Power Management Modes; 10.3.1 Dell Active Power Controller; Power-Saving Bios Setting (Os Control); 10.3.3 Maximum Performance - Dell PowerEdge R310 Technical Manual

Dell

Power Management Modes

10.3

10.3.1 Dell Active Power Controller

The Dell Active Power Controller (DAPC) is a Dell proprietary implementation. DAPC is implemented in
system BIOS and uses hardware level counters, etc. to determine hardware utilization. The BIOS uses this
information to determine when to change the processor's operating frequency. The DAPC is OS independent.
This provides a consistent power management solution regardless of the installed OS.

10.3.2 Power-Saving BIOS Setting (OS Control)

Intel processors support Demand-Based Switching (DBS) which enables the processor to dynamically change
its operating frequency in response to workload changes. The industry-standard implementation of this
power management feature is in the OS. The OS monitors process/thread-level utilization of the processor
and uses processor controls to change the processor's operating frequency. For heavy workloads, the OS will
run the processor at higher frequencies for additional performance. Lighter workloads do not need high
performance, thus the OS will run the processor at lower frequencies.

10.3.3 Maximum Performance

The Maximum Performance Mode disables power management. In this mode, the processor frequency is
statically set to the highest supported frequency.
The power management features are implemented via two categories: fixed or generic. Fixed features use
bits defined in the ACPI specification for specific capabilities. The fixed feature bits give the OS complete
control over the power management of a device since the location of the bits is given to the OS in the FACP
table. Thus, a driver can directly access bits to control a device's power management. Generic features
have defined enable and status bits, but the functionality is not fully visible to the OS. Dell provides ASL
code to handle the details of generic features, allowing the OS to intelligently communicate with system-
specific hardware.
The following table summarizes power management features on this system.
Dell PowerEdge R310 Technical Guide
Table 12.
Wake Up Events
RTC
Power Button
RI#
PME#
KB
MOUSE
USB
WOL
Supported ACPI States
States Can Wake From
S5, OS-S4
S5, OS-S4
Not supported
S5, OS-S4
Not supported
Not supported
Not supported
S5, OS-S4
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