These are scheduled independently, can run on any CPU, can even run concurrently (none of that is true of hardware interrupt handlers).

If long or complex processing needs to be done, these tasks are deferred using a mechanism call softirqs. Since these can happen very frequently, and since they essentially block the current CPU while they are running, kernel hardware interrupt handlers are written to be as fast and simple as possible. ) when they need to signal something to the CPU (data has arrived, for example). Hardware interrupts are generated by hardware devices (network cards, keyboard controller, external timer, hardware sensors.

Hi is the time spent processing hardware interrupts. St: steal time - % CPU time in involuntary wait by virtual cpu while hypervisor is servicing another processor (or) % CPU time stolen from a virtual machine Si: software irq (or) % CPU time spent servicing/handling software interrupts Hi: hardware irq (or) % CPU time spent servicing/handling hardware interrupts Wa: io wait cpu time (or) % CPU time spent in wait (on disk) Id: idle cpu time (or) % CPU time spent idle Ni: user nice cpu time (or) % CPU time spent on low priority processes

Sy: system cpu time (or) % CPU time spent in kernel space us: user cpu time (or) % CPU time spent in user space This information is not in the man pages. I listed all of us, sy, ni, etc, because it could help others searching for the same. st - they say it's the 'CPU time in involuntary wait by the virtual CPU while hypervisor is servicing another processor (or) % CPU time stolen from a virtual machine'.īut what does it actually mean? Can someone be more clear?.

si - what does servicing software interrupts mean?.

hi - what does servicing hardware interrupts mean?.

While I know the definitions of each of them (far below), I don't understand what these tasks exactly mean. When I issue top in Linux, I get a result similar to this:

Ubuntu show cpu usage