2.4. The irqbalance service

On systems both with and without Non-Uniform Memory Access (NUMA) architecture, the irqbalance service balances interrupts effectively across CPU cores, based on system conditions.

The irqbalance service runs in the background and monitors the CPU load every 10 seconds. The service moves interrupts to other CPU cores when a CPU’s load is too high. As a result, the system performs well and handles load more efficiently.

If irqbalance is not running, usually the CPU core 0 handles most of the interrupts. Even at moderate load, this CPU core can become busy trying to handle the workload of all the hardware in the system. As a consequence, interrupts or interrupt-based work can be missed or delayed. This can result in low network and storage performance, packet loss, and potentially other issues.

On systems with only a single CPU core, the irqbalance service provides no benefit and exits on its own.

By default, the irqbalance service is enabled and running on Red Hat Enterprise Linux. To re-enable the service if you disabled it, enter:

# systemctl enable --now irqbalance