Introduction

High CPU usage in Linux can slow down your system, cause overheating, or make processes unresponsive. Whether you’re using Ubuntu, Debian, CentOS, or any other Linux distribution, identifying and fixing the cause is crucial to maintaining performance. In this guide, we’ll walk you through effective steps to diagnose and resolve high CPU usage in Linux systems.

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1. Check CPU Usage

Start by checking which processes are consuming CPU resources.

top

or use the more user-friendly:

htop

You’ll see real-time CPU usage per process. Identify the processes that are consuming excessive CPU.

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2. Identify the Process Causing the Issue

Once you spot a process with high CPU usage, note its PID (Process ID). You can get detailed info with:
 

ps -p <PID> -o %cpu,%mem,cmd

This helps identify whether it’s a legitimate process or something misbehaving.

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3. Kill or Restart Problematic Processes

If a process is stuck or malfunctioning:

sudo kill -9 <PID>

Alternatively, restart the service:

sudo systemctl restart <service-name>

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4. Check for Background Services

Sometimes, background services or daemons cause high CPU usage. Check active services:

systemctl list-units --type=service --state=running

Disable unnecessary ones:

sudo systemctl disable <service-name>

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5. Investigate System Logs

Logs often reveal the cause of unusual CPU usage:

sudo journalctl -xe

Look for repeated error messages or loops in logs that indicate failing services.

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6. Update Your System

Outdated software or kernels can cause inefficiencies or bugs. Always keep your system updated:

sudo apt update && sudo apt upgrade -y

or for CentOS/RHEL:

sudo yum update -y

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7. Monitor in Real-Time

Use tools like Glances or nmon for continuous system monitoring:

sudo apt install glances
glances

These tools help you proactively detect CPU spikes before they become serious.

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Conclusion

High CPU usage in Linux usually points to a misbehaving process, outdated software, or an inefficient background task. With the tools and steps above, you can pinpoint the problem and bring your system back to optimal performance.

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How to Fix High CPU Usage in Linux (F.A.Q)