Step‑by‑Step Guide to Diagnose High CPU Usage on Linux

1. Check CPU Usage

Start by inspecting the CPU utilization on a Linux system. Run top or htop in the terminal to see each process’s CPU consumption. If overall usage exceeds 80%, further investigation is warranted.

2. Check System Load

Use the uptime command to view the average load averages. Compare the load values to the number of CPU cores; a load higher than twice the core count typically indicates overload.

3. Inspect Process Resource Usage

Identify which process is consuming excessive resources with pidstat -p <pid> 1. This command prints per‑second statistics for the specified PID, including CPU and memory usage.

4. Trace Problematic Processes

If a high‑resource process is found, trace its system calls using strace -p <pid>. The output shows all system calls and return values, helping locate the root cause.

5. Review System Logs

When the above steps do not reveal the issue, examine log files such as /var/log/messages and /var/log/syslog. Use tail -f /var/log/messages /var/log/syslog to follow new log entries in real time.

6. Identify System Bottlenecks

For deeper performance analysis, employ the perf tool. Running perf top displays functions that consume the most CPU time, allowing you to pinpoint kernel‑level bottlenecks.