Filter
Top Products
Dell
PowerEdge R210 Technical Guide 41
9.3.2 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
Operating System (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.
9.3.3 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.
Table 15. Summary of R210 Power Management Features
Feature
Type
Enable/Status
/Ctrl bit
location
Description
ACPI mode
switch
Fixed
PCH
The OS uses the SCI_EN bit to switch from
legacy mode to ACPI mode.
Sleep states
Fixed
PCH
Supported states: S0(Working), S4-OS
(‘Hibernation’ in W2K), and S5 (Soft-off).
S1 (also called ‘standby’ or ‘suspend’) and S3
are not supported.
Power Button Fixed PCH In ACPI mode, OS has control of the power
button. In non-ACPI mode, SMI handler owns
power button events.
Real-Time
Clock
Fixed
PCH
The OS is able to configure the system to wake
on the RTC alarm.
Power Mgmt.
Timer
Fixed PCH 24-bit power management timer is used.
Power Mgmt.
Event (PME)
Generic PCH Each host bus’s PME# signal is routed to a
separate general-purpose event pin in the
chipset. When a device signals PME#, the system
wakes (if necessary), the OS detects the event,
and a Dell defined ASL routine handles the
event. Wake-on-LAN is one example of a PME.