> They affect syscall speed because in "conventional" OSes that's the barrier between privileges that's crossed That's not the only case where privilege barrie

> They affect syscall speed because in "conventional" OSes that's the barrier between privileges that's crossed That's not the only case where privilege barriers can be crossed. In x86, that is the most common way for calling into kernel code, but it is not the only way. See io_uring. > Also, IPC does often involve calling to kernel space to execute the IPC? Often. Not always.