[CentOS] Uneven CPU speed with CentOS 4.4 on a Mac Pro

Michael Lampe

Michael.Lampe at iwr.uni-heidelberg.de
Mon Oct 16 14:54:00 UTC 2006


Hi list,

I've recently managed to install CentOS 4.4 on an Apple Mac Pro.
Functionality-wise everything works great, but when trying to benchmark
the system, I don't get stable runtimes, they differ by more than 30%.
For example a benchmark run with our PDE solving code takes between 500
and 800 s on the completely unloaded machine.

Suspicious kernel output (complete output attached):

PCI: Probing PCI hardware (bus 00)
PCI: 0000:00:03.0: class 600 doesn't match header type 01. Ignoring class.
PCI: 0000:00:05.0: class 600 doesn't match header type 01. Ignoring class.
PCI: 0000:00:06.0: class 600 doesn't match header type 01. Ignoring class.
PCI: 0000:00:07.0: class 600 doesn't match header type 01. Ignoring class.

and quite a bunch of

APIC error on CPUx: 60(60).

This is probably due to Apple's not quite perfect BIOS emulation code.

According to /proc/cpuinfo the CPUs don't support any power managment,
cpuspeed isn't running or even configured, and they are always shown as
2.66 GHz, which is correct.

Anyone any idea?

-Michael






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