timer interrupt (IRQ0) and IRQ4

[wke...@gmail.com]

Hi,
I run cat /proc/interrupts on Feodra 18 x86_64 machine, and I
get these results (after 1 hour the machine is up)

0: 127 0 IO-APIC-edge timer
..
4: 1 1 IO-APIC-edge
...

question 1:
we see 127 timer interrupts on core 1. It seems that these 127 interrupts
occur immediately in boot or in a short while afterwards, as it
seems that they are not progressing. Why do we need at all this timer
(on IRQ0) ? there is an apic timer: cat /proc/interrupts shows that
it is incrementing all the time:
cat /proc/interrpts | grep LOC:
LOC: 288967 289350 Local timer interrupts

question 2:
what is interrupt 4 ? it does not show any description.Also, there is
only 1 interrupt on it (on both cores).

Rgs,
Kevin