Adrian (a.delete@this.acm.org) on June 2, 2022 1:47 am wrote:
> Doug S (foo.delete@this.bar.bar) on June 1, 2022 9:50 pm wrote:
> > Peter Lewis (peter.delete@this.notyahoo.com) on June 1, 2022 3:55 pm wrote:
> > > >> I think x86 will eventually be killed by variable length instruction decode, Moore’s law slowing
> > > >> down, availability of software binary translation from x86 to something else and most low-performance
> > > >> software running on top of JavaScript. The x86 instruction sets will eventually have the same market
> > > >> significance as the IBM 360 instruction set. I own Intel stock and I’m not selling because I think
> > > >> it will take more than 20 years for x86 to be displaced from the dominant position it has today.
> > > >
> > > > Why? What are the market forces that you believe will displace
> > > > x86? What do you think will replace it, RISC-V?
> > >
> > > My guess is the higher complexity and higher power consumption
> > > of x86 will eventually allow ARM implementations
> > > to outperform x86 implementations. Apple’s M1 P-cores currently
> > > decode 8 instructions per clock, while Intel’s
> > > Golden Cove cores in Alder Lake and Sapphire Rapids decode
> > > 6 instructions per clock. When ARM implementations
> > > are decoding 32 instructions per clock, it will be very difficult for x86 implementations to keep up.
> > >
> >
> >
> > People have been predicting this ever since the first superscalar RISCs appeared over 30
> > years ago, and it still hasn't happened. A couple years ago people were saying 3/4 wide was
> > the best x86 could manage, now they've beat it. Are you saying where they are now is the
> > limit, or will the goalposts shift again in 5 years when they take the next step wider?
> >
>
>
>
> Using an ISA that requires a more complex decoder, especially when decoding many
> instructions per cycle, is just one of many factors which determine the relationships
> between speed, power consumption, manufacturing cost, design cost.
>
> A disadvantage in ISA can be easily compensated by advantages in manufacturing
> process or just by having more competent designers.
>
>
> The same happens e.g. in a fighting sport. A heavier fighter has an advantage, put
> a more skilled opponent can easily beat him, despite the weight difference.
>
> Nevertheless, when everything else is the same, so the 2 opponents are equally skilled, the heavier
> will win, which is why all fighting sport competitors are separated in weight classes.
>
>
> The same is in CPU design and manufacturing. When everything else would be equal, the
> CPU using an ISA which needs a simpler decoder would be cheaper and/or faster.
>
>
> As long as Intel had other more important advantages, a less efficient ISA did not matter.
>
> Now, when everybody able to do up-to-date CPU design has access to the same manufacturing
> process and they also either might be able to spend similar amounts of money as Intel
> on a CPU design or they might benefit of reduced design costs, e.g. by licensing cores
> or other components, the more efficient ISA begins to matter again.
>
>
>
> Before the last few years, there were no credible chances that x86-64 could be replaced by AArch64, despite
> the claims that were repeated frequently and the various failed attempts to design competitive CPUs.
>
> Now after the incredible difficulties that Intel had in its attempts to remain competitive in semiconductor
> manufacturing, and after a decade during which Intel did not have any clear direction of evolution
> for the evolution of the x86-64 ISA, i.e. the 2022/2023 Intel non-server CPUs are expected to have
> approximately the same ISA as the 2013/2014 Intel CPUs, in contrast with ARM, which evolved from Armv7
> to Armv8 to Armv9, with decent improvements after each ISA revision, the chances of the Intel/AMD
> ISA to be eventually replaced during the next decade have become non-negligible.


Unless and until Microsoft FULLY supports Windows on ARM rather than treating it as a side hobby, and introduces and fully supports both an enterprise license and server version of it, I agree the chance of x86 being replaced by ARM is non-negligible - because it is zero.