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Intel's 8 MB Itantium 2 processor should NOT be compared to AMD x86 processors because of the extreme differences in the instruction set. The code density for an Itanium is much lower than x86, and consequently it makes a lot more sense to have exquisite and huge cache systems. The whole architecture is so different, it's just not an apples to apples comparison.
Larger caches are not necessarily better. Generally the hit rate will go up, but they are also slower. So, blindly increasing the memory size, because silicon is smaller due to this new technology, would be a bad idea at some point where the diminishing returns of increased size intersect the cost in terms of extra wait states.
It might make for an interesting third level cache though. This way they wouldn't have to slow down the L2 and still get the benefit. Of course, there would be duplication from the L1 and L2 in the L3, so you wouldn't gain the same hit rate as the same size L2 cache would, unless AMD did another exclusive arrangement where the L3 gets fed not from main memory reads, but from L2 discards. I doubt, with all the penallties this entails, AMD would do it, but it can't be completely ruled out.
Larger caches are not necessarily better. Generally the hit rate will go up, but they are also slower. So, blindly increasing the memory size, because silicon is smaller due to this new technology, would be a bad idea at some point where the diminishing returns of increased size intersect the cost in terms of extra wait states.
It might make for an interesting third level cache though. This way they wouldn't have to slow down the L2 and still get the benefit. Of course, there would be duplication from the L1 and L2 in the L3, so you wouldn't gain the same hit rate as the same size L2 cache would, unless AMD did another exclusive arrangement where the L3 gets fed not from main memory reads, but from L2 discards. I doubt, with all the penallties this entails, AMD would do it, but it can't be completely ruled out.
[Posted by: TA152H | Date: 01/19/06 12:58:43 PM]
