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.

Disabling Intel Idle Driver:

intel_idle is a Linux cpuidle driver that loads on specific Intel processors replacing the legacy ACPI processor_idle driver. The intel_idle driver uses its built-in logic to control the processor C-state directly, bypassing the BIOS/UEFI settings. The intel_idle driver can be disabled by adding "intel_idle.max_cstate=0" Linux kernel parameter. This will make the BIOS/UEFI C-state settings effective again.

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.

• "Minimal Power" mode strives to minimize the absolute power consumption of the system while it is operating. The tradeoff is that performance may be reduced in this mode depending on the application that is running.
• "Efficiency -Favor Power" mode maximizes the performance/watt efficiency with a bias towards power savings. It provides the best features for reducing power and increasing performance in applications where maximum bus speeds are not critical. It is expected that this will be the favored mode for SPECpower testing. "Efficiency -Favor Power" mode maintains backwards compatibility with systems that included the preset operating modes before Energy Star for servers was released.
• "Efficiency -Favor Performance" mode optimizes the performance/watt efficiency with a bias towards performance. It is the favored mode for Energy Star. Note that this mode is slightly different than "Efficiency -Favor Power" mode. In "Efficiency - Favor Performance" mode, no bus speeds are derated as they are in "Efficiency -Favor Power" mode. "Efficiency -Favor Performance" mode is the default mode.
• "Maximum Performance" mode will maximize the absolute performance of the system without regard for power. In this mode, power consumption is a don't care. Things like fan speed and heat output of the system may increase in addition to power consumption. Efficiency of the system may go down in this mode but the absolute performance can go up depending on the benchmark that is run.
• A fifth setting, "Custom", allows the user to individually modify any of the low-level settings that are preset and unchangeable in any of the other 4 preset modes.

Power C-States:

Enabling the CPU States causes the CPU to enter a low-power mode when the CPU is idle.

Turbo Mode:

Enabling turbo mode can boost the overall CPU performance when all CPU cores are not being fully utilized.

Turbo Boost:

This BIOS option can be set to Power Optimized or Traditional. When Power Optimized is selected, Intel Turbo Boost Technology engages after Performance state P0 is sustained for longer than two seconds. When Traditional is selected, Intel Turbo Boost Technology is engaged even for P0 requests less than two seconds.