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[Kleegamefan]

Most of the PS3 demos we have seen sofar are just running on the dual thread CELL PPE with no assistance from any of the 7 SIMD SPEs ....

I realize each SPE running at 3.2Ghz can do 31B floating point ops/sec and 31B integer ops/sec....

I was wondering how much power the PPE has?

Also, how come SCEI doesn't include/add the power of the PPE when they mention the 218Gflops number in the PS3 specs??

After all, XeCPU is basically using 3 PPEs, which gives us 115B Floating point ops/sec......1/3rd of this 38Gflops, which is quite a chunk of floating point power..

Just curious about this...

 

[Straightballin]

Also, how come SCEI doesn't include the power of the PPE when they mention the 218Gflops number in the PS3 specs??

Im pretty sure they do

 

[pcostabel]

218MFLOPS is for the whole chip:

Each SPE has 4 fpus, doing 2 multiply-add in one cycle (2 flops)

3.2GHz x 2 x 4 = 25.6 MFLOPS per SPE

7 SPE = 179.2 MFLOPS

PPE VMX has again 4 fpus, so that's another 25.6 MFLOPS

Total: 204.8

Where are the missing FLOPS? Nobody knows. We will have to wait until Sony releases full specs for PS3 Cell.

 

[Kleegamefan]

218MFLOPS is for the whole chip:

Each SPE has 4 fpus, doing 2 multiply-add in one cycle (2 flops)

3.2GHz x 2 x 4 = 25.6 MFLOPS per SPE

7 SPE = 179.2 MFLOPS

PPE VMX has again 4 fpus, so that's another 25.6 MFLOPS

Total: 204.8

Where are the missing FLOPS? Nobody knows. We will have to wait until Sony releases full specs for PS3 Cell.

Thank you for that.....what about the XeCPU??

 

[Discordian_taco]

I could be wrong but I believe the PS3 PPE is the same as any one of the 3 x360 cores.

 

[sonycowboy]

218MFLOPS is for the whole chip:

Each SPE has 4 fpus, doing 2 multiply-add in one cycle (2 flops)

3.2GHz x 2 x 4 = 25.6 MFLOPS per SPE

7 SPE = 179.2 MFLOPS

PPE VMX has again 4 fpus, so that's another 25.6 MFLOPS

Total: 204.8

Where are the missing FLOPS? Nobody knows. We will have to wait until Sony releases full specs for PS3 Cell.

The number I've seen quite a few people throw around is:

The CELL GFLOPS number of PS3 should be:

PPE: 3.2 GHz*1 VMX*4D VMX FMAC + 3.2 GHz *1 FPU*2D Paired-single FMAC
=3.2 GHz *1*8 FLOPs + 3.2 GHz*1*3 FLOPs
=25.6 GFLOPS + 12.8 GFLOPS

SPE: 3.2 GHz*7 SPEs*4D SPE FMAC
=3.2 GHz*7*8 FLOPs
=179.2 GFLOPS

PPE + SPEs = 25.6 + 12.8 + 179.2 = 217.6 GFLOPS

 

[pcostabel]

Each XeCPU core is basically a PPE, so

3.2 x 4 x 2 x 3 = 76.8

Microsoft claims 115.2. Again it's not clear where the missing flops are. One hypothesis is that the FPU can also issue a Multiply and add, that will be two additional flops, giving

3.2 x 2 x 3 = 19.2

additional flops, totaling 96 MFLOP for XeCPU and 211.2 for Cell. Still slighlty off.

There is a thread at Beyond3D about this:

http://www.beyond3d.com/forum/showthread.php?t=23089&page=1&pp=40

 

[Excelion]

I could be wrong but I believe the PS3 PPE is the same as any one of the 3 x360 cores.

I'm pretty sure this is correct.

 

[Kleegamefan]

Each XeCPU core is basically a PPE, so

3.2 x 4 x 2 x 3 = 76.8

Microsoft claims 115.2. Again it's not clear where the missing flops are. One hypothesis is that the FPU can also issue a Multiply and add, that will be two additional flops, giving

3.2 x 2 x 3 = 19.2

additional flops, totaling 96 MFLOP for XeCPU and 211.2 for Cell. Still slighlty off.

There is a thread at Beyond3D about this:

http://www.beyond3d.com/forum/showthread.php?t=23089&page=1&pp=40

In that thread, both DeanoC and Fafalada (both PLAYSTATION 3 developers) say the 204.8 GFLOPs is off....


I am also curious how MS gets 115Gflops.....I always thought it was actually ~84Gflops :/