Writing Energy Efficient Code

Transcription

1 Core OS #WWDC14 Writing Energy Efficient Code Part 1 Session 710 Anthony Chivetta OS X Performance & Power 2014 Apple Inc. All rights reserved. Redistribution or public display not permitted without written permission from Apple.

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5 What You ll Learn

6 What You ll Learn Power and energy concepts

7 What You ll Learn Power and energy concepts Improving your energy use

8 What You ll Learn Power and energy concepts Improving your energy use Do it never

9 What You ll Learn Power and energy concepts Improving your energy use Do it never Do it at a better time

10 What You ll Learn Power and energy concepts Improving your energy use Do it never Do it at a better time Do it more efficiently

11 What You ll Learn Power and energy concepts Improving your energy use Do it never Do it at a better time Do it more efficiently Do it less

12 What You ll Learn Power and energy concepts Improving your energy use Do it never Do it at a better time Do it more efficiently Do it less Part 2

13 What You ll Learn Power and energy concepts Improving your energy use Do it never Do it at a better time Do it more efficiently Do it less Part 2 Networking

14 What You ll Learn Power and energy concepts Improving your energy use Do it never Do it at a better time Do it more efficiently Do it less Part 2 Networking Location

15 What You ll Learn Power and energy concepts Improving your energy use Do it never Do it at a better time Do it more efficiently Do it less Part 2 Networking Location Sleep/Wake

16 What Uses Energy? CPU (not an exhaustive list)

17 What Uses Energy? CPU Storage (not an exhaustive list)

18 What Uses Energy? CPU Storage Networking (not an exhaustive list)

19 What Uses Energy? CPU Storage Networking Graphics (not an exhaustive list)

20 Fixed Costs Power Time

21 Fixed Costs Power Time

22 Fixed Costs Power Idle Power Time

23 Fixed Costs System Active Power Idle Power Time

24 Fixed Costs System Active Intermediate States Power Idle Power Time

25 Fixed Costs System Active Intermediate States Power Dynamic Cost Fixed Cost Idle Power Time

26 Fixed Costs Power Time

27 Fixed Costs Small Sporadic Work Power Time

28 Fixed Costs Small Sporadic Work Power Time

29 Fixed Costs Small Sporadic Work Power Time

30 Fixed Costs Power Time

31 Energy and Power Power Time

32 Energy and Power Power Power Time

33 Energy and Power Power Power Energy Time

34 Trading Power for Energy Power Single-Threaded Time

35 Trading Power for Energy Power Single-Threaded Time

36 Trading Power for Energy Power Single-Threaded Multi-Threaded Time

37 Power Fundamentals Work has a fixed cost For small workloads, this can dominate For intensive workloads, dynamic cost will dominate Better performance = less energy

38 Do It Never

39 Avoid Unneeded Work Your App Your Ad

40 Avoid Unneeded Work Your App Your Ad

41 Avoid Unneeded Work Your App Your Ad

42 Avoid Unneeded Work Your App Another App Your Ad

43 Active App Transitions ios - (void)applicationdidresignactive: (UIApplication *)application { // Pause animations and UI updates }! - (void)applicationdidbecomeactive: (UIApplication *)application { // Resume animations and UI updates }! Or, listen for the UIApplicationWillResignActiveNotification notification.

44 Active App Transitions OS X - (void)applicationdidresignactive:(nsnotification *)anotification { // Pause animations and UI updates }! - (void)applicationdidbecomeactive:(nsapplication *)anotification { // Resume animations and UI updates }! Or, listen for the NSApplicationDidResignActiveNotification notification.

45 Occlusion Notifications

46 Occlusion Notifications Occlusion notifications indicate visibility of windows or applications

47 Occlusion Notifications Occlusion notifications indicate visibility of windows or applications For applications, implement delegate method - (void)applicationdidchangeocclusionstate:(nsnotification *)notification Or check if ([NSApp occlusionstate] & NSApplicationOcclusionStateVisible)

48 Occlusion Notifications Occlusion notifications indicate visibility of windows or applications For applications, implement delegate method - (void)applicationdidchangeocclusionstate:(nsnotification *)notification Or check if ([NSApp occlusionstate] & NSApplicationOcclusionStateVisible) For windows, implement delegate method - (void)windowdidchangeocclusionstate:(nsnotification *)notification Or check if ([window occlusionstate] & NSWindowOcclusionStateVisible)

