kipmi-process consuming 90% CPU

[Matt Domsch]

On Tue, Oct 21, 2008 at 08:02:07AM +0200, Kenneth Holter wrote:
> 
>    Hello list.
> 
> 
>    I have a process name "kipmi0" consuming about 90% CPU, and I believe that
>    this process is part of the Dell OpenManage agent.
> 
>    The process' nice-value is 19, so overall it doesn't seem to get too much
>    in the way of other processes. But is this normal, or can this be fixed
>    somehow? What does the kipmi process do anyway?

This is both normal and expected.

kipmi0 is effectively a very fast polling loop. When an IPMI command
has been issued to the controller, kipmi0 polls on completion of that
command, and then retrieves the bytes of the answer.  Unfortunately,
the hardware interface (KCS) has no interrupt one could use to avoid
polling.

You can disable kipmi0 via an ipmi_si module parameter, but I wouldn't
recommend it.  Doing so reduces the speed at which IPMI commands
complete by a factor of 10 or more.  Why, you ask, do you care?
Because OMSA on system startup will take several minutes instead of
several seconds while it retrieves all the sensor status.  Firmware
updates (while rare) slow down from 1.5 minutes to 15+ minutes.  Other
polling to retrieve sensors during runtime (not just system startup)
are likewise much slower.

kipmi0 only runs when there are outstanding IPMI commands issued, and
even then runs at a low CPU priority, so only uses "idle" cycles.
While it appears strange, it's the best we can do with the hardware
interface we've got.  And this is standard across the whole industry,
not just Dell.

Thanks,
Matt

-- 
Matt Domsch
Linux Technology Strategist, Dell Office of the CTO
linux.dell.com & www.dell.com/linux