SPEC CPU2006 Platform Settings for IBM Systems

Operating System Tuning Parameters

Zone Reclaim:
Zone reclaim allows the reclaiming of pages from a zone if the number of free pages falls below a watermark even if other zones still have enough pages available. Reclaiming a page can be more beneficial than taking the performance penalties that are associated with allocating a page on a remote zone, especially for NUMA machines.

Firmware / BIOS / Microcode Settings

Operating Mode Selections: (Default="Efficiency -Favor Performance")
The average customer doesn't know the best way to set each individual power/performance feature for their specific environment. Because of this, a menu option is provided that can help a customer optimize the system for things such as minimum power usage/acoustic levels, maximum efficiency, Energy Star optimization, or maximum performance.
Enabling the CPU States causes the CPU to enter a low-power mode when the CPU is idle.
C1 Enhanced Mode:
Enabling C1E (C1 enhanced) state saves power by halting CPU cores that are idle.
Turbo Mode:
Enabling turbo mode can boost the overall CPU performance when all CPU cores are not being fully utilized.
Power/Performance Bias:
Power/Performance bias determines how aggressively the CPU will be power managed and placed into turbo. With Platform Controlled, the system controls the setting. Selecting OS Controlled allows the operating system to control it.
Per Core P-state:
When per-core P-states are enabled, each physical CPU core can operate at separate frequencies. If disabled, all cores in a package will operate at the highest resolved frequency of all active threads.
Turbo Limits:
The maximum turbo frequency can be restricted with turbo limiting to a frequency that is between the maximum turbo frequency and the rated frequency for the CPU installed.
Energy Efficient Turbo:
When energy efficient turbo is enabled, the CPU’s optimal turbo frequency will be tuned dynamically based on CPU utilization.
Uncore Frequency Scaling:
When enabled, the CPU uncore will dynamically change speed based on the workload.
MONITOR/MWAIT instructions are used to engage C-states.
COD Preference:
COD (cluster-on-die) splits the cores/caches into two halves. This improves performance for some applications. Setting the COD preference to Enable does not guarantee that COD will always be enabled. COD is only enabled if the current hardware configuration allows it.Note, COD takes precedence over early snoop.
Early Snoop Preference:
Early snoop may increase performance for some workloads.