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> Now each instruction (increment, load register, occasionally multiply) invokes >10M transistor operations This was the most interesting statement in the slid
by cousin_it 15y ago
> Now each instruction (increment, load register, occasionally multiply) invokes >10M transistor operations
This was the most interesting statement in the slides to me. Can someone explain why so many?
- narag 15y agoHe seems to be writing about floating point operations. Considering instruction pointer logic, buses, cache, branch prediction and all that jazz, not so surprising, but it still seems a lot to me.
- wmf 15y agoAccording to Wikipedia the Alpha 21264 was 6M transistors not counting caches and the Pentium Pro was 5.5M total. 10M doesn't sound far off for today's processors. Since these are some of the earliest out-of-order superscalar processors, they may give an idea of the minimum cost of those features.
- KaeseEs 15y agoA quad core i7 has 1.16 billion transistors, for reference. The question posed was whether each instruction might touch 10 million, or .86%, of these.
- KaeseEs 15y agoThink of how complex merely fetching and decoding an instruction is on a current x86 machine. Now consider how the pipeline, multiple issue, hazard detection and mitigation, and out-of-order execution are implemented. Ten million is probably an underestimate by a fair margin.