[CentOS] AMD Opteron 1218 wrong CPU metrics in 6.3

Thu Jul 12 11:03:04 UTC 2012
Vlad K. <vlad at haronmedia.com>

Hello all,

since upgrade to 6.3 (and kernel 2.6.32-279.x) it looks like only one 
core of the AMD Dualcore Opteron 1218 is functional. Reverting to 
previous kernel shows everything working as expected.

I've filed a bug report here after failing to figure out if it is just a 
configuration problem:


I can't find anything on the net that would explain where the problem 
is. /proc/cpuinfo shows two cores, but top and /proc/stat show basically 
one core working:

- top shows cpu0 idle constantly at 0%, and sporadic 100%sy or 50%sy 
50%us, which can't be right
- /proc/stat shows cpu0 idle and iowat at 0
- Munin CPU graph shows 200% available but metrics go only up to 100%
- mpstat -P ALL shows proper %idle for both cores, but still core0 gets 
either 100%sy or 50%sy 50%us sporadically.

I've also got this in the logs, possibly due to BIOS, and I don't know 
if it is related, I've seen it with 6.2 too.

Jul 11 20:44:57 app1 kernel: [Firmware Bug]: powernow-k8: No compatible 
ACPI _PSS objects found.
Jul 11 20:44:57 app1 kernel: [Firmware Bug]: powernow-k8: Try again with 
latest BIOS.

Any ideas what the possible cause could be or what can I do to figure 
this out? It's a rented server so I don't have the ability to toy with 
the BIOS.



.oO V Oo.