How to Check Linux CPU Usage or Utilization? (5 Ways)

Is your Linux server sluggish? Are you wondering why your web applications aren’t performing as expected? Understanding CPU usage and monitoring system performance is a must for every Linux administrator and developer.

In this comprehensive guide, we’ll explore the world of Linux CPU monitoring, from basic command-line tools to advanced monitoring solutions.

Whether you’re managing a high-traffic web server, troubleshooting performance issues, or simply wanting to optimize your system’s resources, this guide will equip you with the knowledge and tools you need.

Let’s start by understanding what CPU usage really means in Linux and how to monitor it effectively using various tools and techniques. By the end of this guide, you’ll have a solid grasp of monitoring, analyzing, and tracking your Linux system’s CPU performance.

Let’s dive right in!

What Causes High CPU Utilization?

If you have been running your server for a long time, several services might be running on it. Resource-intensive tasks like video encoding, database operations, or complex calculations can temporarily spike CPU usage in normal operations. However, when high utilization persists, it often means underlying issues that need attention.

One of the most common culprits is poorly optimized code or applications that create infinite loops, memory leaks, or inefficient database queries. Web applications, particularly those running PHP or Python processes, can consume excessive CPU resources if they’re not properly configured or handling too many concurrent requests.

Content management systems such as WordPress might also strain the CPU when plugins or themes are poorly coded or when caching isn’t properly implemented.

Malicious activities can also significantly increase CPU usage. Cryptojacking malware, which hijacks system resources to mine cryptocurrency, is an increasingly common cause of high CPU utilization. Similarly, DDoS attacks or brute-force attempts can flood servers with requests, forcing the CPU to process an overwhelming amount of traffic.

Sometimes, normal maintenance tasks can lead to temporary CPU spikes. Activities like system backups, virus scans, or package updates typically demand more processing power. However, scheduling these tasks during off-peak hours and properly configuring their resource usage can help minimize their impact on system performance.

Suggested read: Best 9 htop Alternatives for Linux, Mac & Windows in 2024 

How to Check High CPU Utilization on Linux?

There are several ways to track CPU usage on your Linux system. Let’s look at a few of the most common methods.

Method 1: Check CPU Usage with the ‘top’ Command

The top command is one of the most fundamental and widely used tools for real-time system monitoring in Linux. It provides a dynamic view of system performance, showing processes sorted by CPU usage, memory consumption, and other resources. You can run it on your computer by executing the following command in your shell:

top

By default, the top updates every 3 seconds and displays essential information such as load averages, task statistics, and CPU states. Users can interact with the display using keyboard shortcuts, including ‘P’ to sort by CPU usage, ‘M’ for memory usage, and ‘k’ to kill processes directly from the interface.

Suggested read: How to Check Running Processes in Linux Using ps, top, htop, and atop Commands 

Method 2: Monitor CPU Usage with the RunCloud Server Monitoring

RunCloud has a built-in server monitoring functionality that provides a user-friendly, visual approach to tracking CPU utilization. You can view it by simply navigating to the “Monitoring” section of your server settings in the RunCloud dashboard.

The dashboard displays historical CPU usage patterns through intuitive graphs, making it easier to identify trends and anomalies. You can also configure alerts for when CPU usage exceeds defined thresholds, and it provides detailed metrics about individual processes and system resources.

Unlike command-line tools, RunCloud’s monitoring solution retains historical data and provides insights without requiring constant terminal access.

In Linux systems, CPU load represents the average number of processes that are either currently executing or waiting for system resources (CPU, disk I/O, etc.) over a specific time period. Unlike CPU usage percentage, which shows immediate processor utilization, the load average gives you a broader view of system demand over time.

A load average of 1.0 on a single-core system means the CPU is exactly at capacity, while on a quad-core system, a load of 4.0 would represent full capacity. When the load average exceeds the number of CPU cores, it indicates that processes are competing for resources and may need to wait their turn, potentially causing system slowdown.