49 App Nap

50 App Nap App Nap reduces an inactive app s energy use

51 App Nap App Nap reduces an inactive app s energy use App Nap relies on heuristics

52 App Nap App Nap reduces an inactive app s energy use App Nap relies on heuristics You are the authoritative source for what work is important

53 App Nap App Nap reduces an inactive app s energy use App Nap relies on heuristics You are the authoritative source for what work is important In a well-behaved app, App Nap should never be in effect during work

54 App Nap App Nap reduces an inactive app s energy use App Nap relies on heuristics You are the authoritative source for what work is important In a well-behaved app, App Nap should never be in effect during work -NSProcessInfo (void)performactivitywithoptions:(nsactivityoptions)options reason:(nsstring *)reason usingblock:(void (^)(void))block

55 Avoiding Unnecessary Work Monitor app state to know when work isn t visible Avoid updating UI until the user can see the results Nap yourself when not in use, so App Nap doesn t have to

56 Do It at a Better Time

57 Do It at a Better Time On Power Battery Remaining 6AM Noon 6PM

58 Do It at a Better Time On Power Battery Remaining 6AM Noon 6PM

59 Do It at a Better Time User runs your app On Power Battery Remaining 6AM Noon 6PM

60 Do It at a Better Time User runs your app On Power Battery Remaining 6AM Noon 6PM

61 Do It at a Better Time User runs your app On Power Battery Remaining Window 6AM Noon 6PM

62 Do It at a Better Time User runs your app On Power Battery Remaining Window 6AM Noon 6PM

63 Do It at a Better Time User runs your app On Power Battery Remaining Window 6AM Noon 6PM

64 NSBackgroundActivityScheduler

65 NSBackgroundActivityScheduler New API in OS X Yosemite

66 NSBackgroundActivityScheduler New API in OS X Yosemite Allows scheduling arbitrary tasks for a good time in the future

67 NSBackgroundActivityScheduler New API in OS X Yosemite Allows scheduling arbitrary tasks for a good time in the future Supports repeating or non-repeating activities

68 NSBackgroundActivityScheduler New API in OS X Yosemite Allows scheduling arbitrary tasks for a good time in the future Supports repeating or non-repeating activities Can be used to schedule Periodic content fetch Update install Garbage collection and data maintenance tasks Automatic saves or backups

69 Creating a Scheduler activity = [[NSBackgroundActivityScheduler alloc] initwithidentifier:@ com.apple.sample-app.myactivity ];! Each activity must have an identifier Identifier should be in reverse-dns style Name should be unique, but the same across app runs com.example.myapp.updatecheck

70 Specifying Scheduling Properties // Activity will fire in the next 10 minutes activity.tolerance = 10 * 60;

71 Specifying Scheduling Properties // Activity will fire in the next 10 minutes activity.tolerance = 10 * 60; // Activity will fire between 15 and 45 minutes from now activity.interval = 30 * 60; activity.tolerance = 15 * 60;

72 Specifying Scheduling Properties // Activity will fire in the next 10 minutes activity.tolerance = 10 * 60; // Activity will fire between 15 and 45 minutes from now activity.interval = 30 * 60; activity.tolerance = 15 * 60; // Activity will fire once each hour activity.repeats = YES activity.interval = 60 * 60;

73 Scheduling Your Work

74 Scheduling Your Work [activity schedulewithblock:^(nsbackgroundactivitycompletionhandler completion){!!!!!! // do the work }]; completion(nsbackgroundactivityresultfinished);

75 Scheduling Your Work Deferring in-progress work [activity schedulewithblock:^(nsbackgroundactivitycompletionhandler completion){ for ( /* each item of work */) { if (activity.shoulddefer){ completion(nsbackgroundactivityresultdeferred); return; } // do item of work } completion(nsbackgroundactivityresultfinished); }];

76 Scheduling Your Work Deferring in-progress work [activity schedulewithblock:^(nsbackgroundactivitycompletionhandler completion){ for ( /* each item of work */) { if (activity.shoulddefer){ completion(nsbackgroundactivityresultdeferred); return; } // do item of work } completion(nsbackgroundactivityresultfinished); }];

77 NSBackgroundActivityScheduler You specify scheduling requirements for work

78 NSBackgroundActivityScheduler You specify scheduling requirements for work System select the best time to perform that work

79 NSBackgroundActivityScheduler You specify scheduling requirements for work System select the best time to perform that work Support for repeating tasks without drift

