[Beowulf] NMI (Non maskable interrupts)

[Steven Truong]

Dear, all.  We recently bought some dual quadcore AMD Barcelona nodes
with Asus KFSN4-DRE motherboard and installed Rocks Cluster 4.3,
CentOS 5.1 on these machines.

What we found have irked us in terms of the number of NMI generated.

#cat /proc/interrupts
           CPU0       CPU1       CPU2       CPU3       CPU4       CPU5
 CPU6       CPU7
  0:   11468997   11550969   11551029   11550982   11550374   11549932
  11549991   11553108    IO-APIC-edge  timer
  8:          0          0          0          0          0          0
    0          0    IO-APIC-edge  rtc
  9:          0          0          0          0          0          0
    0          0   IO-APIC-level  acpi
177:          0          0          0          0          0          0
    0          0   IO-APIC-level  ohci_hcd
185:          0          0          0          0          0          0
    0          0   IO-APIC-level  ehci_hcd
193:          0     149313        392      38104      36736          0
    1      77870   IO-APIC-level  libata
201:          0          0          0          0          0          0
    0          0   IO-APIC-level  libata
233:   29715082          0          0          0          0          0
    0          0         PCI-MSI  eth0
NMI:     658519     686187     682474     687981     690017     689957
    685692     588203
LOC:   92324693   92324694   92324693   92324692   92324692   92324687
  92324689   92324681
ERR:          0
MIS:          0

# uptime
 11:38:50 up 10 days, 16:27,  1 user,  load average: 7.99, 7.98, 7.99

>From my understanding, NMI is not good since the processors really
have to handle these interrupts right away and these might degrade the
performance of the nodes.  From what I read, NMI are usually generated
by bad hardwares or memory issues and I would like to know how to find
out what causes these NMI...  Could you please point me to the right
direction in finding out more about this?

Thank you.