Managing CPU and memory usage is essential for maintaining system stability, especially on VPS and servers running multiple applications. Modern Linux distributions use systemd with cgroups v2 to enforce resource limits in a reliable and persistent way. This guide explains the recommended approach using systemd, along with alternative tools for temporary or lightweight control.<\/p>\n
Why Limit CPU and Memory Usage?<\/p>\n
Limiting resource usage helps prevent a single process or service from consuming excessive CPU or RAM. This ensures consistent performance for critical applications, reduces the risk of system slowdowns or crashes, and improves overall server stability, particularly in shared or production environments.<\/p>\n
Method 1: Limit CPU and Memory Using systemd (Recommended)<\/p>\n
On modern Linux systems (Ubuntu 22.04+, AlmaLinux 9, Rocky Linux 9), systemd manages cgroups v2 automatically. Setting limits at the service level is the most reliable and persistent method.<\/p>\n
Note: Ubuntu 20.04 uses cgroups v1 by default. While systemd-based limits still work, full cgroups v2 functionality is available only on Ubuntu 22.04 and later.<\/p>\n
Step 1: Identify the systemd service<\/p>\n
First, determine the service you want to restrict. For example:<\/p>\n
systemctl status nginx<\/pre>\nStep 2: Edit the service override file<\/p>\n
Use the following command to create or edit a systemd override:<\/p>\n
sudo systemctl edit nginx<\/pre>\nStep 3: Set CPU and memory limits<\/p>\n
Add the resource limits under the [Service] section:<\/p>\n
[Service]\r\nMemoryMax=500M\r\nCPUQuota=30%<\/pre>\n
Save and exit the editor.<\/p>\n
Step 4: Reload and apply changes<\/p>\n
Reload systemd and restart the service:<\/p>\n
sudo systemctl daemon-reexec\r\nsudo systemctl restart nginx<\/pre>\nThese limits are persistent across reboots and enforced at the kernel level.<\/p>\n
Method 2: Limit CPU Usage Using cpulimit (Temporary)<\/p>\n
cpulimit restricts CPU usage by pausing and resuming a process. It is useful for short-term control but is not persistent and does not enforce memory limits.<\/p>\n
Install cpulimit<\/p>\n
Ubuntu\/Debian:<\/p>\n
sudo apt install cpulimit<\/pre>\nCentOS\/RHEL (EPEL required):<\/p>\n
sudo yum install epel-release\r\nsudo yum install cpulimit<\/pre>\nApply a CPU limit<\/p>\n
Limit an existing process to 30% CPU:<\/p>\n
sudo cpulimit -p <PID> -l 30<\/pre>\nThis method is suitable for temporary troubleshooting or non-critical workloads.<\/p>\n
Method 3: Adjust CPU Priority Using nice and renice<\/p>\n
The nice and renice commands adjust scheduling priority but do not enforce strict CPU limits. They only influence how often a process gets CPU time.<\/p>\n
Start a process with lower priority:<\/p>\n
nice -n 10 \/path\/to\/program<\/pre>\nChange the priority of a running process:<\/p>\n
sudo renice 15 -p <PID><\/pre>\nThis approach is best used for background or low-priority tasks.<\/p>\n
Verify Resource Usage<\/p>\n
To monitor CPU and memory consumption:<\/p>\n
top<\/pre>\nFor a more user-friendly view:<\/p>\n
sudo apt install htop\r\nhtop<\/pre>\nTo check systemd-applied limits:<\/p>\n
systemctl show nginx | grep -E 'MemoryMax|CPUQuota'<\/pre>\nBest Practices<\/p>\n
Limiting CPU and memory usage is essential for maintaining a stable and efficient Linux server. While tools like cpulimit and nice are useful for temporary control, systemd-based resource limits provide the most reliable and persistent solution on modern Linux systems. By using the appropriate method, administrators can prevent resource abuse and ensure consistent performance across applications.<\/p>\n
Want to manage CPU usage on Windows too? Learn How to Prevent CPU Throttling in Windows<\/a><\/strong><\/em><\/p>\n","protected":false},"excerpt":{"rendered":" Managing CPU and memory usage is essential for maintaining system stability, especially on VPS and servers running multiple applications. Modern Linux distributions use systemd with cgroups v2 to enforce resource…<\/p>\n