De man top
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2c. CPU States The CPU states are shown in the Summary Area. They are always shown as a percentage and are for the time between now and the last refresh. us -- User CPU time The time the CPU has spent running users' processes that are not niced. sy -- System CPU time The time the CPU has spent running the kernel and its pro‐ cesses. ni -- Nice CPU time The time the CPU has spent running users' proccess that have been niced. wa -- iowait Amount of time the CPU has been waiting for I/O to complete. hi -- Hardware IRQ The amount of time the CPU has been servicing hardware inter‐ rupts. si -- Software Interrupts The amount of time the CPU has been servicing software inter‐ rupts. st -- Steal Time The amount of CPU 'stolen' from this virtual machine by the hypervisor for other tasks (such as running another virtual machine).