80 NSBackgroundActivityScheduler You specify scheduling requirements for work System select the best time to perform that work Support for repeating tasks without drift Available in OS X Yosemite or with the xpc_activity C API in 10.9

81 NSURLSession Background Session Your App

82 NSURLSession Background Session Your App NSURLRequest NSURLRequest NSURLRequest

83 NSURLSession Background Session Your App NSURLRequest NSURLSession with Background Session Configuration NSURLRequest NSURLRequest NSURLSessionDelegate

84 NSURLSession Background Session Your App Out of Process Session NSURLRequest NSURLRequest NSURLSession with Background Session Configuration Task Task NSURLRequest NSURLSessionDelegate Task

85 NSURLSession Background Session Your App Out of Process Session NSURLRequest NSURLRequest NSURLSession with Background Session Configuration Task Task NSURLRequest NSURLSessionDelegate Task

86 NSURLSession Background Session Out of Process Session Task Task Task

87 NSURLSession Background Session Out of Process Session Task Task Task

88 NSURLSession Background Session Your App Out of Process Session Task Task Task

89 NSURLSession Background Session Your App Out of Process Session NSURLSession with Background Session Configuration Task Task NSURLSessionDelegate Task + backgroundsessionconfigurationwithidentifier: com.example.mysessionidentifier

90 Discretionary Tasks

91 Discretionary Tasks configuration.discretionary = YES;

92 Discretionary Tasks configuration.discretionary = YES; Discretionary sessions available in ios 7.0 and OS X Yosemite

93 Discretionary Tasks configuration.discretionary = YES; Discretionary sessions available in ios 7.0 and OS X Yosemite Automatically picks the best time to do work

94 Discretionary Tasks configuration.discretionary = YES; Discretionary sessions available in ios 7.0 and OS X Yosemite Automatically picks the best time to do work Provides bandwidth monitoring and automatic retry

95 Discretionary Tasks configuration.discretionary = YES; Discretionary sessions available in ios 7.0 and OS X Yosemite Automatically picks the best time to do work Provides bandwidth monitoring and automatic retry Scheduling window can be adjusted with configuration.timeoutintervalforresource = 24*60*60; // 1 day If this time elapses, an error will be thrown Should be >12 hours

96 Related Session What s New in Foundation Networking Nob Hill Tuesday 3:15PM

97 Do It More Efficiently

98 Resource Management Properties Responsiveness Efficiency

99 Resource Management Properties Responsiveness Efficiency CPU Scheduler Priority I/O Priority

100 Resource Management Properties Responsiveness Efficiency CPU Scheduler Priority Timer Coalescing I/O Priority Throughput/Efficiency CPU Hints

101 Quality of Service Classes UI User Interactive Main thread, animations IN User Initiated Immediate results UT Utility Long-running tasks BG Background Not user visible

102 Choosing a QoS Class UI User Interactive Is this work actively involved in updating the UI? e.g., main thread, animations, input event processing IN User Initiated Is this work required to continue user interaction? e.g., loading active content UT Utility Is the user aware of the progress of this work? e.g., long-running jobs with progress indicators BG Background Can this work be deferred to a better time? e.g., if so, use NSBackgroundActivityScheduler

103 Choosing a QoS Class UI User Interactive Is this work actively involved in updating the UI? e.g., main thread, animations, input event processing IN User Initiated Is this work required to continue user interaction? e.g., loading active content UT Utility Is the user aware of the progress of this work? e.g., long-running jobs with progress indicators BG Background Can this work be deferred to a better time? e.g., if so, use NSBackgroundActivityScheduler

104 Choosing a QoS Class UI User Interactive Is this work actively involved in updating the UI? e.g., main thread, animations, input event processing IN User Initiated Is this work required to continue user interaction? e.g., loading active content UT Utility Is the user aware of the progress of this work? e.g., long-running jobs with progress indicators BG Background Can this work be deferred to a better time? e.g., if so, use NSBackgroundActivityScheduler

105 Choosing a QoS Class UI User Interactive Is this work actively involved in updating the UI? e.g., main thread, animations, input event processing IN User Initiated Is this work required to continue user interaction? e.g., loading active content UT Utility Is the user aware of the progress of this work? e.g., long-running jobs with progress indicators BG Background Can this work be deferred to a better time? e.g., if so, use NSBackgroundActivityScheduler

