Velocity 2012 - Taming the Mobile BeastPresentation Transcript
Taming theMobile BeastPatrick Meenan Matt Welsh@patmeenan @mdwelsh http://www.flickr.com/photos/nao-cha/2660459899/Google, Inc. Google, Inc.
Mobile is huge!2.25B Global Internet Users 1.1B Mobile Users Source: UN/ITU internetworldstats.com
For many, a mobile device is the only way to access the Internet Mobile-Only Country Internet Users Egypt 70% India 59% South Africa 57% Indonesia 44% United States 25% Source: OnDevice Researchhttp://www.flickr.com/photos/43560604@N03/6845754798/
... and growing with respect to desktop
Desktop Web Performance Optimization
Mobile Web Performance Optimization
What well cover today: Getting a handle on mobile web performance How to collect measurements on mobile devices Deep dive into mobile web performance issues and common gotchas Using Chrome for Androids remote debugger Mobile bookmarklets and other tools
Measurement Tools
Mobitest - www.blaze.io/mobile/
WebPageTest - www.webpagetest.org Web Page Test nowsupports Android and iOS!
Waterfall Basics
Waterfall Components
Waterfalls as seen by HARViewer DNS TCP Waiting Receiving Lookup Connect for response response
Studying Mobile Waterfalls
Visualizing a mobile website load (brown.edu) 75 seconds!
brown.edus mobile home page124 KB, 1800x800background image that is completely obscured
The web was not designed for mobile Huge disparity between modern web design and mobile devices... ● Increasingly rich content ● Highly dynamic pages ● Large amount of JavaScript to manipulate the page, perform asynchronous work, fetch new content ● 3D acceleration, animations, complex graphics ... all sent using a crufty, somewhat broken protocol (HTTP) The web is not just <b>plain</b> <i>old</i> <blink>HTML</blink> anymore - it is a complete application platform.
Here Be Dragons● Making a mobile connection: Radio Resource Control● Browser connection limits● HTTP Pipelining● Caching: Browsers vs. embedded HTTP libraries● Carrier network proxying● JavaScript execution time differences
Making a Mobile Connection
Typical Mobile Network Performance Country Average RTT Average Downlink Average Uplink Throughput Throughput South Korea 278 ms 1.8 Mbps 723 Kbps Vietnam 305 ms 1.9 Mbps 543 Kbps US 344 ms 1.6 Mbps 658 Kbps UK 372 ms 1.4 Mbps 782 Kbps Russia 518 ms 1.1 Mbps 439 Kbps India 654 ms 1.2 Mbps 633 Kbps Nigeria 892 ms 541 Kbps 298 Kbps Compare to typical desktop and WiFi performance: < 50 ms RTT, 5 Mbps throughput in the US Source: Ookla/Speedtest.net
Typical Mobile Network Performance Country Average RTT Average Downlink Average Uplink Throughput Throughput South Korea 278 ms 1.8 Mbps 723 Kbps Vietnam 305 ms 1.9 Mbps 543 Kbps US 344 ms 1.6 Mbps 658 Kbps UK 372 ms 1.4 Mbps 782 Kbps Russia 518 ms 1.1 Mbps 439 Kbps India 654 ms 1.2 Mbps 633 Kbps Nigeria 892 ms 541 Kbps 298 Kbps Things are changing fast! LTE promises < 100 ms RTT, 50+ Mbps downlink Source: Ookla/Speedtest.net
Bandwidth Impact 3G LTE 20 Top sites measured in October, 2011
Latency Impact 3G LTE DSL/ Dial 20 Top sites measured in October, 2011 Cable
Making a Radio ConnectionBefore a cellular device can transmit or receive data, it has toestablish a radio channel with the network. This can take several seconds!Also, if no data is transmitted or received after a timeout,the channel goes idle, requiring a new channel to be established.This behavior can wreak havoc on web page load times.
Probing the Radio State MachineTry this sometime:Build a webpage that loads a small (1KB) image at increasingintervals. Watch how long it takes to load.
