Boot time scales inversely by the number of CPUs
This can be checked by comparing the boot time (context switch and syscall heavy), when setting QEMU's -smp
to 1, 4, or 16.
The global context switch lock, combined with every processor being preempted exactly at the same time (the BSP sends out IPIs when there are PIT ticks), and that the context is locked numerous times for each syscall, might be the primary causes of this slowdown.