How to Check and Fix High CPU Usage on a Linux VPS

High CPU usage can slow down your VPS, cause timeouts, and crash services. Finding the exact process and fixing it quickly is critical for stability.

Step 1: Check Current CPU Usage

Start by viewing real-time CPU usage.

top

Press q to exit. Look for processes with high %CPU.

Step 2: Use htop for a Clearer View

htop provides a more readable interface.

sudo apt update
sudo apt install htop -y
htop

Sort by CPU usage using F6.

Step 3: Identify the Problematic Process

Once you find the process name and PID, inspect it.

ps -fp PID

Replace PID with the actual process ID.

Step 4: Check If the Process Is a Service

Many high CPU issues come from system services.

sudo systemctl status service_name

If the service is misbehaving, logs usually explain why.

Step 5: Analyze CPU Usage History

Check whether CPU spikes are constant or temporary.

uptime

High load average compared to CPU cores indicates overload.

Step 6: Restart or Stop the Process

Restarting often fixes runaway CPU usage.

sudo systemctl restart service_name

Or stop it completely if not required.

sudo kill PID

Step 7: Limit CPU Usage for a Process

Prevent a single process from consuming all CPU.

sudo apt install cpulimit -y
sudo cpulimit -p PID -l 50

This limits the process to 50% CPU usage.

Step 8: Check for Common Causes

High CPU is often caused by web servers, databases, Docker containers, or cron jobs.

crontab -l
docker ps

You may also want to review this related article: How to Fix Services That Fail After Server Reboot

Optional Step: Add Monitoring to Prevent Future Issues

Monitoring helps detect CPU spikes before they cause downtime.

htop
uptime