Andrew WHITECHAPELProgram Manager

Managing Resource Constraints in Windows Phone

3-542

Why do you care?What are your choices?Windows Phone Resource Manager.Managing memory.What’s different in Blue?

Agenda

Why do you care?

Make your app available on the widest range of WP devices possible.Ensure users have a great experience with your app on all devices, and at all times.

Why do you care?Make your app available on the widest range of WP devices possible.Ensure users have a great experience with your app on all devices, and at all times.

Memory/hardware constraints can make this an interesting challenge.Windows convergence: a desktop OS on a phone.Disproportionate growth in mid-tier devices.Apps live in an ecosystem on the phone. We did work to scale to devices; now it’s your turn.

Device variability – what are your choices?

Selective targeting. Resilience to variability, and feature

light-up.

Selective targeting

Maximum breadth. Aim for the lowest common denominator. Eliminate non-universal

features/capabilities/memory usage.

Scoped. By OS/platform version (single or multiple app

versions). By device requirements (ID_REQ_*). By device memory.

Resilience and feature light-up

Resilience to platform variability. By device capabilities (ID_CAP_*). Runtime API calls (Is*Supported).

Resilience to dynamic variability. Cell/Network. Battery/PowerSource. Sensor access. Memory.

Demo: optional features

Fixed (per device) and dynamic (per user selection).

Check for optional featuresprivate void GetFixedFeatures(){ Version v = Environment.OSVersion.Version; bool g = Gyroscope.IsSupported; bool a = Accelerometer.IsSupported; bool c = Compass.IsSupported; bool p = Camera.IsCameraTypeSupported(CameraType.Primary); bool f = Camera.IsCameraTypeSupported(CameraType.FrontFacing); int i = App.Current.Host.Content.ScaleFactor;}

private void GetDynamicFeatures(){ bool d = DeviceNetworkInformation.IsCellularDataEnabled; bool r = DeviceNetworkInformation.IsCellularDataRoamingEnabled; bool x = (DeviceStatus.PowerSource == PowerSource.External); ConnectionProfile profile = NetworkInformation.GetInternetConnectionProfile(); ConnectionCost cost = profile.GetConnectionCost();}

private void AddEventHandlers(){ DeviceNetworkInformation.NetworkAvailabilityChanged += OnNetworkAvailabilityChanged; NetworkInformation.NetworkStatusChanged += OnNetworkStatusChanged; DeviceStatus.PowerSourceChanged += OnPowerSourceChanged; PowerManager.PowerSavingModeChanged += OnPowerSavingModeChanged;}

Why? To maintain an optimal user experience across all scenarios.

Memory quotas and caps. CPU quotas and caps. Task priorities. Sensor resources. Monitoring your app’s memory

usage.

Windows Phone resource management

Caps are not quotas.

Memory caps WP8.0 (GDR3)

App/Agent Type 512MB device 1GB device 2GB device

VOIP 51 60 80

Background Audio Playback 20* 25* 25*

Generic Background Agents 11* 20 20

Continuous Background Execution 150 150 150

Foreground App** 150/150/180 150/300/380 150/450/570

*Cannot run concurrently with VOIP.**Min native/Min Silverlight/Max

Foreground App** 150/150/180 150/300/380 150/450/570

More task types.

Higher caps.

No min cap.

Memory caps WP8.1

App/Agent Type 512MB device 1GB device 2GB device

VOIP 51 60 80

Background Audio 20 25 25

Bluetooth 16 16 16

VPN 10 15 15

Calendar Child/FileProvider Target 100 100 100CachedFileUpdater/ShareDataPackage 10 10 10

Background Transfer 5 5 5

WP8 Generic Background Agents 16 20 30

WP8.1 Background Tasks 16 30 40

Continuous Background Execution 150 150 300

Foreground App (WP8.0 context) 180 380 780

Foreground App (modern context) 185 390 825

WP8 Generic Background Agents 16 20 30

WP8.1 Background Tasks 16 30 40

Foreground App (WP8.0 context) 180 380 780

Foreground App (modern context) 185 390 825

Don’t.

Memory cap options

<!-- WP8.1 AppxManifest.xml --><Prerequisites> <m3:MinDeviceMemory>1GB</m3:MinDeviceMemory></Prerequisites>

<!-- WP7 and WP8.0 WMAppManifest.xml --><Requirements> <!--<Requirement Name="ID_REQ_MEMORY_90" />--> <Requirement Name="ID_REQ_MEMORY_300" /></Requirements> <!– Ignored in WP8.1 --><FunctionalCapabilities> <FunctionalCapability Name="ID_FUNCCAP_EXTEND_MEM" /></FunctionalCapabilities>

Memory usage breakdown

Component usage (ballpark) 512MB

Total physical 512

Paging level 200

712

BSP 133

OS, drivers, services 300

OEM/MO service agents 22

VOIP or Background audio 51

Bluetooth 16

VPN 10

532

Foreground App, Back-stack, CBE, GBAs 180

94% of apps peak at <150MB.

