Writing Energy Efficient Apps

Transcription

1 Session App Frameworks #WWDC17 Writing Energy Efficient Apps 238 Daniel Schucker, Software Power Engineer Prajakta Karandikar, Software Power Engineer 2017 Apple Inc. All rights reserved. Redistribution or public display not permitted without written permission from Apple.

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5 Battery Life Concepts Energy Efficient Coding Energy Debugging Tools and Demo Final Thoughts

6 General Battery Life Concepts

7 What Is Energy? Power Time

8 What Is Energy? Active Active Power Overhead Overhead Idle Time

9 What Is Energy? Active Active Power Overhead Overhead Energy Idle Time

10 What Is Energy? Active Your work Overhead Active Power Overhead Overhead Dynamic cost Fixed cost Idle Time

11 Balancing Power and Battery Life

12 Balancing Power and Battery Life

13 What Consumes Energy?

14 What Consumes Energy? Processing Networking Location Graphics

15 How to Reduce Energy Consumption Identify Optimize Coalesce Reduce

16 Energy Efficient Coding

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18 Social Networking App Main feed Post a photo Analytics

19 Social Networking App Main Feed Current implementation Reloads on a timer

20 Social Networking App Energy Impact Feed Refresh Power Time

21 Social Networking App Energy Impact Feed Refresh Power Time

22 Social Networking App Energy Impact Feed Refresh Radio cost Power Dynamic cost Overhead cost Time

23 Social Networking App Main Feed Reload only when needed User interaction Notification Use NSURLSession Default Session New: WaitsForConnectivity Cache

24 Social Networking App Energy Impact Feed Refresh Radio cost Power User Interaction Notification Dynamic cost Overhead cost Time

25 // Setup NSURLSession Default Session let config = URLSessionConfiguration.default() // Use WaitsForConnectivity config.waitsforconnectivity = true // NSURLSession Cache let cachesdirectoryurl = FileManager.default().urlsForDirectory(.cachesDirectory, indomains:.userdomainmask).first! let cacheurl = try! cachesdirectoryurl.appendingpathcomponent("mycache") var diskpath = cacheurl.path let cache = URLCache(memoryCapacity:16384, diskcapacity: , diskpath: diskpath) config.urlcache = cache config.requestcachepolicy =.useprotocolcachepolicy

26 // Setup NSURLSession Default Session let config = URLSessionConfiguration.default() // Use WaitsForConnectivity config.waitsforconnectivity = true // NSURLSession Cache let cachesdirectoryurl = FileManager.default().urlsForDirectory(.cachesDirectory, indomains:.userdomainmask).first! let cacheurl = try! cachesdirectoryurl.appendingpathcomponent("mycache") var diskpath = cacheurl.path let cache = URLCache(memoryCapacity:16384, diskcapacity: , diskpath: diskpath) config.urlcache = cache config.requestcachepolicy =.useprotocolcachepolicy

27 // Setup NSURLSession Default Session let config = URLSessionConfiguration.default() // Use WaitsForConnectivity config.waitsforconnectivity = true // NSURLSession Cache let cachesdirectoryurl = FileManager.default().urlsForDirectory(.cachesDirectory, indomains:.userdomainmask).first! let cacheurl = try! cachesdirectoryurl.appendingpathcomponent("mycache") var diskpath = cacheurl.path let cache = URLCache(memoryCapacity:16384, diskcapacity: , diskpath: diskpath) config.urlcache = cache config.requestcachepolicy =.useprotocolcachepolicy

28 // Setup NSURLSession Default Session let config = URLSessionConfiguration.default() // Use WaitsForConnectivity config.waitsforconnectivity = true // NSURLSession Cache let cachesdirectoryurl = FileManager.default().urlsForDirectory(.cachesDirectory, indomains:.userdomainmask).first! let cacheurl = try! cachesdirectoryurl.appendingpathcomponent("mycache") var diskpath = cacheurl.path let cache = URLCache(memoryCapacity:16384, diskcapacity: , diskpath: diskpath) config.urlcache = cache config.requestcachepolicy =.useprotocolcachepolicy

29 Social Networking App Posting a Photo Current implementation Send immediately Retry on failure

30 Social Networking App Energy Impact Send photo cost Radio cost Power Send Photo Timeout Dynamic cost Overhead cost Time

