Quiet the Machine

Early uniprocessor operating systems used disabling interrupts as a synchronization mechanism inside the kernel. Why is this approach insufficient on multiprocessor systems?

Multiprocessor systems use message passing instead of shared memory, making interrupts irrelevant

Disabling interrupts is a privileged instruction that cannot be executed on modern CPUs

Disabling interrupts on one CPU does not prevent another CPU from entering the same critical section concurrently

Disabling interrupts causes all CPUs to halt, creating unacceptable latency