106 Choosing a QoS Class UI User Interactive Is it okay for User Interactive work to happen before my work? IN User Initiated Is it okay for this work to compete with other User Initiated work? UT Utility Is it okay for my work to take precedence over Utility work? BG Background

107 Choosing a QoS Class UI User Interactive Is it okay for User Interactive work to happen before my work? IN User Initiated Is it okay for this work to compete with other User Initiated work? UT Utility Is it okay for my work to take precedence over Utility work? BG Background

108 Choosing a QoS Class UI User Interactive Is it okay for User Interactive work to happen before my work? IN User Initiated Is it okay for this work to compete with other User Initiated work? UT Utility Is it okay for my work to take precedence over Utility work? BG Background

109 Effects of QoS Background

110 Effects of QoS User Initiated Background

111 Effects of QoS User Initiated Background

112 Effects of QoS Power Power Time Time User Initiated Background

113 Adoption Case Study PhotoMeister 3000 Search Converting (10/100) RAW Images

114 Adoption Case Study PhotoMeister 3000 Search User Interactive Main Thread (automatic) Converting (10/100) RAW Images

115 Adoption Case Study PhotoMeister 3000 Search User Interactive Main Thread (automatic) User Initiated Thumbnail generation Image load (on click) Converting (10/100) RAW Images

116 Adoption Case Study PhotoMeister 3000 Search User Interactive Main Thread (automatic) User Initiated Thumbnail generation Image load (on click) Utility Image import and conversion Converting (10/100) RAW Images

117 Adoption Case Study PhotoMeister 3000 Search User Interactive Main Thread (automatic) User Initiated Thumbnail generation Image load (on click) Utility Image import and conversion Background Search indexing Converting (10/100) RAW Images

118 Queue Structure Main Thread (User Interactive)

119 Queue Structure Thumbnail Generation NSOperationQueue Main Thread (User Interactive)

120 Queue Structure Thumbnail Generation NSOperationQueue Image Conversion NSOperationQueue Main Thread (User Interactive)

121 NSOperation(Queue) and QoS

122 NSOperation(Queue) and QoS NSOperation and NSOperationQueue now have a qualityofservice property: operation.qualityofservice = NSQualityOfServiceUtility;

123 NSOperation(Queue) and QoS NSOperation and NSOperationQueue now have a qualityofservice property: operation.qualityofservice = NSQualityOfServiceUtility; If set on both the operation and queue, the higher will be used

124 NSOperation(Queue) and QoS NSOperation and NSOperationQueue now have a qualityofservice property: operation.qualityofservice = NSQualityOfServiceUtility; If set on both the operation and queue, the higher will be used If not set, NSOperations will infer a QoS from the environment when possible

125 QoS Application Thumbnail Generation NSOperationQueue Image Conversion NSOperationQueue Main Thread (User Interactive)

126 QoS Application Thumbnail Generation NSOperationQueue User Initiated Image Conversion NSOperationQueue Main Thread (User Interactive)

127 QoS Application Thumbnail Generation NSOperationQueue User Initiated Image Conversion NSOperationQueue Utility Main Thread (User Interactive)

128 QoS Is Not Static The logical QoS of an operation may change over time e.g., when user requests the result of work that s already happening a lower QoS

129 QoS Is Not Static The logical QoS of an operation may change over time e.g., when user requests the result of work that s already happening a lower QoS With NSOperation, the QoS of an operation can be promoted by: Enqueueing a higher QoS operation on the same queue Using adddependency: with a higher QoS operation waituntilfinished: or waituntilalloperationsarefinished: from a higher QoS thread

130 Promotion Image Click Event Main Thread Image Conversion NSOperationQueue Utility

131 Promotion Image Click Event // Find operation for image Main Thread Image Conversion NSOperationQueue Utility

132 Promotion Image Click Event // Find operation for image operation.queuepriority = NSOperationQueuePriorityVeryHigh; Main Thread Image Conversion NSOperationQueue Utility

133 Promotion Image Click Event // Find operation for image operation.queuepriority = NSOperationQueuePriorityVeryHigh; operation.qualityofservice = NSQualityOfServiceUserInitiated; Main Thread Image Conversion NSOperationQueue Utility

134 Promotion Image Click Event // Find operation for image operation.queuepriority = NSOperationQueuePriorityVeryHigh; operation.qualityofservice = NSQualityOfServiceUserInitiated; Main Thread Image Conversion NSOperationQueue Utility

