Article ID: 2207548 - View products that this article applies to.
Today’s modern processors enable scaling of performance and power based on the current activity on the system. The different performance states are dynamically managed by Windows in conjunction with hardware and platform firmware to respond to varying workload requirements. . The 3 default power plans exposed by Windows provide varying tradeoffs of performance vs. power consumption. For example, if the High Performance power plan is selected, Windows places the system in the highest performance state and disables the dynamic scaling of performance in response to varying workload levels. Therefore, special care should be taken before setting the power plan to High Performance as this can increase power consumption unnecessarily when the system is underutilized.
This issue may occur if the Power Options settings are set to Balanced. By default, Windows Server 2008 R2 sets the Balanced (recommended) power plan, which enables energy conservation by scaling the processor performance based on current CPU utilization
To work around the performance degradation issue, you can switch to the High Performance power plan. However, as mentioned previously, this will disable dynamic performance scaling on the platform. Depending on the environment, if the platform is always under a heavy load, then this is a viable solution. In most cases, however, the workload varies throughout the day and thus it is recommended to leave the power plan set to Balanced and evaluate the proper settings within the Balanced power plan for processor power management as described in the Processor Power Management in Windows 7 and Windows Server 2008 R2 paper located here:
Processors change between performance states (“P-states”) very quickly to match supply to demand, delivering performance where necessary and saving power when possible. If your server has specific high-performance or minimum-power-consumption requirements, you might consider configuring the Minimum or Maximum Processor Performance State parameter. The values for both the Minimum and Maximum Processor Performance State parameters are expressed as a percentage of maximum processor frequency, with a value in the range 0 – 100. If your server requires low latency, invariant frequency, or high performance, you might not want the processors switching to lower-performance states.
(http://go.microsoft.com/fwlink/?LinkId=151500)for other considerations.
Article ID: 2207548 - Last Review: August 20, 2010 - Revision: 3.0
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