Pat Stemen Senior Program Manager Windows Platform Architecture Group Microsoft Corporation.
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Transcript of Pat Stemen Senior Program Manager Windows Platform Architecture Group Microsoft Corporation.
Power Optimizations ForWindows PlatformsPat StemenSenior Program ManagerWindows Platform Architecture GroupMicrosoft Corporation
Key Takeaways
Enable system designers to optimize Windows Vista power policy for energy efficiencyProvide guidance on platform design best practices for energy efficiency
Agenda
Energy EfficiencyEvaluating Energy EfficiencyConfiguring Windows Vista Power PolicyOther Windows Vista Power OptimizationsPlatform Design Best Practices
Energy Efficiency Introduction
Energy efficiency enables more than extended mobile PC battery life
Regulatory compliance for desktop and server systemsIncreased density of server deploymentsOperational energy expense reduction
Improving Energy Efficiency
Evaluate system power consumptionConfigure platform hardware and software policies
Trade performance for power savingsExamples
Enable a short monitor blanking timeoutEnable power save mode for 802.11 Wi-Fi adapter
Use energy-efficient hardware componentsInstall energy-efficient preload software
Evaluating Energy Efficiency
Methods to measure mobile PC battery lifeFirst, choose a scenario
Idle, DVD playback, Industry-standard benchmark
Perform run-down tests for first-level validationMeasure full-charge to empty drain duration
Repeat several times and average
Instrumented systems can be used to validate fine-grained changes
E.g., changes in video device / driver power management
Desktop and server power consumptionAverage AC power consumption
Evaluating Energy Efficiency
Indirect indicators of system power consumption
Effective use of deep processor idle statesObserve with Perfmon, PwrTest, or processor vendor utilities
Effective use of processor performance statesSystem should be in lowest performance state when processor utilization is low for maximum power savings
Observe with Perfmon or PwrTest
Default platform timer tick intervalPlatform timer should be at the default 15.6 ms value
Use event logging to see when applications change the timer frequency
Mobile PC Power Consumption
*Example Thin-and-Light Platform, Windows Vista RTM Idle
Display 43%Blanking, Dimming
Graphics
8%Processor 9%Perf, Idle States
Network 4%802.11 Power Save
HDD 5%Spin-down, DIPMChipset 21%
11.5 WAverage Power Consumption
IHV-Specific Technologies
Windows Power Policy
Windows Vista power policy defaults are generalized for multiple platforms and scenarios
“Balanced” power plan by defaultAdaptive behaviors enabled where possibleTimeouts are conservative
System manufacturers may configure policy for aggressive power savings
Help improve mobile PC battery lifeMeet regulatory compliance guidelines
System Idle Timeouts
Save power by turning off components after a period of inactivity
E.g., Turn off the display after 5 minutes without user input
Notable timeoutsDisplay / monitor blanking
Hard disk drive (HDD)
System Sleep, Hibernate
Display Idle Timeout
Turns off the display after a period of user inactivity
Display is ~40% of mobile PC power budget
External displays require 20W -> 100W+
Reduce the display timeout to increase power savingsFriendly Name Turn off the display
Description Specify how long your computer is inactive before the display turns off
GUID 3c0bc021-c8a8-4e07-a973-6b14cbcb2b7e
PowerCfg Alias VIDEOIDLE
Balanced Defaults 20 minutes (AC) 5 minutes (DC)
Sleep Idle TimeoutPlaces the computer to sleep after a period of inactivity
Most systems consume 1-3 W in Sleep
Less for mobile PCs
Application requests for system availability are considered
E.g., System stays on for PVR, music streamingFriendly Name Put the computer to sleep
Description Specify how long your computer is inactive before going to sleep
GUID 29f6c1db-86da-48c5-9fdb-f2b67b1f44da
PowerCfg Alias STANDBYIDLE
Balanced Defaults 60 minutes (AC) 15 minutes (DC)
Hard Disk Idle Timeout
Spins down HDD media after a period of disk read / write inactivity
Power savings varies by disk model
