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Dell Dumping Itanium
njcoder writes "In a PC World article it is disclosed and confirmed by Intel that Dell is dropping support for Itanium processors. 'After Advanced Micro Devices demonstrated that 64-bit extensions to the x86 instruction set offered a smoother transition to 64-bit computing, Intel released a version of Xeon with similar technology, and Dell now offers 64-bit Xeon processors across its product line.'" More from the article: "The chip maker has since backed off its original statements about Itanium and is now promoting the chip as a high-performance replacement for reduced instruction set computing (RISC) processors in Unix servers from companies such as Sun Microsystems and IBM. Hewlett-Packard, a co-designer of the processor, has embraced Itanium as the processor of choice for its high-end servers. Fujitsu. and NEC are also among the system vendors that sell servers with the processor." The story is also being reported at Ars Technica.
SGI uses Itanium for their Altix line of products that run Linux. They need Itanuim for its ability to handle hundreds of processors in one system with cc:NUMA, and its huge physical address space for their customers who need several terabytes of RAM in one system.
Isn't everyone dumping Itanium? Why is Dell any different?
Lost at C:>. Found at C.
x86 processors have a fixed amount of decoder logic overhead vs. RISC. The decoders essentially dynamically translate the x86 instructions into more machine-friendly micro-ops which are very RISC-like.
As transistor budgets increase exponentially (thanks to Moore's law), that fixed overhead gets smaller and smaller each generation - to the point that it's insigificant (less than 5% today and getting smaller tomorrow). So in the early 90s you could make a case for more efficient computing with RISC vs. x86, but today it's just so negligable that you don't care. There are also numerous micro-architectural tricks to get around the limited registers and wacky addressing modes.
Couple this with the fact that 99% of all of the world's software is written for x86 and you have a very large inertia to overcome in order to change the ISA.
Why would any software vendor port their application to a new architecture if that architecture is brand new and nobody is using it initially? This is a very expensive and risky task. Let's say that the incentive is increased performance with a new ISA (highly unlikely given that the ISA doesn't matter anymore given the very large transitors budgets). But let's be generous and give it a 50% performance advantage (again - this is fantasy land). Do you spend the 8 months porting, debugging, testing Photoshop? Or do you just wait 8 months for a 50% faster x86 to come out and instead spend that time improving your product as opposed to keeping it the same on a different architecture?
You'd have to be crazy to take that tradeoff. And so, you see what we have today - x86 everywhere.