On Mon, Dec 14, 2020 at 2:54 PM Yasha Karant <[email protected]> wrote:
> I knew persons using the X86 Mac compatibility layer on PPC Macs, and > was told that there was a noticeable performance hit because the > emulator (more or less) functioned as an "inner interpreter" for a > totally different ISA. The same is true between X86-64 and the 64 bit > ARM ISAs (along with other architectural differences). Out of > curiosity, how similar are the Apple Mac ARM CPUs to the CPU used in the > Fujitsu Fugaku HPC machine (A64FX 48C 2.2GHz)? > The big difference is that Apple included, in hardware, the ability to set the memory ordering to the model x86 uses. This way every translated instruction doesn't have to move bytes around, which is why the x86 emulation of the recent Microsoft ARM hardware was so terrible. By all accounts if the code runs in Rosetta 2, it runs very well.