135 Your Turn Feed Reader 9000 Search News! Neat Things! Cats! Kittens! 26 ways Lorem ipsum dolor sit amet, consectetur adipiscing elit. Ut volutpat accumsan tellus, eu imperdiet est elementum sed. Sed tincidunt, nibh ut consectetur posuere, est metus. Mauris in elementum orci, varius est. Sed fringilla velit a vestibulum sagi. Lorem ipsum dolor sit amet, consectetur adipiscing elit. Updating Feeds

136 Your Turn Feed Reader 9000 Search Loading content News! Neat Things! Cats! Kittens! 26 ways Lorem ipsum dolor sit amet, consectetur adipiscing elit. Ut volutpat accumsan tellus, eu imperdiet est elementum sed. Sed tincidunt, nibh ut consectetur posuere, est metus. Mauris in elementum orci, varius est. Sed fringilla velit a vestibulum sagi. Lorem ipsum dolor sit amet, consectetur adipiscing elit. Updating Feeds

137 Your Turn Feed Reader 9000 Search Loading content User Initiated News! Neat Things! Cats! Kittens! 26 ways Lorem ipsum dolor sit amet, consectetur adipiscing elit. Ut volutpat accumsan tellus, eu imperdiet est elementum sed. Sed tincidunt, nibh ut consectetur posuere, est metus. Mauris in elementum orci, varius est. Sed fringilla velit a vestibulum sagi. Lorem ipsum dolor sit amet, consectetur adipiscing elit. Updating Feeds

138 Your Turn Feed Reader 9000 Search Loading content User Initiated Image pre-fetching News! Neat Things! Cats! Kittens! 26 ways Lorem ipsum dolor sit amet, consectetur adipiscing elit. Ut volutpat accumsan tellus, eu imperdiet est elementum sed. Sed tincidunt, nibh ut consectetur posuere, est metus. Mauris in elementum orci, varius est. Sed fringilla velit a vestibulum sagi. Lorem ipsum dolor sit amet, consectetur adipiscing elit. Updating Feeds

139 Your Turn Feed Reader 9000 Search Loading content User Initiated Image pre-fetching Background News! Neat Things! Cats! Kittens! 26 ways Lorem ipsum dolor sit amet, consectetur adipiscing elit. Ut volutpat accumsan tellus, eu imperdiet est elementum sed. Sed tincidunt, nibh ut consectetur posuere, est metus. Mauris in elementum orci, varius est. Sed fringilla velit a vestibulum sagi. Lorem ipsum dolor sit amet, consectetur adipiscing elit. Updating Feeds

140 Your Turn Feed Reader 9000 Search Loading content User Initiated Image pre-fetching Background Fetching new feeds News! Neat Things! Cats! Kittens! 26 ways Lorem ipsum dolor sit amet, consectetur adipiscing elit. Ut volutpat accumsan tellus, eu imperdiet est elementum sed. Sed tincidunt, nibh ut consectetur posuere, est metus. Mauris in elementum orci, varius est. Sed fringilla velit a vestibulum sagi. Lorem ipsum dolor sit amet, consectetur adipiscing elit. Updating Feeds

141 Your Turn Feed Reader 9000 Search Loading content User Initiated Image pre-fetching Background Fetching new feeds Requested by user User Initiated News! Neat Things! Cats! Kittens! 26 ways Lorem ipsum dolor sit amet, consectetur adipiscing elit. Ut volutpat accumsan tellus, eu imperdiet est elementum sed. Sed tincidunt, nibh ut consectetur posuere, est metus. Mauris in elementum orci, varius est. Sed fringilla velit a vestibulum sagi. Lorem ipsum dolor sit amet, consectetur adipiscing elit. Updating Feeds

142 Your Turn Feed Reader 9000 Search Loading content User Initiated Image pre-fetching Background Fetching new feeds Requested by user User Initiated Automatic Utility News! Neat Things! Cats! Kittens! 26 ways Lorem ipsum dolor sit amet, consectetur adipiscing elit. Ut volutpat accumsan tellus, eu imperdiet est elementum sed. Sed tincidunt, nibh ut consectetur posuere, est metus. Mauris in elementum orci, varius est. Sed fringilla velit a vestibulum sagi. Lorem ipsum dolor sit amet, consectetur adipiscing elit. Updating Feeds

