/proc/interrupts: Explanation & Insights

Lists the interrupts that are currently in use on the system

The /proc/interrupts file is a real-time, dynamic file that provides a snapshot of the interrupts happening in your system. An interrupt is a signal sent to the kernel indicating that an event has occurred which needs immediate attention.

Why is /proc/interrupts Important?

Interrupts are crucial for efficient performance of a Linux server. They enable the processor to interact with the hardware in a non-linear manner, improving overall system efficiency. The /proc/interrupts file allows you to monitor these interrupts, helping you diagnose potential issues such as hardware conflicts, bottlenecks or high load.

Understanding /proc/interrupts

Opening the /proc/interrupts file reveals a table. Each row corresponds to an interrupt number (IRQ), and each column represents a CPU in the system. The values in the table represent the number of interrupts that each CPU has processed.

Here is an example of what you might see:

CPU0       CPU1       
0:         45         30   IO-APIC   2-edge      timer
1:         20         50   IO-APIC   1-edge      i8042
NMI:       0          0   Non-maskable interrupts
LOC:       300255     300255   Local timer interrupts

In this example, the timer interrupt (IRQ 0) has been processed 45 times by CPU0 and 30 times by CPU1.

Working with /proc/interrupts

You can view the contents of the /proc/interrupts file using the cat command:

cat /proc/interrupts

For a real-time view, you can use the watch command:

watch -n 1 cat /proc/interrupts

This will refresh the interrupt counts every second.

Troubleshooting with /proc/interrupts

The /proc/interrupts file can be a valuable tool for troubleshooting. For instance, if you notice a specific IRQ with an unusually high count, it could indicate a hardware issue that's causing excessive interrupts. Or if a single CPU is handling a disproportionate number of interrupts, it could suggest a problem with IRQ balancing.

Conclusion

The /proc/interrupts file is a powerful tool for understanding the intricate hardware interactions on your Linux server. It provides valuable insights into the operation of your server and can be an essential part of your troubleshooting arsenal.