IBM Power 595 Technical Overview And Introduction page 78

Figure 2-24 Power management architecture
EnergyScale functions
The IBM EnergyScale functions, and hardware and software requirements are described in
the following list:
Power trending
Power saver mode
Power capping
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IBM Power 595 Technical Overview and Introduction
EnergyScale provides continuous power usage data collection
(monitoring). This enables the administrators with the information to
predict power consumption across their infrastructure and to react to
business and processing needs. For example, an administrator could
adjust server consumption to reduce electrical costs. To collect power
data for the 520, having additional hardware is unnecessary because
EnergyScale collects the information internally.
This mode reduces the voltage and frequency by a fixed percentage.
This percentage is predetermined to be within a safe operating limit
and is not user-configurable. Under current implementation, this is a
14% frequency drop. When CPU utilization is low, power saver mode
has no impact on performance. Power saver mode can reduce the
processor usage up to a 30%. Power saver mode is not supported
during boot or reboot although it is a persistent condition that will be
sustained after the boot when the system starts executing
instructions. Power saver is only supported with 4.0 GHz processors
and faster.
This enforces a user-specified limit on power usage. Power capping
is not a power saving mechanism. It enforces power caps by actually
throttling the one or more processors in the system, degrading
performance significantly. The idea of a power cap is to set