143 Your Turn Feed Reader 9000 Search Loading content User Initiated Image pre-fetching Background Fetching new feeds Requested by user User Initiated Automatic Utility Search indexing News! Neat Things! Cats! Kittens! 26 ways Lorem ipsum dolor sit amet, consectetur adipiscing elit. Ut volutpat accumsan tellus, eu imperdiet est elementum sed. Sed tincidunt, nibh ut consectetur posuere, est metus. Mauris in elementum orci, varius est. Sed fringilla velit a vestibulum sagi. Lorem ipsum dolor sit amet, consectetur adipiscing elit. Updating Feeds

144 Your Turn Feed Reader 9000 Search Loading content User Initiated Image pre-fetching Background Fetching new feeds Requested by user User Initiated Automatic Utility Search indexing Background News! Neat Things! Cats! Kittens! 26 ways Lorem ipsum dolor sit amet, consectetur adipiscing elit. Ut volutpat accumsan tellus, eu imperdiet est elementum sed. Sed tincidunt, nibh ut consectetur posuere, est metus. Mauris in elementum orci, varius est. Sed fringilla velit a vestibulum sagi. Lorem ipsum dolor sit amet, consectetur adipiscing elit. Updating Feeds

145 Debugging QoS

146 Debugging QoS Set breakpoints to confirm requested QoS

147 Debugging QoS Set breakpoints to confirm requested QoS Use powermetrics to confirm which QoS is in use

148 Debugging QoS Set breakpoints to confirm requested QoS Use powermetrics to confirm which QoS is in use Use spindump to determine the QoS code is executing with

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154 QoS Accounting % sudo powermetrics --show-process-qos --samplers tasks

155 QoS Accounting % sudo powermetrics --show-process-qos --samplers tasks *** Sampled system activity (Wed May 28 00:03: ) ( ms elapsed) ***! *** Running tasks ***! Name ID CPU ms/s User% MyApplication ! Deadlines (<2 ms, 2-5 ms) Wakeups (Intr, Pkg idle) ! QOS (ms/s) Default Maint BG Util Lgcy U-Init U-Intr

156 QoS Accounting % sudo powermetrics --show-process-qos --samplers tasks *** Sampled system activity (Wed May 28 00:03: ) ( ms elapsed) ***! *** Running tasks ***! Name ID CPU ms/s User% MyApplication ! Deadlines (<2 ms, 2-5 ms) Wakeups (Intr, Pkg idle) ! QOS (ms/s) Default Maint BG Util Lgcy U-Init U-Intr

157 QoS Accounting % sudo powermetrics --show-process-qos --samplers tasks *** Sampled system activity (Wed May 28 00:03: ) ( ms elapsed) ***! *** Running tasks ***! Name ID CPU ms/s User% MyApplication ! Deadlines (<2 ms, 2-5 ms) Wakeups (Intr, Pkg idle) ! QOS (ms/s) Default Maint BG Util Lgcy U-Init U-Intr

158 QoS Accounting % sudo powermetrics --show-process-qos --samplers tasks *** Sampled system activity (Wed May 28 00:03: ) ( ms elapsed) ***! *** Running tasks ***! Name ID CPU ms/s User% MyApplication ! Deadlines (<2 ms, 2-5 ms) Wakeups (Intr, Pkg idle) ! QOS (ms/s) Default Maint BG Util Lgcy U-Init U-Intr

159 Sampling QoS % sudo spindump -timeline MyApplication

160 Sampling QoS! % sudo spindump -timeline MyApplication Thread 0x6bb7a DispatchQueue samples (1-1000) priority cpu time 1.488s <thread QoS utility, priority 20> 1000 start_wqthread + 13 (libsystem_pthread.dylib ) [0x7fff82e73a01] _pthread_wqthread (libsystem_pthread.dylib ) [0x7fff82e75bd1] _dispatch_worker_thread (libdispatch.dylib ) [0x10002fa29] _dispatch_root_queue_drain (libdispatch.dylib ) [0x ] [AppDelegate applicationdidfinishlaunching:]_block_invoke (AppDelegate.m:25 in MyApplication ) [0x e5] 1-4 <thread QoS background> 2 45-[AppDelegate applicationdidfinishlaunching:]_block_invoke (AppDelegate.m:28 in MyApplication ) [0x e5] 1-4

