Work out cpu utilisation instantly with clear inputs, formula shown and shareable results.
CPU busy is user plus system time; I/O wait is idle time where at least one process is blocked on disk, so it indicates a storage bottleneck rather than CPU load. High system time relative to user time points at syscall, interrupt or context-switch overhead. Converting the percentage into core equivalents makes headroom concrete.
CPU breakdown
busy = user + system; idle = 100 - busy - I/O wait; cores busy = busy x cores / 100
No. It means the CPU has nothing to do because processes are blocked on storage. Adding CPUs will not help; faster disks or fewer synchronous reads will.
Heavy syscall rates, network interrupt processing, page faults and lock contention in the kernel. Small-packet network traffic and inefficient I/O patterns are common causes.