Dell External OEMR XL R210II Technical Guide - Page 41

Power Saving BIOS Setting OS Control, Maximum Performance

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Dell 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 Fixed PCH switch 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 Fixed PCH Clock The OS is able to configure the system to wake on the RTC alarm. Power Mgmt. Fixed PCH Timer 24-bit power management timer is used. Power Mgmt. Generic PCH Event (PME) 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. PowerEdge R210 Technical Guide 41

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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.