161 Sampling QoS! % sudo spindump -timeline MyApplication Thread 0x6bb7a DispatchQueue samples (1-1000) priority cpu time 1.488s <thread QoS utility, priority 20> 1000 start_wqthread + 13 (libsystem_pthread.dylib ) [0x7fff82e73a01] _pthread_wqthread (libsystem_pthread.dylib ) [0x7fff82e75bd1] _dispatch_worker_thread (libdispatch.dylib ) [0x10002fa29] _dispatch_root_queue_drain (libdispatch.dylib ) [0x ] [AppDelegate applicationdidfinishlaunching:]_block_invoke (AppDelegate.m:25 in MyApplication ) [0x e5] 1-4 <thread QoS background> 2 45-[AppDelegate applicationdidfinishlaunching:]_block_invoke (AppDelegate.m:28 in MyApplication ) [0x e5] 1-4

162 Sampling QoS! % sudo spindump -timeline MyApplication Thread 0x6bb7a DispatchQueue samples (1-1000) priority cpu time 1.488s <thread QoS utility, priority 20> 1000 start_wqthread + 13 (libsystem_pthread.dylib ) [0x7fff82e73a01] _pthread_wqthread (libsystem_pthread.dylib ) [0x7fff82e75bd1] _dispatch_worker_thread (libdispatch.dylib ) [0x10002fa29] _dispatch_root_queue_drain (libdispatch.dylib ) [0x ] [AppDelegate applicationdidfinishlaunching:]_block_invoke (AppDelegate.m:25 in MyApplication ) [0x e5] 1-4 <thread QoS background> 2 45-[AppDelegate applicationdidfinishlaunching:]_block_invoke (AppDelegate.m:28 in MyApplication ) [0x e5] 1-4

163 Quality of Service Specify the responsiveness and energy requirements of work Available in both Foundation and C APIs Classify long-running or resource-intensive operations in your existing code Aim for >90% of time at Utility or below when the user is inactive

164 Related Session Power, Performance, and Diagnostics: What s New in GCD and XPC Russian Hill Thursday 2:00PM

165 Do It Less

166 Use Less CPU Graphics Storage

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170 Reduce CPU Use 1% CPU 10% CPU 100% CPU

171 Reduce CPU Use 1% CPU 10% higher power draw 10% CPU 100% CPU

172 Reduce CPU Use 1% CPU 10% higher power draw 10% CPU 2x power draw 100% CPU

173 Reduce CPU Use 1% CPU 10% higher power draw 10% CPU 2x power draw 100% CPU 10x power draw

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178 Performance Unit Tests

179 Performance Unit Tests Additions to XCTestCase API in Xcode 6

180 Performance Unit Tests Additions to XCTestCase API in Xcode 6 Helps you find performance regressions

181 Performance Unit Tests Additions to XCTestCase API in Xcode 6 Helps you find performance regressions! - (void)testsomething { [self measureblock:^{ //...snip.. }]; }

182 Related Sessions Testing in Xcode 6 Marina Thursday 9:00AM Continuous Integration with Xcode 6 Marina Thursday 2:00PM

183 Reduce CPU Use

184 Reduce CPU Use CPU use has a huge dynamic range in power

185 Reduce CPU Use CPU use has a huge dynamic range in power Monitor CPU use with Xcode debug gauge

186 Reduce CPU Use CPU use has a huge dynamic range in power Monitor CPU use with Xcode debug gauge Profile with Instruments

187 Reduce CPU Use CPU use has a huge dynamic range in power Monitor CPU use with Xcode debug gauge Profile with Instruments Prevent regressions with performance unit tests

188 Minimize Timers

189 Minimize Timers -[NSObject performselector:withobject:afterdelay:] pthread_cond_timedwait() CFRunLoopTimer NSTimer Grand Central Dispatch timers sleep() select() CVDisplayLink dispatch_semaphore_wait()

190 Timer Fixed Cost Power Time

191 Timer Fixed Cost Timer Firings Power Time

192 Timer Fixed Cost Timer Firings Power Time

193 Timer Fixed Cost Timer Firings Power Time

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197 Diagnosing Timer Issues timerfires $ sudo timerfires -p MyApplication -s -g

198 Diagnosing Timer Issues timerfires $! sudo timerfires -p MyApplication -s -g COUNT PID PROCESS TYPE TIMER ROUTINE MyApp dispatch MyApp`-[AppModel updatewidgets:] MyApp CF MyApp`-[AppDelegate timerfired:] MyApp sleep libsystem_kernel.dylib` semwait_signal+0xa libsystem_c.dylib`usleep+0x36 MyApp`-[AppModel pollforchange]+0x1a libdispatch.dylib`_dispatch_call_block_and_release+0xc