Typically 100-400mW on mobile HDDsFriendly Name Turn off hard disk after
Description Specify how long your hard drive is inactive before the disk turns off
GUID 6738e2c4-e8a5-4a42-b16a-e040e769756e
PowerCfg Alias DISKIDLE
Balanced Defaults 60 minutes (AC) 30 minutes (DC)
Processor Power Management
Detailed configuration in power policy:Min and max range of processor frequency
Parameters that influenceTarget performance state calculation
Idle state promotion/demotion
Care must be taken when tuning processor policies
Tuning must be platform-specific
Attend the processor power management tuning chalk talk
Reference public processor power management paper for more details
Domain Idle AccountingDetermines how the power manager calculates idle for performance states
Only applicable to systems with more than 1 logical processor
When enabled…
Idle time accrued only when all processors in the domain are idle
Favors performance
Windows Vista default
When disabled…
Idle time accrued when any processor in the domain is idle
Favors power savings
Processor will tend to stay in lowest performance state more often with domain idle accounting disabled
Attend SYS-C315 Tuning Processor Power Management
802.11 Power Save ModeChanges the polling rate of the 802.11 wireless adapter
Saves power by periodically turning the radio on / off
Requires a spec-compliant AP implementation
Power savings may be up to 600-700mW with Maximum Power SavingsFriendly Name Power Saving Mode
Description Control the power saving mode of wireless adapters
GUID 12bbebe6-58d6-4636-95bb-3217ef867c1a
PowerCfg Alias n/a
Balanced Defaults
Maximum Performance (AC)
Maximum Performance (DC)
Active State Power Management
Allows PCI Express links to enter low power idle states
Enabled in policy by default in Windows Vista
Requires native OS control of PCI Express features
See References for ASPM paper on WHDCFriendly Name Link State Power Management
Description Specifies the ASPM link policy to use when capable links are idle
GUID ee12f906-d277-404b-b6da-e5fa1a576df5
PowerCfg Alias n/a
Balanced Defaults
Moderate Power Savings (AC)
Maximum Power Savings (DC)
USB Selective Suspend
Selective suspend has large impact on system power consumption
Frequent DMA prevents effective utilization of processor idle states
Inability to use processor idle states may reduce mobile PC battery life by ~30%
USB devices must support selective suspend
Particularly when integrated into mobile platforms
Validate your platform or device is properly using selective suspend
Ensure effective use of processor idle states
USB Selective Suspend
Allows USB devices to suspend when they are idle
Enables the USB scheduler to turn offReduces DMA activity and increases processor idle state utilization
Power policy is global for all USB controllers and devicesFriendly Name USB Selective Suspend Setting
Description Specify whether USB selective suspend is turned on or off
GUID 48e6b7a6-50f5-4782-a5d4-53bb8f07e226
PowerCfg Alias n/a
Balanced Defaults
Disabled (AC) Enabled (DC)
Windows Search And Indexing
Indexing activity integrated into power policy
Controls the level of system indexing activity
Power modes match system power plan defaults
High PerformanceAll items are indexed, system-wide crawls are allowed
BalancedOnly high and normal-priority items are indexed, system-wide crawls are disabled
Power SaverOnly high-priority items are indexed, such as arriving e-mail
Windows Search And Indexing
Friendly Name Power Saving Mode
Description Specify power savings mode for Search and Indexing
GUID c1dd9fd6-ff5b-4270-8ab6-d48f1c40506a
PowerCfg Alias n/a
Balanced Defaults
High Performance (AC) Balanced (DC)
SATA AHCI Link Power Management
Allows SATA links to opportunistically enter low-power modes
Device-Initiated and Host-Initiated (DIPM, HIPM) power management
DIPM disabled by default in Windows VistaAllows lower-power AHCI link states
Limited disk compatibility issues
Requires Microsoft native SATA driver (msahci.sys)Registry Key HKLM\SYSTEM\CurrentControlSet\Services\
msahci\Controller0
Value (Binary) DIPMEnabled , 0x01
Default Disabled
Sleep Power Policies
