CPU utilization
also: CPU usage, processor utilization
CPU utilization is the percentage of a CPU's processing capacity actually being used to execute tasks, as opposed to idle time. It measures how busy a processor is at any given moment.
CPU utilization expresses how much of a processor's available computational power is being consumed. A value of 100% means the CPU is fully occupied with work; 0% means it's completely idle. Most systems aim for 70–80% utilization to balance performance with headroom for spikes.
On multi-core systems, utilization is tracked per-core and as an overall average. You can monitor it using tools like top, htop, or mpstat. For example, top displays CPU usage in the header row and per-process breakdown below.
High sustained utilization (90%+) indicates the system is CPU-bound and may struggle to handle new tasks; very low utilization suggests the bottleneck lies elsewhere—such as disk I/O or network latency—rather than processing power.