31 Social Networking App Energy Impact Send photo cost Radio cost Power Send Photo Timeout Retry Timeout Dynamic cost Overhead cost Time

32 Social Networking App Posting a Photo Use NSURLSession Default Session Minimize retries Set timeouts Batch Transactions When retry limit hit Use Background Session

33 Social Networking App Energy Impact Send photo cost Radio cost Power Send Photo Timeout Retry Timeout Create Background Session Dynamic cost Overhead cost Time

34 Social Networking App Sending analytics data Use NSURLSession Background Session Automatic retries Throughput monitoring Analytics Properties New - Start time - Workload size Discretionary

35 Social Networking App Sending analytics data Use NSURLSession Background Session Automatic retries Throughput monitoring Analytics Properties New - Start time - Workload size Discretionary

36 Social Networking Application Energy Impact Send analytics cost Other networking cost Radio cost Power Dynamic cost Overhead cost Time

37 Social Networking Application Energy Impact Send analytics cost Other networking cost Radio cost Power Dynamic cost Overhead cost Time

38 // Setup NSURLSession Background Session let config = URLSessionConfiguration.background(withIdentifier: "com.socialapp.background") let session = URLSession(configuration: config, delegate:, delegatequeue: ) // Set discretionary property config.discretionary = true // Create Request and Task var request = URLRequest(url: URL(string: " request.addvalue(" ", forhttpheaderfield: ) let task = session.downloadtask(with: request) // Set time window task.earliestbegindate = Date(timeIntervalSinceNow: 2 * 60 * 60) // Set workload size task.countofbytesclientexpectstosend = 80 task.countofbytesclientexpectstoreceive = 2048 task.resume()

39 // Setup NSURLSession Background Session let config = URLSessionConfiguration.background(withIdentifier: "com.socialapp.background") let session = URLSession(configuration: config, delegate:, delegatequeue: ) // Set discretionary property config.discretionary = true // Create Request and Task var request = URLRequest(url: URL(string: " request.addvalue(" ", forhttpheaderfield: ) let task = session.downloadtask(with: request) // Set time window task.earliestbegindate = Date(timeIntervalSinceNow: 2 * 60 * 60) // Set workload size task.countofbytesclientexpectstosend = 80 task.countofbytesclientexpectstoreceive = 2048 task.resume()

40 // Setup NSURLSession Background Session let config = URLSessionConfiguration.background(withIdentifier: "com.socialapp.background") let session = URLSession(configuration: config, delegate:, delegatequeue: ) // Set discretionary property config.discretionary = true // Create Request and Task var request = URLRequest(url: URL(string: " request.addvalue(" ", forhttpheaderfield: ) let task = session.downloadtask(with: request) // Set time window task.earliestbegindate = Date(timeIntervalSinceNow: 2 * 60 * 60) // Set workload size task.countofbytesclientexpectstosend = 80 task.countofbytesclientexpectstoreceive = 2048 task.resume()

41 Social Networking Application WatchOS Use background session for screen off work Complication updates Background app refresh Runtime when task completes

42 Networking Best Practices Identify Ensure transactions not repeated Optimize Use background session Coalesce Batch transactions Reduce Minimize retries

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44 Location Best Practices Location APIs Continuous location Quick location update Region monitoring Visit monitoring Significant location change

45 Location Best Practices Continuous Location Navigate to a destination Continuous location updates Prevents device sleep Stop location updates Allows device to sleep

46 // Create location manager locationmanager = CLLocationManager() locationmanager.delegate = self locationmanager.requestwheninuseauthorization() // Set desired accuracy, auto-pause, and activity type appropriately locationmanager.desiredaccuracy = kcllocationaccuracythreekilometers locationmanager.pauseslocationupdatesautomatically = true locationmanager.activitytype = CLActivityTypeNavigation // Set allows background if its needed locationmanager.allowsbackgroundlocationupdates = true // Start location updates locationmanager.startupdatinglocation()

47 // Create location manager locationmanager = CLLocationManager() locationmanager.delegate = self locationmanager.requestwheninuseauthorization() // Set desired accuracy, auto-pause, and activity type appropriately locationmanager.desiredaccuracy = kcllocationaccuracythreekilometers locationmanager.pauseslocationupdatesautomatically = true locationmanager.activitytype = CLActivityTypeNavigation // Set allows background if its needed locationmanager.allowsbackgroundlocationupdates = true // Start location updates locationmanager.startupdatinglocation()

