[LAD] cpu spikes

Len Ovens len at ovenwerks.net
Wed Jan 27 15:48:37 UTC 2016

On Wed, 27 Jan 2016, Fokke de Jong wrote:

>>>  16:          0          0          0          0   IO-APIC   16-fasteoi   madifx
> The madifx is my sound card. I have no idea what the fasteoi is though…(anyone ?)

Hmm, I have looked as best I can and it seems fasteoi is an interupt 
translator (best word I could come up with) and it in combination with 
IO-APIC is the same as what some systems show as: IO-APIC-fasteoi I do not 
know if this is kernel version or hardware. however it does appear to be 
tied to the madifx use and so not to worry about.

> I have have 3 PCIe slots

PCIe is a different animal than PCI. The interupts are sent different too. 
Interupt conflicts should not happen.

Do you monitor temperature? (I use Psensor) Which CPU governor do you use?

Looking back at your first post, you are measuring time that your callback 
takes in terms of the wall clock. The fact that it sometimes takes a lot 
longer than it should does indicate that something else is taking some of 
that time.

In another post you suggest that the interupts for 0000:00:17.0 seem to be 
about the right number for every .6 seconds. Have you looked up what 
device that is? ls /sys/bus/pci/devices

in the 0000:00:17.0 directory you can look at the driver which may (or 
not) tell you more about what it is. cat uevent seems to give the most 
readable info. But someone who knows the file system better may be able to 
point to a better way.

Len Ovens

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