SPEC CPU2006 Platform Settings for Lenovo 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.

• "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 may increase depending on the workload that is running.
• 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.

C-States:

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.

Hyper-Threading:

Enabling Hyper-Threading let operating system addresses two virtual or logical cores for a physical presented core. Workloads can be shared between virtual or logical cores when possible. The main function of hyper-threading is to increase the number of independent instructions in the pipeline for using the processor resources more efficiently.

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:

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.

Patrol Scrub:

Patrol Scrub is a memory RAS feature which runs a background memory scrub against all DIMMs. Can negatively impact performance.

Fan Speed:

Chassis Managment Module (CMM) allows the fan speed to be set manually.

Maximum OS Cstate:

Maximum processor Cstates can be set manually in the operating system using processor.max_cstate=n, where n is a valid Cstate value.

DCU Streamer Prefetcher:

DCU streamer prefetcher is an L1 data cache prefetcher. Lightly threaded applications and some benchmarks can benefit from having the DCU streamer prefetcher enabled. Default setting is Enable.