Proc - Interrupts file

You can check which interrupts are currently in use and what they are used for by looking in the file /proc/interrupts:

cat /proc/interrupts 
 
             CPU0        
    0:    8728810          XT-PIC  timer 
    1:        895          XT-PIC  keyboard 
    2:          0          XT-PIC  cascade 
    3:     531695          XT-PIC  aha152x 
    4:    2014133          XT-PIC  serial 
    5:      44401          XT-PIC  pcnet_cs 
    8:          2          XT-PIC  rtc 
   11:          8          XT-PIC  i82365 
   12:     182918          XT-PIC  PS/2 Mouse 
   13:          1          XT-PIC  fpu 
   14:    1232265          XT-PIC  ide0 
   15:          7          XT-PIC  ide1 
  NMI:          0 

In 2.4.* a couple of lines where added to this file LOC & ERR (this time is the output of a SMP machine):

cat /proc/interrupts 
 
             CPU0       CPU1       
    0:    1243498    1214548    IO-APIC-edge  timer
    1:       8949       8958    IO-APIC-edge  keyboard
    2:          0          0          XT-PIC  cascade
    5:      11286      10161    IO-APIC-edge  soundblaster
    8:          1          0    IO-APIC-edge  rtc
    9:      27422      27407    IO-APIC-edge  3c503
   12:     113645     113873    IO-APIC-edge  PS/2 Mouse
   13:          0          0          XT-PIC  fpu
   14:      22491      24012    IO-APIC-edge  ide0
   15:       2183       2415    IO-APIC-edge  ide1
   17:      30564      30414   IO-APIC-level  eth0
   18:        177        164   IO-APIC-level  bttv
  NMI:    2457961    2457959 
  LOC:    2457882    2457881 
  ERR:       2155

where:

In 2.6.2* /proc/interrupts was expanded again. This time the goal was for /proc/interrupts to display every IRQ vector in use by the system, not just those considered 'most important'. The new vectors are: