RE: spurious 8259A interrupt

From: Guennadi Liakhovetski
Date: Mon Mar 22 2004 - 16:18:20 EST


On Mon, 22 Mar 2004, Maciej W. Rozycki wrote:

> Do you really get "spurious 8259A interrupt" messages for the local APIC
> timer??? They don't ever leave the unit bound to the processor -- it has
> to be something else. What is your contents of /proc/interrupts?

Ok, here's exactly, what I see:
1) during start-up 1 message
spurious 8259A interrupt: IRQ7.
2) at run-time ERR: count increases - sometimes several per
second, sometimes it remains constant for some time.
3) No more "spurious" messages
4) I saw definitely situations, when between 2 /proc/interrupts snapshots
the sum of all (except the timer) interrupts was smaller, than the number
of errors, e.g.

CPU0 (2nd shot)
0: 36557 37638 +1081 XT-PIC timer
1: 59 65 +6 XT-PIC i8042
2: 0 0 XT-PIC cascade
5: 0 0 XT-PIC VIA686A
8: 3 3 XT-PIC rtc
9: 0 0 XT-PIC acpi, uhci_hcd, uhci_hcd
10: 0 0 XT-PIC eth0
12: 84 84 XT-PIC i8042
14: 1910 1918 +8 XT-PIC ide0
15: 1 1 XT-PIC ide1
NMI: 18 18
LOC: 36460 37541 +1081
ERR: 36 57 +21

ide0 + i8042 (keyboard) = 14, whereas errors increased by 21. So, if you
are right, than Alan's wrong (or my understanding of his statement), and
those spurious interrupts occur not only after real ones, or, one real
interrupt can produce several spurious ones.

Thanks
Guennadi
---
Guennadi Liakhovetski


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