96% of apps average at <100MB.

Scenario-based prioritization.

Task Priorities

App/Agent Type Priority

Foreground App 2

VOIP 2

Background Audio 2

Bluetooth 2

VPN 2

Background Transfer 2 or 6*

Calendar Child/FileProvider Target 3

CachedFileUpdater/ShareDataPackage Task 3 or 6*

Continuous Background Execution 4

Geofence-triggered Task 5

WP8.0 Generic Background Agents 6

WP8.1 Background Tasks 6

*Higher priority if part of the Foreground experience.

Monitoring memory usage// WP7.long totalBytes = Microsoft.Phone.Info.DeviceStatus.DeviceTotalMemory;long memUsageLimit = Microsoft.Phone.Info.DeviceStatus.ApplicationMemoryUsageLimit;long currentMemUsage = Microsoft.Phone.Info.DeviceStatus.ApplicationCurrentMemoryUsage;

// WP8.0.ulong committedLimit = Windows.Phone.System.Memory.MemoryManager.ProcessCommittedLimit;ulong committedBytes = Windows.Phone.System.Memory.MemoryManager.ProcessCommittedBytes;

// WP8.1.ulong usageLimit = Windows.System.MemoryManager.AppMemoryUsageLimit;ulong currentUsage = Windows.System.MemoryManager.AppMemoryUsage;MemoryManager.AppMemoryUsageIncreased += OnAppMemoryUsageIncreased;MemoryManager.AppMemoryUsageDecreased += OnAppMemoryUsageDecreased;

private void OnAppMemoryUsageIncreased(object sender, object e){ switch (MemoryManager.AppMemoryUsageLevel) { case AppMemoryUsageLevel.High: break; case AppMemoryUsageLevel.Medium: break; case AppMemoryUsageLevel.Low: break; }}

Demo: monitoring memory usage

AppMemoryUsageLimitChanging

private void Init(){ MemoryManager.AppMemoryUsageLimitChanging += OnAppMemoryUsageLimitChanging;}

private void OnAppMemoryUsageLimitChanging( object sender, AppMemoryUsageLimitChangingEventArgs e){ Debug.WriteLine(String.Format( "AppMemoryUsageLimitChanging: old={0} MB, new={1} MB", (double)e.OldLimit / 1024 / 1024, (double)e.NewLimit / 1024 / 1024));}

Demo: AppMemoryUsageLimitChanging

Example: Background Audio Agent

Sensor resources

Resource Allowed?

Microphone Camera Proximity Gyro Compass Accelerometer Vibrator Push SpeechSynthesis SpeechRecognition Audio InterruptiveUI

Background tasks

CPU quotas. (Partially) converged with Windows RT. Parity in behavior with WP8.0 GBAs. Call BackgroundExecutionManager.RequestAccessAsync

(8.1)

Bluetooth tasks. Short-running: high priority, 30 sec lifetime. Long-running: lower priority, no lifetime cap.

Graphics buffers. One medium tile, one wide tile, one wallpaper.

Battery saver app & battery saver mode.Rude termination (not VOIP/BAP).

Shared Foreground/Background memory

Remove hidden cost imbalances.A VOIP UI app, and its background agents.Any foreground app that invokes a modern background transfer to start while the app is in the foreground.Any foreground app that uses foreground agents.Any foreground app that uses a long-running Bluetooth background task.Any combinations of the above.Subtractions re-added when the background task terminates.

DeviceParticipating tasks Count Cap Max BG Max FG

512MB Background transfer 1 185 5 180

1GB Background transfer 5 390 25 365

Demo: shared fg/bg memory

Use memory APIs to check your usage (debug & release).

Check for optional & user-disabled features. Tailor image resolution to device; use

thumbnails. Launchers instead of full controls. Disable page transitions. Use virtualized lists, load on demand. Test on all your target emulators; focus on the

LCD. Test on real devices. Use the profiler (Windows App Certification

Kit). Use the Windows Phone Developer Power

Tools. Seek out memory spikes.

See Stefan Wick’s talk: 3-545 Quality & Performance.

See Lalithra Fernando’s talk: 4-557 How to Analyze Performance Issues.

Best practices

For maximum success, do work to support the widest range of devices.Your app belongs to a balanced ecosystem.Profile your app, query the device, monitor dynamic features & memory.

Summary

Resources

App memory limits for Windows Phone 8: http://aka.ms/Tfdyf7 Developing apps for lower-memory phones: http://aka.ms/To4as5 The evolution of Windows Phone memory management: http://

aka.ms/Jo85ot Best practice tips for delivering apps with 256 MB: http://aka.ms/Inx8pg Optimizing apps for lower-cost devices: http://aka.ms/Rwt4ll App platform compatibility for Windows Phone: http://aka.ms/Y8fxim Windows Phone 8 Development Internals (book): http://aka.ms/J83ips

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