Windows 7 Power Management OverviewPat Stemen

Senior Program ManagerMicrosoft Corporation

The Power of WinHEC 2008!

COR-T540 Windows 7 Power Management Overview Now

MBL-T541 Improving Platform Energy Efficiency (part 1) Today, 2:00–3:00Room 404

MBL-T541 Improving Platform Energy Efficiency (part 2) Today, 3:15–4:15Room 404

COR-C622 Discussion: Windows 7 Power Management Today, 4:30–5:30

Room 402A

COR-T542

NDIS 6.20: Core Network Power Management Fundamentals

Today, 4:30–5:30Room 404

ENT-T551 Windows Server Power Management OverviewThursday, 2:00–3:00Hall K

ENT-T552 Windows Server Power Management Implementation Details

Thursday, 3:15–4:15Hall K

COR-C633 Microsoft Tools for Energy Efficiency Diagnostics

Thursday, 2:00–3:00Room 402A

Agenda

Windows Energy Efficiency VisionIdle Power and Background ActivityDevice Power ManagementTimers and AlarmsPower Policy EnhancementsIdle DetectionPower Efficiency Diagnostics

Windows Energy Efficiency VisionThe Windows OS enables the most energy-efficient computing platform, regardless of underlying hardware, attached devices or software workload.

Idle Efficiency

Workload Scaling

Always Available

SelfDiagnosing

Standards Based

Management

Extensible but Resilient

Deep Focus on Idle

6

0 20 40 60 80 100 -

5.00

10.00

15.00

20.00

25.00

30.00

35.00

40.00

System Power vs. CPU Uti-lization(Idle)

CPU Utilization (%)

Tota

l S

yst

em

Po

we

r (W

att

s)

+10% CPU increases power by ~1.25W

1.25W increase results in 8.3% reduction in battery

life Clean Install

IT Image0%1%2%3%4%5%6%7%8%

CPU Utilization on Idle System

CP

U U

tili

za

tio

n (

%)

Background Activity Improvements

Idle dominates almost all use scenarios for client systems

Reducing idle power key to extending battery life

Periodic background activity increases system power consumption

Very frequent events impact processor and chipset powerLong-running infrequent events prevent the system from idling to sleep

Frequent Idle Activity

Specific Windows 7 improvementsEliminate TCP DPC timer on every system timer interruptReduce frequency of USB driver maintenance timersIntelligent Timer Tick Distribution (ITTD)Timer Coalescing

Eliminate idle activity in drivers and applications

Target average idle period greater than 100ms

Timer Coalescing

Platform energy efficiency can be improved by extending idle periods

New timer coalescing API enables callers to specify a tolerance for due time

Enables the kernel to expire multiple timers at the same time

Extensions should integrate with Windows 7 API/DDI

Timer tick15.6 ms

Periodic Timer Events

Windows 7

Vista

Background Process Management

Background activity on the macro scale (minutes, hours) also important for power

E.g., disk defragmentation, AV scans

Prevents low-power idle and sleep modes

Unified Background Process Manager (UBPM)New Windows 7 infrastructure

Drives scheduling of services and scheduled tasks

Transparent to users, IT pros, and existing APIs

Enables trigger-starting services

Delivers usage data and metrics to Microsoft via CEIP

Trigger-Start Services

Many services configured to Autostart and wait for rare events

UBPM enables Trigger-Start services based on environmental changes

Device arrival/removal, IP address change, domain join, etc.

Examples

Bluetooth service is started only if a Bluetooth radio is currently attached

BitLocker encryption service started only when new volumes detected

Call to ActionLeverage trigger-start capability for value-add services

Validate performance impact with XPerf tools

Some Trigger-Start Services In Windows 7

Service Name Description Trigger Type

AELookupSvc Processes application compatibility cache requests for applications as they are launched

Custom ETW

BDESVC Provides BitLocker client services for user interface and auto-unlocking of data volumes

Custom ETW

BTHSERV The Bluetooth service supports discovery and association of remote Bluetooth devices.

Device

SensorsMTPMonitor Monitors MTP (Media Transfer Protocol) sensors (such as a cell phone with a GPS receiver) to communicate sensor data to programs

Device

TabletInputService Enables Tablet PC pen and ink functionality

Device

WinDefend Protection against spyware and potentially unwanted software

Group Policy

Device Power Management

Adaptive display brightnessDim the mobile PC display after a period of user inactivity

Intelligent policy—timeout automatically adjusts with user input

Does not interfere with presentations, full-screen media playback

Processor power managementUpdates to core performance state algorithm

Core parking

Device Power Management

AudioSupport for the latest Intel HD Audio low-power specificationsUSB audio class selective suspend

BluetoothRadio enters selective suspend when connections are in sniff mode

Wired LAN runtime idle detectionNIC automatically enters D3 when media is disconnected

Power Policy Enhancements

Iterative evolution of Vista power policyContinue 3 plans: Performance, Balanced, Power Saver

Same toolset

Refined UI elements

New power settings for Windows 7 features

Minor changes to idle timeout defaults

OEMs must continue to tailor policy for specific platforms

E.g., meet regulatory compliance standards

New Windows 7 Power Policies

Name GUID Description

Default (Balanced)

AC DC

Unattended sleep timeout

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Determines the amount of inactivity time before the system automatically sleeps if the computer resumed without a user present

2 minutes2

minutes

System cooling policy

94d3a615-a899-4ac5-ae2b-e4d8f634367f

Determines if Active or Passive cooling should be favored for thermal zones

Active Active

Reserve battery level

f3c5027d-cd16-4930-aa6b-90db844a8f00

Configures the percentage of battery capacity remaining before displaying the reserve battery warning

n/a 7%

AHCI link power mode

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Configures AHCI link power modes (HIPM, DIPM) and link power states (Partial, Slumber, Active)

