Weird system cpu usage

[Daniel Gerzo]

Hello Mike,

Wednesday, March 19, 2008, 9:32:13 PM, you wrote:

>>Also, I believe there was a report from another user who saw similar
>>issues with em(4), and found that disabling MSI fixed the storm in
>>question.  I believe you can disable MSI/MSIX by placing the following
>>in /boot/loader.conf, then reboot:
>>
>>hw.pci.enable_msi="0"
>>hw.pci.enable_msix="0"

> When MSI is enabled, the irq will be a strangely high number.  e.g.

Interesting, I have disabled MSI and MSIX support, but they still share
the same irq. However, I don't know yet if the interrupt storm is
going to be resolved, it needs some time (It always used to take some
time until it has showed up).

> If anything, I found enabling MSI helped matters where I saw strange 
> IRQ issues.  However, not sure if the original poster's hardware 
> supports it.   One thing it does remind me of is some strange IRQ 
> issues I had on an AMD board where a USB setting for "legacy handoff" 
> (something like that) would really slow down the machine with an in 
> inordinate amount of IRQs firing.  I forget if I had to enable it or 
> disable it to fix the problem.  If anything, I would try disabling 
> USB all together if its not being used even though its not figuring 
> in the above really high rate of IRQs.

The USB isn't indeed used, I will think about disabling it, and also
about trying to move around the em(4) NICs to the other slots.
Unfortunately I don't have a physical access to the given maschine.

-- 
Best regards,
 Daniel                            mailto:danger at FreeBSD.org