of benchmarks would an I7 win over a Cell ?

[GreNME]

Ok, what exactly are the PS3's weak points compared to an x86 ? Do we have an idea on what types of benchmarks would an I7 win over a Cell ?

On most desktop operations, I would guess. I couldn't name specifics to you because I'm not completely familiar with the architecture of the chips in the PS3, but as has already been pointed out they aren't made to do the same things, so the comparisons would be imbalanced for most given tests.

It's kind of like a comparison between a dirtbike and a helicopter.

[PixyMisa]

Ok, what exactly are the PS3's weak points compared to an x86 ? Do we have an idea on what types of benchmarks would an I7 win over a Cell ?
Complex branching code, like interpreted languages and databases. As a web server, an i7 would stomp all over a Cell.

The Cell is good at streaming single-precision floating point - about twice as fast as an i7 or Phenom II. It's not good at anything else.

[a_unique_person]

All I know is we went from a four CPU, hyperthreading server running our ERP software to a four CPU system i, iseries, as400 with Power PC5+. Now the Intel server was a few years old, but the CPU load went from about 80% to about 5%.

[GreNME]

Complex branching code, like interpreted languages and databases. As a web server, an i7 would stomp all over a Cell.

The Cell is good at streaming single-precision floating point - about twice as fast as an i7 or Phenom II. It's not good at anything else.

Okay, that makes sense for why it's in the PS3. Basically, it makes a good media appliance processor, yes?

[NewtonTrino]

The cells achilles heal is that each of the SPU's can only access main RAM through DMA transfers. It's really quite a crap architecture for anything other than data going through some sort of transformation that can be streamed. Also keep in mind that the PS3 has more than one type of processor. It has a main Power chip with 2 thread contexts in addition to the SPU's as well as a GPU.

[GodMark2]

Complex branching code, like interpreted languages and databases. As a web server, an i7 would stomp all over a Cell.

The Cell is good at streaming single-precision floating point - about twice as fast as an i7 or Phenom II. It's not good at anything else.

The Cell (and all graphics processors) also excels at one more thing: Matrix Multiplication. It gets used in all sorts of graphics display algorithms. That's one part Folding@Home makes extreme use of.

[PixyMisa]

Okay, that makes sense for why it's in the PS3. Basically, it makes a good media appliance processor, yes?
Yep. As GodMark2 says, it's good at matrix operations (I'd include that within streaming floating point), which covers a very broad range of scientific problems, though the version of the Cell in the PS3 is limited there because its double-precision performance isn't so good. More recent versions of the Cell have much better DP performance.

If you think about it, a lot of what goes on in a modern video game is simulated physics. And if you can do a good job of simulating physics in a game world, you can apply that same number crunching power to the real world.

The way the Cell is structured, though, is that it has one simple CPU (2-issue, in-order) and 8 "SPEs", which are designed to crunch short floating point vectors.

The Core i7 has four complex CPUs (4-issue, out-of-order), each with a short-FP-vector unit. So the Cell has 9 vector units to the i7 or Phenom's 4 (the Cell CPU also has a vector unit), but one simple CPU compared to the i7/Phenom's four complex CPUs.

So for a certain range of tasks, the Cell can deliver twice the performance; for another range of tasks, though, the i7 can deliver four (or more) times the performance.

[GreNME]

Yeah, I kind of knew that's what it meant. I just wanted to put it in a way that was a little more lay-person readable. :)

[Wudang]

No, I got what PixyMisa was saying - they use the Cell to run the Matrix and the reason the i7 is slower is 4 of its processors are out of order.

[El Greco]

So for a certain range of tasks, the Cell can deliver twice the performance

In that case, the quote in my opening post is a gross overstatement, even if we focus on PS3's strong points, right ?