Friendly Name Required Idleness to Sleep
Description Specify the amount of processor idleness required for the system to automatically sleep
GUID 81cd32e0-7833-44f3-8737-7081f38d1f70
PowerCfg Alias
n/a
Balanced Defaults
80% (AC) 80% (DC)
Sleep Idle Detection Threshold
Configures the amount of processor idle required for the system to sleep
Set to 0% to allow power manager to ignore CPU utilization when determining idle
System will aggressively enter sleep
Wake On Timer
Enables the system to wake on timerE.g., scheduled task, Media Center PVR
Disable wake on timer to prevent spurious wake events
Most appropriate for mobile PCsSome PCs already do this on DC power with EC/BIOS implementation
Will disable any timer-based wakeMedia center PVR
Windows Update
Doze to Hibernate
… and any other timer
Wake On Timer
Friendly Name Allow Windows to wake on Timer
Description Allow Windows to automatically wake your computer on a timer for scheduled tasks and other programs
GUID bd3b718a-0680-4d9d-8ab2-e1d2b4ac806d
PowerCfg Alias n/a
Balanced Defaults
Enabled (AC) Enabled (DC)
USB Host Controller Power State
USB host controllers armed for wake by default in Windows Vista
When entering sleep, host controllers will be placed in D2 if system supports wake from USB
Will keep power planes on if USB wake enabled
New USB registry option allows the host controller to enter D3
If no wake-armed devices are connected when system sleeps
Helps improve S3 battery life
USB Host Controller Power State
RequirementsSystem supports wake from USBACPI-enumerated USB controllers_PRW indicates lowest wake state >= S3_S3D == 0x2 (S3 -> D2)
Registry Key HKLM\SYSTEM\CurrentControlSet\Servicces\USB
Value (DWORD) ForceHcD3NoWakeArm == 0x1
Default Disabled
Power Optimization Benefits
Power policy changes have tangible impact on energy efficiency
PolicyDefault Value
Modified Value
Domain Idle Accounting Enabled Disabled
HDD Idle Timeout 30 minutes 2 minutes
SATA AHCI DIPM Disabled Enabled
802.11 Power Save Mode
Maximum Performance
Maximum Power Savings
Search and Indexing Balanced Power Saver
ScenarioDefault Runtime Average
Modified Runtime Average
Idle 235 minutes 253 minutes (+7%)
Power Optimization Benefits
DetailsIntel Core 2 Duo-based systems with integrated (GMA 950) graphics1 GB RAM, 60GB SATA HDDWindows Vista RTM, build 6000Latest drivers from manufacturer web site
Platform Design Best Practices
Review preload software for energy efficiency
Compare battery life of clean install to preload Work with ISVs and IHVs on energy efficiency improvements
Also scrutinize IHV software services and value add applicationsIntegrate with Vista power policy
Platform Design Best Practices
USB opportunitiesValidate USB-connected value-add devices support selective suspend
Fingerprint readers, webcams, etc
Avoid integrated USB hubsProcessor idle state utilization impactS3 resume delaysNeed to power the hub device itself
Platform Design Best Practices
Design and integrate low-power devices
Engage with IHVs to integrate device power management with Microsoft Vista power policyAttend the “Designing Power Friendly Devices” session
SYS-T309Speaker: Barnes Cooper, Intel CorporationIn this room, 2:00pm, after lunch
Call To Action
Evaluate energy efficiency and battery life on your platformTailor Windows Vista power policy to hardware platformDesign hardware and preload software for energy efficiency and power savings
Additional ResourcesWeb Resources
Power Policy Configuration and Deployment in Windows Vista http://www.microsoft.com/whdc/system/pnppwr/powermgmt/PMpolicy_Vista.mspx
Windows Vista Energy Conservation http://www.microsoft.com/whdc/system/pnppwr/powermgmt/VistaEnergyConserv.mspx
Related SessionsSYS-T300 – “Designing Power Friendly Devices”
SYS-T494 – “PCs and Energy Efficiency: Implications for IHVs”
SYS-C316- “How To Power Optimize Your Windows Platform
SYS-C315-”Tuning Processor Power Management”
E-mail:
Onnow @ microsoft.com
Battlife @ microsoft.com
© 2007 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.
The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after
the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.