For example, if a quad-core system shows a load average of 8.0, it means the system is overloaded with twice as many processes as it can handle efficiently, leading to degraded performance.

Suggested read: How to Find Most Used Disk Space Directories and Files in Linux 

Method 3: Monitor CPU Usage with the ‘mpstat’ Command

The mpstat command is part of the sysstat package, and provides CPU statistics for each available processor. This tool is particularly valuable for multi-core systems as it shows per-processor utilization, including user time, system time, idle time, and I/O wait time. You can view your CPU usage statistics by running the following command:

mpstat

System administrators can use options like mpstat -P ALL 2 5 to display statistics for all processors, updating every 2 seconds for 5 iterations, helping identify potential CPU core imbalances.

Suggested read: What are Linux Logs? What Are They & How To Use Them 

Method 4: Use the ‘sar’ Command to Check CPU Usage

The System Activity Reporter (sar) command is a powerful tool for collecting, reporting, and storing system activity information. It can display historical CPU performance data and create detailed reports about system resource usage. The sar command can show CPU utilization data from the current day or from stored system activity files, which makes it invaluable for analyzing performance trends over time.

You can execute the following command to see the CPU usage history on your computer:

sar

In the above example, we can see that each row provides a snapshot of the CPU utilization metrics in 10-minute increments. If you want to customize the output, then you can pass the appropriate flags as the input. For example, sar -u 2 5 shows CPU usage updated every 2 seconds for 5 iterations.

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Method 5: Check CPU Usage with the ‘iostat’ Command

The iostat command provides CPU statistics and input/output statistics for devices and partitions. While it is primarily known for I/O monitoring, it also offers CPU reporting capabilities, which include breakdowns of user time, system time, idle time, and I/O wait time.

You can run the following command to view your CPU usage activity:

iostat

This command is particularly useful when investigating whether high CPU usage is related to disk I/O operations, and you can customize the output of this command according to your needs: options like iostat -c focus specifically on CPU statistics, while iostat -x provides extended statistics.

Suggested read: Using Dynatrace to Monitor RunCloud Servers 

Method 6: Monitor CPU Usage with the ‘vmstat’ Command

The Virtual Memory Statistics (vmstat) command offers a concise view of system performance, including CPU usage, memory, swap space, and I/O statistics. It’s especially useful for identifying bottlenecks affecting CPU performance, such as memory constraints or excessive swapping. You can use this command by executing the following code snippet in your terminal:

vmstat

You can also use some additional command-line arguments to modify its behavior. For example, running vmstat with a delay value (e.g., vmstat 2) provides continuous monitoring and shows how CPU usage changes over time. Its compact output format makes it ideal for quick system health checks and monitoring trends in real time.

Suggested read: How To Monitor Your Web App’s RAM & CPU Usage with Netdata

Wrapping Up

Keeping your server running smoothly is essential for your business, but let’s be honest: traditional server management can be a real headache.

Sifting through complex command-line tools and interpreting raw data isn’t everyone’s cup of tea, and thankfully, it doesn’t have to be. Whether you prefer a quick glance at system performance or a deep dive into specific metrics, there’s a monitoring solution that fits your skill level and needs.

Tools such as top provide a real-time snapshot of your server’s activity for quick checks and on-the-fly monitoring. Need more granular information? Specialized commands like mpstat (for CPU), SAR (for system activity), iostat (for disk I/O), and vmstat (for virtual memory) offer detailed insights, perfect for troubleshooting performance bottlenecks and optimizing your server configuration.

However, juggling these individual commands and analyzing their output can still be time-consuming.

If you’re looking for a more streamlined and user-friendly approach, especially for long-term tracking and analysis, RunCloud offers a powerful alternative.

RunCloud simplifies server management by providing an intuitive dashboard with clear visualizations of key performance indicators. This allows you to easily identify trends, spot potential issues before they escalate, and keep your server running at peak performance – without needing to be a Linux expert.

Learn more & get started with RunCloud.

FAQs on Linux CPU Usage