Você pode adicionar todas as colunas, exceto id (ocioso), wa (io wait) e st (roubada) para obter a carga da CPU.
Você encontrará a maioria das colunas que significam na página de manual top :
us, user : time running un-niced user processes
sy, system : time running kernel processes
ni, nice : time running niced user processes
wa, IO-wait : time waiting for I/O completion
hi : time spent servicing hardware interrupts
si : time spent servicing software interrupts
st : time stolen from this vm by the hypervisor