HIPM, Partial

HIPM, Slumber

Allow System Required

Policy

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Enable applications to prevent the system from idling to sleep

Enabled Enabled

Dim Display After

17aaa29b-8b43-4b94-aafe-35f64daaf1ee

Determines the amount of inactivity time before the system automatically reduces the brightness of the display on a mobile PC

5 minutes2

minutes

Power WMI Provider

Enables power policy configuration through standard WMI interface

Change power setting values

Activate a given plan

Conforms to DMTF data model

To get started…Change a power setting: Win32_PowerSetting

Activate a plan: Win32_Plan.Activate() method

Attend ENT-T552 Windows Server Power Management Implementation Details for additional details

Wake Timers

Opportunity to improve mobile PC experience by reducing spurious wake events

E.g., system wakes up in bag due to application request, remains on, drains battery

Windows 7 mobile PCs will not program wake timer alarm by default

Excludes doze to hibernate

Wake timers continue to be enabled by default on desktop systems

Power policy control to configure wake timers

Low Battery Experience

7%

16%

5%

Automatic Hibernate

All thresholds are configurable in power policy

Media Playback Improvements

Refined optical drive spin-down mechanismConfigurable power policies to force interlaced content to render at 30 fpsCPU utilization improvements for copy-protection and DRM complianceArchitectural changes in DWM to optimize CPU and memory utilizationAttend MBL-T541 Improving Platform Energy Efficiency for detailed power savings information

Idle Detection

Windows 7 is aggressive about placing

the system in sleep when idleUser input and application availability requests only

Availability requests allow applications

to request temporary overrides on power management

Media center recording service prevents idle to sleep when recording TVWindows Media Player prevents display from turning off while watching DVD

Idle Detection

Windows 7 improves failed idle detection diagnostics

Use PowerCfg utility to inspect for requestsPowerCfg /REQUESTS

Network file sharingOpen files in a client-side cache (offline files) will not prevent the client from sleeping

Policy override capabilityOption to override individual availability requests

Option to override all availability requestsIdle detection will be based solely on user input

Idle Detection Diagnostics

demo

Power Efficiency Diagnostics

PowerCfg command-line utility expanded to detect common energy efficiency problems

USB device selective suspend

Processor Power Management (PPM)

Inefficient power policy settings

Platform timer resolution

Platform firmware problems

Battery capacity

…and others

Helps detect major problems at time of system integration

Power Efficiency Diagnostics

Designed to evaluate problems when the system is idle

Close open applications and documents

“PowerCfg /ENERGY” at the command line to start tracing

Inbox with Windows 7 onlyLeverages new inbox ETW instrumentation

Advanced users can run utility and view HTML output

Automatically executed when the system is idleReports data to Microsoft via Customer Experience Improvement Program (CEIP)

Attend COR-C633 Microsoft Tools for Energy Efficiency Diagnostics for demo and details

Power Efficiency DiagnosticsDetected problems

Problem Area Data Collected Warning

ThresholdError

Threshold

USB Device Selective Suspend

Individual device suspend transitions

% of time device was in suspend state

< 80% suspend time

< 50% suspend time

Power Policy

Settings

Idle timeouts (dim, display, sleep)

PPM configuration

Power plan personality

802.11 Wireless Power Save

Idle timeouts < EnergyStar 4.0 Recommendations

Idle timeouts disabled

Processor Utilization

Overall utilization

Per-process utilization (any process over .1%)

Top 3 module utilization in each process

Total utilization >2%

Total utilization > 4%

Power Efficiency DiagnosticsDetected problems

Problem Area Data Collected Warning

ThresholdError

Threshold

Timer Resolution Requests

Current system timer interrupt period (e.g., 15.6ms)

Applications with outstanding timer requests, request amount

None Timer interrupt period < 15.6ms

Power Requests

Applications with outstanding power requests (Display, Sleep, Away Mode)

NoneEach outstanding power request

Platform Capabilitie

s

Sleep state availability

Display dimming capability

Firmware validation problems

PCI Express ASPM status

NoneIf any capability is disabled or missing

Battery Capacity

Battery static data (make, model, serial number, manufacture date)

Last full charge capacity/design capacity

(Last Full Charge Capacity/Designed Capacity) < 50%

(Last Full Charge Capacity/Designed Capacity) < 40%

Call to Action

Attend power and energy efficiency sessions at WinHECFocus on idle—reduce idle activity and power consumptionConvert value-add and custom services to trigger-start modelReview new power policy options, tailor for specific platformsValidate new platform power management using Power Efficiency Diagnostics

Additional ResourcesWeb Resources

Windows Hardware Developer Central – ACPI / Power Managementhttp://www.microsoft.com/whdc/system/pnppwr/powermgmt/default.mspx

Battery Life and Energy Efficiencyhttp://www.microsoft.com/whdc/system/pnppwr/mobilepwr.mspx

Designing Efficient Background Processes for Windows (Trigger-Start Services) http://go.microsoft.com/fwlink/?LinkId=128622

Power Policy Configuration and Deployment in Windows Vista http://www.microsoft.com/whdc/system/pnppwr/powermgmt/PMpolicy_Vista.mspx

Related SessionsMBL-T541 – Improving Platform Energy EfficiencyCOR-C633 – Microsoft Tools for Energy Efficiency DiagnosticsCOR-C622 – Discussion: Windows 7 Power ManagementENT-T551 – Windows Server Power Management OverviewENT–T552 – Windows Server Power Management Implementation Details

Emailenergy@microsoft.com

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