An isolate is a v8 "virtual machine" running in-process with many other such machines, virtualization is provided by a userspace program
A process is a "virtual machine" running on-host with many other such machines, virtualization is provided by the kernel
A host is a "virtual machine" running on metal with many other such machines, virtualization is provided by the CPU
Metal is a "virtual machine" running on microcode with up to 3 sets of sibling architectural state (did any vendor ever implement 8-way SMT?), virtualization is provided by the silicon
It's turtles all the way down
Even better if the isolate is itself running an emulator, in which case it's also turtles all the way up
Yes, 8-way SMT is available in scale-up POWER 9. But it just merges pairs of 4-way SMT cores instead of adding more threads to each core. The overall number of threads is not affected.
A process is a "virtual machine" running on-host with many other such machines, virtualization is provided by the kernel
A host is a "virtual machine" running on metal with many other such machines, virtualization is provided by the CPU
Metal is a "virtual machine" running on microcode with up to 3 sets of sibling architectural state (did any vendor ever implement 8-way SMT?), virtualization is provided by the silicon
It's turtles all the way down
Even better if the isolate is itself running an emulator, in which case it's also turtles all the way up