199 Timer Coalescing Time

200 Timer Coalescing Time

201 Specify Timer Tolerance

202 Specify Timer Tolerance [mytimer settolerance:60.0];! CFRunLoopTimerSetTolerance(myTimer, 60.0);! dispatch_source_set_timer(my_timer, DISPATCH_TIME_NOW, 30 * NSEC_PER_SEC, 60 * NSEC_PER_SEC);

203 Minimize Timers Be mindful of wakeup overhead Monitor for wakeups Debug with timerfires Specify timer tolerance

204 Related Session Energy Best Practices WWDC 2013

205 Efficient Graphics

206 Efficient Graphics

207 Efficient Graphics

208 Efficient Graphics

209 Efficient Graphics

210 Limit Screen Updates Avoid extraneous screen updates Unnecessary drawing kicks graphics hardware out of low-power modes Drawing more content than needed causes extra power draw to update the screen Use needstodrawrect: or getrectsbeingdrawn:count: methods to fine-tune drawing

211 Flash Screen Updates

212 Flash Screen Updates

213 Flash Screen Updates Graphics Tools for Xcode:

214 Flash Screen Updates Core Animation

215 Visual Effects Translucent blurs have an energy cost Avoid placing over updating elements

216 Visual Effects Translucent blurs have an energy cost Avoid placing over updating elements NSVisualEffectView App

217 Visual Effects Translucent blurs have an energy cost Avoid placing over updating elements NSVisualEffectView Animating Content App

218 Visual Effects Translucent blurs have an energy cost Avoid placing over updating elements NSVisualEffectView Animating Content App

219 Efficient Graphics Draw minimally and efficiently Monitor drawing with Quartz Debug or Instruments Avoid blurs on updating content

220 Flash Power Writes to Flash are much more energy hungry than reads Write the minimum content necessary Do writes in aggregate for better power efficiency

221 Flash Power Writes to Flash are much more energy hungry than reads Write the minimum content necessary Do writes in aggregate for better power efficiency Any I/O will pull device out of low-power states Use caching to your advantage

222 Do It Less Profile and monitor CPU Reduce timers Be efficient in the use of graphics Minimize I/O

223 Summary Improving your app s energy consumption improves user experience

224 Summary Improving your app s energy consumption improves user experience Continuously monitor your app s energy and resource consumption

225 Summary Improving your app s energy consumption improves user experience Continuously monitor your app s energy and resource consumption Look for ways to Do it never Respond to changes in active state

226 Summary Improving your app s energy consumption improves user experience Continuously monitor your app s energy and resource consumption Look for ways to Do it never Respond to changes in active state Do it at a better time Let the system schedule work

227 Summary Improving your app s energy consumption improves user experience Continuously monitor your app s energy and resource consumption Look for ways to Do it never Respond to changes in active state Do it at a better time Let the system schedule work Do it more efficiently Specify Quality of Service Classes on your work

228 Summary Improving your app s energy consumption improves user experience Continuously monitor your app s energy and resource consumption Look for ways to Do it never Respond to changes in active state Do it at a better time Let the system schedule work Do it more efficiently Specify Quality of Service Classes on your work Do it less Optimize and improve your resource use

229 Summary Improving your app s energy consumption improves user experience Continuously monitor your app s energy and resource consumption Look for ways to Do it never Respond to changes in active state Do it at a better time Let the system schedule work Do it more efficiently Specify Quality of Service Classes on your work Do it less Optimize and improve your resource use And stick around for Part 2

230 More Information Paul Danbold Core OS Evangelist Energy Best Practices WWDC 2013 Building Resource Efficient Apps WWDC 2013 Apple Developer Forums

231 Related Sessions What s New in Foundation Networking Nob Hill Tuesday 3:15PM Improving Your App with Instruments Marina Tuesday 4:30PM Writing Energy Efficient Code, Part 2 Russian Hill Wednesday 11:30AM Testing in Xcode 6 Marina Thursday 9:00AM Fix Bugs Faster Using Activity Tracing Russian Hill Thursday 11:30AM Continuous Integration with Xcode 6 Marina Thursday 2:00PM Power, Performance, and Diagnostics: What s New in GCD and XPC Russian Hill Thursday 2:00PM

232 Labs Power and Performance Lab Core OS Lab B Wednesday 2:00PM Instruments Lab Tools Lab B Thursday 9:00AM Power and Performance Lab Core OS Lab A Thursday 3:15PM

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