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Honest question. Does the ISA, as a language, really matter? Or is it more a by product of who owns the ISA, eg intel sucks, arm is more liberally licensed. I
by asimpletune 6y ago
Honest question. Does the ISA, as a language, really matter? Or is it more a by product of who owns the ISA, eg intel sucks, arm is more liberally licensed.
I used to work at intel, and
no one I knew there thought ISA mattered at all. That’s just a few people though, so I’m curious if people think there’s something better or worse about the different ISAs as a technology in their own right, or if it’s more about the business interests behind them that matters.
- sudosysgen 6y agoIt really doesn't. AMD has essentially the same perf/watt coming in a few months. ISA doesn't change anything nowadays because it all gets decoded into a per-CPU specific actual instruction set anyways.
- spear 6y agoExactly right. With today's transistor budgets, the x86 ISA decoder/translator is just noise. This is not the difference between x86 and ARM -- it's the difference between Intel's team and Apple's (also AMD's). You don't see Qualcomm being competitive even though they also use ARM.
- SomeoneFromCA 6y agoThis is not correct actually. Simpler ISA often requires bigger instruction caches, but consumes less energy because of simpler decoding logic. VLIW theoretically can be super efficient, because it discards decoding stage altogether.
- sudosysgen 6y agoIn theory, yes. This is the case when you have small cores, which is why a lot of GPUs used VLIW. But in practice the whole decoder stage is basically a rounding error because cores got so big.
- headeffects 6y agoWhat does AMD have coming in a few months?
- sudosysgen 6y agoZen 3 on laptops. So instead of Zen 2 on 7nm, laptops should get Zen 3 on 5nm, which is both a 10% uArch clock increase, a 15+% IPC increase, and a die shrink. Basically, laptop chips that should be around 35% faster and use less power.