Energy consumption in modern data centers is a significant concern as it continuously increases cost and environmental impact. Data center providers are searching for ways to offer energy-efficient alternatives to customers, and one of the latest Linux kernel releases is promising.
Many data center administrators are turning to Linux kernel 6.13 to address energy consumption concerns with Linux-based data center devices. This kernel update, released in early 2025, introduces new parameters that administrators can adjust to optimize power utilization and network performance.
This article explores the introduction of adaptive polling in Linux kernel 6.13 and how it reduces energy consumption in data centers. The latter half of the article explains how to deploy and tune Linux kernel 6.13 within multiple distributions.
Linux’s role in data centers
Linux is a critical component of data center deployments. Most web servers run some variation of Linux. Linux’s relative security, lower operational costs and granular control make it appealing for mission-critical on-premises and cloud workloads. Its data management features help ensure compliance, including data sovereignty.
With such extensive deployments, even minor energy consumption adjustments on Linux devices can have a significant impact.
New adaptive polling reduces energy consumption
Linux kernel 6.13 offers power consumption improvements based on changing how the CPU responds to network traffic. Where older kernels caused the CPU to wake each time a packet arrived, the newer hybrid approach modifies the CPU’s behavior based on network traffic. The CPU remains active during high traffic periods and continuously manages network traffic. During times of low traffic, it reverts to the traditional interrupt design.
Linux kernel developers integrated this feature by modifying only about 30 lines of code.
How adaptive polling reduces power consumption
Constant CPU activity consumes a lot of power, especially in high network traffic environments like data centers. Previous Linux kernels relied on an interrupt-driven model. Each arriving network packet interrupted the CPU, which then processed it immediately.
Kernel 6.13 introduces an optional adaptive polling mechanism to the kernel’s network stack. This update lets the kernel switch between interrupt-driven and polling modes based on network traffic levels.
- Interrupt mode. The traditional kernel mode is best for light traffic scenarios. It interrupts the CPU as needed, reducing energy consumption.
- Polling mode. Best for heavy traffic scenarios. It enables the CPU to process network data continuously for improved performance with fewer wakeups.
Adaptive polling includes a new configuration parameter, irq_suspend_timeout. This setting is automatic in kernel 6.13. Most administrators will not need to modify the parameter to start seeing energy consumption benefits.
In fact, administrators are likely to realize two compelling benefits: Reduced energy consumption and improved network performance.
- Reduced energy consumption: Up to 30% less energy consumption, especially in heavy network traffic environments.
- Network performance: Up to 45% improvement in network throughput due to the more efficient network stack during high traffic periods.
These numbers become compelling when considering the number of Linux servers modern data centers deploy.
Potential downsides of adaptive polling
Adaptive polling does not always equate to improvements. Its goal is to balance CPU usage and network efficiency. There are a few situations where it might be a detriment, especially if the irq_suspend_timeout parameter is incorrectly modified.
Negative impacts might include:
- Increased CPU usage during polling, resulting in higher power consumption.
- Reduced efficiency during periods of low network traffic.
- Reduced performance in specialized workloads.
Like any significant kernel modification, administrators responsible for high-performance computing environments should test this feature extensively before implementing it into production. A performance hit or increased power consumption likely means there is a misconfigured setting.
Deploy Linux kernel 6.13
Upgrading to Linux kernel 6.13 or newer is straightforward, although the process varies depending on the distribution.
View the current kernel information by typing:
uname -rAssuming the kernel exists in your distribution’s software repository, use a standard package manager. Check the documentation for your distribution for detailed instructions.
For Debian-based systems, such as Ubuntu and Linux Mint, type:
sudo apt update
sudo apt upgrade
rebootFor Red Hat-based distributions, such as Red Hat Enterprise Linux, Fedora and Rocky Linux or AlmaLinux, type:
sudo dnf update
sudo dnf update kernel
rebootCheck the kernel version using the uname -r command. For additional steps or configurations, refer to the website of your selected distribution.
Performance tuning
The irq_suspend_timeout value controls how long the kernel waits in nanoseconds before reenabling interrupts after switching from polling to interrupt-driven mode. Think carefully before modifying the value. Kernel developers determined the default value, which means it should be well-suited for most uses. You can adjust for advanced performance tuning at /sys/class/net//irq_suspend_timeout.
Test configurations carefully before applying them to production devices. Look for problems with latency-sensitive applications, CPU time and energy consumption. Remember that the benefits and risks of any kernel tuning action will amplify across a data center environment.
Implications for green computing
Linux kernel 6.13 offers broad improvements to green computing initiatives, where small changes can have a significant impact. It alleviates energy concerns while improving network performance without specialized hardware or software. While most data center administrators will upgrade the kernel on their Linux systems as a matter of course, the benefits of adaptive polling justify a proactive look at current deployments.
This simple 30-line modification by kernel developers is a powerful demonstration of Linux’s flexibility and continued development.
