AMD Opteron 1218 Wrong CPU Metrics In 6.3

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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:

http://bugs.CentOS.org/view.php?idX21

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%sy50%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.

Thanks.

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