My Intel Xeon 5500 series-based system seems to run jobs more slowly on a particular CPU compared to running the same jobs on other CPUs, specifically when not all CPUs in the system are active. What causes this and what can I do to work around it?

Issue

• When some CPUs on an Intel Xeon 5500 series-based system running Red Hat Enterprise Linux 5.3 are in the ACPI C3 C-state (sleep state) and others are not, users will see an issue where the CPU in charge of IRQ 0 suffers a performance penalty of 10% or more due to overhead.
• For example, CPU 0 and CPU 8 on a test system take 11.05 seconds to run a test program and a...