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x86 makes decoders way more complex than fixed-width instruction set. In turn this leads to hacks like hyperthreading to allow to make decoders to run in parall
by _0w8t 5y ago
x86 makes decoders way more complex than fixed-width instruction set. In turn this leads to hacks like hyperthreading to allow to make decoders to run in parallel and utilize the whole core. Notice how it is absent from M1 since Apple was able to throw more decoders to single instruction flow and make single-threaded performance great.
- floatboth 5y agoHyperthreading isn't just about decoders, it's about occupying all the units as much as possible. Some Arm (RIP ThunderX2), POWER and SPARC server chips have 4-wide and even 8-wide SMT.
- freemint 5y agoAre you serious? If Intel does that they are just going to have to close a lot of fabs and die as a company.
- imtringued 5y agoMultiprocess python code massively benefits from hyperthreading and it's not bottlenecked by instruction decoding at all. It's bottlenecked by chasing pointers.