48 // Create location manager locationmanager = CLLocationManager() locationmanager.delegate = self locationmanager.requestwheninuseauthorization() // Set desired accuracy, auto-pause, and activity type appropriately locationmanager.desiredaccuracy = kcllocationaccuracythreekilometers locationmanager.pauseslocationupdatesautomatically = true locationmanager.activitytype = CLActivityTypeNavigation // Set allows background if its needed locationmanager.allowsbackgroundlocationupdates = true // Start location updates locationmanager.startupdatinglocation()

49 // Create location manager locationmanager = CLLocationManager() locationmanager.delegate = self locationmanager.requestwheninuseauthorization() // Set desired accuracy, auto-pause, and activity type appropriately locationmanager.desiredaccuracy = kcllocationaccuracythreekilometers locationmanager.pauseslocationupdatesautomatically = true locationmanager.activitytype = CLActivityTypeNavigation // Set allows background if its needed locationmanager.allowsbackgroundlocationupdates = true // Start location updates locationmanager.startupdatinglocation()

50 // Create location manager locationmanager = CLLocationManager() locationmanager.delegate = self locationmanager.requestwheninuseauthorization() // Set desired accuracy, auto-pause, and activity type appropriately locationmanager.desiredaccuracy = kcllocationaccuracythreekilometers locationmanager.pauseslocationupdatesautomatically = true locationmanager.activitytype = CLActivityTypeNavigation // Set allows background if its needed locationmanager.allowsbackgroundlocationupdates = true // Start location updates locationmanager.startupdatinglocation()

51 // Start location updates locationmanager.startupdatinglocation() // Get location updates // Disable background updates when no longer needed locationmanager.allowsbackgroundlocationupdates = false // Stop location when no longer needed locationmanager.stopupdatinglocation()

52 // Start location updates locationmanager.startupdatinglocation() // Get location updates // Disable background updates when no longer needed locationmanager.allowsbackgroundlocationupdates = false // Stop location when no longer needed locationmanager.stopupdatinglocation()

53 // Start location updates locationmanager.startupdatinglocation() // Get location updates // Disable background updates when no longer needed locationmanager.allowsbackgroundlocationupdates = false // Stop location when no longer needed locationmanager.stopupdatinglocation()

54 Location Best Practices Request location Get news based on current location Use quick location update locationmanager.requestlocation()

55 Location Best Practices Request location Get news based on current location Use quick location update locationmanager.requestlocation()

56 Location Best Practices Region monitoring Updating content when arriving at home Use region monitoring // Create the geographic region to be monitored. let georegion = CLCircularRegion(center: overlay.coordinate, radius: radius, identifier: identifier) locationmanager.startmonitoring(for: georegion)

57 Location Best Practices Region monitoring Updating content when arriving at home Use region monitoring // Create the geographic region to be monitored. let georegion = CLCircularRegion(center: overlay.coordinate, radius: radius, identifier: identifier) locationmanager.startmonitoring(for: georegion)

58 Location Best Practices Visit monitoring Updating content when arriving at frequently visited locations Use visit monitoring // Start monitoring locationmanager.startmonitoringvisits() // Stop monitoring when no longer needed locationmanager.stopmonitoringvisits()

59 Location Best Practices Visit monitoring Updating content when arriving at frequently visited locations Use visit monitoring // Start monitoring locationmanager.startmonitoringvisits() // Stop monitoring when no longer needed locationmanager.stopmonitoringvisits()

60 Location Best Practices Visit monitoring Updating content when arriving at frequently visited locations Use visit monitoring // Start monitoring locationmanager.startmonitoringvisits() // Stop monitoring when no longer needed locationmanager.stopmonitoringvisits()

61 Location Best Practices Significant location change Updating content based user location Use significant location change // Start monitoring locationmanager.startmonitoringsignificantlocationchanges() // Stop monitoring when no longer needed locationmanager.stopmonitoringsignificantlocationchanges()

