meendering stuurde een link naar een Itanium vs Sledgehammer artikel van Sharky Extreme. Nu zul je wellicht denken: weer zo'n pro-Intel bout artikel van Greg Campanaro (SE's hardware editor). Niets is minder waar, want voor dit artikel hebben ze John de Gelas van Ace's Hardware binnen gehaalt, en die weet wel waar-ie over lult . Hier een stukje over de FPU performance van de Sledgehammer, die vanwege de beperkingen van x87 instructieset naar verwachting achter zal blijven bij de FPU prestaties van de Itanium:
The FPU would seem to be the weak link in a 64-bit x86 CPU. Although the Athlon has a strong FPU, it can not compete (clock-for-clock) with the RISC cores of Alpha and SUN and it surely won't be able to compete with Intel's Itanium. The K8 and its siblings would be able to compete with the IA-64 CPU's as long as there are not many IA-64-bit programs. But once IA-64 programs are prevalent, the IA-64 FPU would slaughter the 64-bit x87 FPU. Considering how important FPU has become for desktop CPU's, and how important it has always been for workstations, this is a huge problem.
AMD has, however, anticipated this problem. 64-bit programs will be able to use new RISC-like (three operands) FPU instructions and a new programming model . The new FPU instructions will be able to use a flat floating point register file instead of the old stack based one just like those fast RISC CPU's (SUN, Alpha). In other words, when running 64-bit x86 programs, the double precision FPU performance of the K8 should be on par with the fastest FPU's out there.
But what about single precision (32-bit)? Well, that should be handled by 3DNow!. If developers want the best performance they should go for 3DNow !, which is, thanks to its SIMD capabilities, faster than any x87 FPU will ever be.Provided that AMD can leverage enough software support, the K8 will feature a very powerfull FPU , which will trounce the Athlon's FPU. But there is more.