Author: Francois LE COAT (ASte-Genev-Bois-154-1-112-252.w83-199.abo.wanadoo.)
Date: 05-06-2008 01:35
Let's explain ...
Cell multimedia processor is composed with two parts. First a general purpose CPU called *PPE*, and 8 multimedia peripheral processors called *SPE*. In ARAnyM case the code only runs on *PPE* not taking advantage of the "Synergetic Processing Elements" that would dramatically enhance the speed on PlayStation 3.
I personally supervised the port of ARAnyM on PS3 multimedia machine. The main point is simpler than a problem with its code optimization for the peculiar Cell architecture.
No. The point is *PPE* that runs the code is a processor that is binary compatible with the PowerPC processors family. In facts ARAnyM in the case of PlayStation 3 runs on PPC64 (64bits PowerPC) compatible with G3, G4 and G5 processors used so far on Apple computers (until Apple made the transition to Intel recently).
So, the lack of performances you can observe on the PlayStation 3 is exactly the same as what was obtained with the Macintosh before Apple's switch to Intel CPU.
ARAnyM includes a code accelerator (software cache) called "Just In Time compiler" (JITc) specifically written for x86 processors (not x86_64 CPU) that hasn't been ported to PPC (nor PPC64 furthermore) ATM.
ARAnyM takes a great advantage of a software accelerator (data and instruction cache) on x86 processors, that doesn't benefit to Cell embedded on PS3, depending on how far it is developed for PowerPCs (on software).
Maybe one day it will change. This acceleration will both benefit to Mac and PS3, for very identical reasons.
That's my deep wish for the PlayStation 3.
The benchmark I submitted shows relative speedup. One can see that except the case of the EeePC we are close to the power of the Hades 60. Remind it is the faster ATARI clone ever built, based on Motorola 68060. That's my reference.
I hope I make myself understood =)