62 Location Best Practices Significant location change Updating content based user location Use significant location change // Start monitoring locationmanager.startmonitoringsignificantlocationchanges() // Stop monitoring when no longer needed locationmanager.stopmonitoringsignificantlocationchanges()

63 Location Best Practices Significant location change Updating content based user location Use significant location change // Start monitoring locationmanager.startmonitoringsignificantlocationchanges() // Stop monitoring when no longer needed locationmanager.stopmonitoringsignificantlocationchanges()

64 Location Best Practices Identify: Accuracy level needed Optimize: Use alternatives to continuous location Reduce: Stop location when not used Coalesce: Defer location updates

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66 Graphics Minimize screen updates Ensure screen updates provide needed changes Review blur usage Avoid placing blurs over updating elements

67 Graphics MacOS Minimize use of Discrete GPU Use Discrete GPU only when: Animation performance suffers Functionality isn't supported

68 Graphics MacOS Metal MTLCreateSystemDefaultDevice() Always uses Discrete GPU Use Integrated GPU when possible MTLCopyAllDevices - Select device with islowpower attribute set

69 Graphics MacOS OpenGL Make your app mux-aware by either: Adding NSSupportsAutomaticGraphicsSwitching to your info.plist Creating an OpenGL context with the automatic graphics switching attribute let attributes3 : [CGLPixelFormatAttribute] = [ kcglpfasupportsautomaticgraphicsswitching, kcglpfaallowofflinerenderers, CGLPixelFormatAttribute(0) ] CGLChoosePixelFormat(attributes3, &pix, &npix) CGLCreateContext(pPixelFmt, nil, &pcontext)

70 Graphics Best Practices Identify: Blur usage Optimize: Only use discrete GPU when needed (macos) Reduce: Minimize screen updates

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72 Processing Best Practices Identify tasks Do work quickly and efficiently Avoid timers Set leeway

73 Background Processing Foregrounded Foreground work Background work Overhead Backgrounded Suspended Power Dynamic cost Fixed cost Idle Time

74 Background Processing Finish work quickly Use background app refresh Call completion handler

75 Background Processing ios PushKit API Now has completion handler Call after handling push func pushregistry(_ registry: PKPushRegistry, didreceiveincomingpushwith payload: PKPushPayload, fortype type: PKPushType, withcompletionhandler () -> Void) { // Process the incoming push payload here... } // Then signal that processing has completed completion()

76 Background Processing ios PushKit API Now has completion handler Call after handling push func pushregistry(_ registry: PKPushRegistry, didreceiveincomingpushwith payload: PKPushPayload, fortype type: PKPushType, withcompletionhandler () -> Void) { // Process the incoming push payload here... } // Then signal that processing has completed completion()

77 Background Processing Current Background work Overhead Incoming Push Power Suspended Dynamic cost Fixed cost Idle Time

78 Background Processing With Completion Handler Background work Overhead Incoming Push Completion Handler Power Dynamic cost Fixed cost Idle Time

79 Background Processing WatchOS New: Navigation background mode CPU limits like Workout Minimize networking Ensure work is relevant to the user Use background app refresh and complication updates to refresh data

80 Background Processing Identify: Work done in the background Optimize: Use Background App Refresh Reduce: Limit transactions Coalesce: Use NSURLSession background session

81 Battery Life Concepts Energy Efficient Coding Energy Debugging Tools and Demo Final Thoughts

82 Overview Energy debugging tools Measuring energy impact of your apps Demo

83 Settings: Battery

84 Settings: Battery Can be deleted by users

85 Energy Debugging Workflow Energy Gauges

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118 Scenarios for Energy Debugging General/common Launch and Idle Background Application specific For example, Navigation App - Search for an address - Get directions - Navigate

119 Demo

120 Battery Life Concepts Energy Efficient Coding Energy Debugging Tools and Demo Final Thoughts

121 Final Thoughts Use NSURLSession Background Session Minimize use of continuous location Avoid timers Coalesce work Use energy gauges

122 Related Sessions Advances in Networking, Part 1 Executive Ballroom Wednesday 3:00PM Advances in Networking, Part 2 Executive Ballroom Wednesday 4:00PM NSURLSession: New Features and Best Practices WWDC 2016 Networking for the Modern Internet WWDC 2016

123 Labs Power and Performance Lab Technology Lab I Fri 11:00AM 1:00PM

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