Probing the Radio State MachineTry this sometime:Build a webpage that loads a small (1KB) image at increasingintervals. Watch how long it takes to load.Heres what it looks like on WiFi: Every image loads in ~120 ms
The same thing on T-Mobile: 1 sec delay 2 sec delay 3 sec delay 4 sec delay 5 sec delay
The same thing on T-Mobile: Between 2 and 3 sec, huge increase in load time
Example 3G Radio Resource Control State Machine No radio connection Idle for 12 sec CELL_ IDLE FACH Buffer size > threshold Shared radio channel Transmit data Delay: 1-2 sec Idle for 5 sec CELL_ DCH The exact delays and idle timeouts depend on the carrier, which equipment they have installed, and Dedicated how it is configured. radio channel This depends on the network, not the device.Run your own test now! http://goo.gl/F5sKV Data from: http://www.eecs.umich.edu/~fengqian/paper/aro_mobisys11.pdf
Browser Connection Limits
Browser Connection LimitsThe number of parallel connections varies tremendously acrossmobile browsers.brown.edu on Android 2.3.5 Gingerbread: Total of 4 parallel connections
Browser Connection LimitsThe number of parallel connections varies tremendously acrossmobile browsers.brown.edu on Android 4.0.4 Ice Cream Sandwich: Looks like 6 connections per domain
Browser Connection LimitsThe number of parallel connections varies tremendously acrossmobile browsers.brown.edu on iOS 5: Looks like a lot of parallelism
Browser Connection LimitsThe number of parallel connections varies tremendously acrossmobile browsers.brown.edu on Chrome for Android: Also 6 connections per domain
Browser Connection Limits - Summary Browser Connections Per Domain Total Connections Android pre-Honeycomb 4 4 Android post-Honeycomb 6 256 iOS 4 4 30 iOS 5 6 52 Chrome for Android 6 256Caveats: It takes a lot of experimentation and probing to get someof these numbers. iOS results, in particular, should be taken with agrain of salt.
Are more connections always better?Parallel TCP connections are typically used for two purposes: 1) Saturate the network 2) Avoid head-of-line blockingOn 3G, more connections are not always a good idea: - Each connection pays the cost of the TCP handshake (200+ ms on typical 3G links) - Parallel connections can adversely compete for the channel
HTTP Pipelining
HTTP Pipelining Been in the spec since HTTP/1.1, but largely ignored by desktop browser vendors Originally thought it would break the InternetAndroid 2.3.4 (Gingerbread)Android Browser has been using pipelining for a long time! Several requests withMobile Safari on iOS 5 is using it now, too. identical start times, staggered completion timesAndroid ICS and Chrome do not use pipelining, however.
Carrier Network Proxies
Carrier network proxiesMost large carriers do transparent web proxyingSimple page with a 1MB JavaScript file, loaded over WiFi: 976KB, as expected
Carrier network proxiesMost large carriers do transparent web proxyingSimple page with a 1MB JavaScript file, loaded over WiFi: 976KB, as expectedThe same page, loaded on T-Mobile UMTS: 7.6KB !?!?!?!! T-Mobiles proxy uses gzip!
JavaScript Execution Time
JavaScript Execution TimeJavaScript is typically a lot slower on mobile devices. SunSpider benchmark results:Dual Core Mac Pro: 266.1 msGalaxy Nexus (stock browser): 1899 msGalaxy Nexus (Chrome): 1574 msiPhone 3GS (iOS 5): 4737 msiPhone 4S (iOS 5): 2200 msiPad 2 (iOS 5): 2097 ms
Browser Caching Behavior
Not all caches are created equalMobile browsers have small caches:Android 2.3: 8 MBiOS 5: 100 MB, but not persistent!Android Chrome: 250 MBCompare to typical size of 512 MB or more for desktop browsers.
Browsers != Embedded HTTP LibrariesCommon embedded HTTP libraries often have broken cachebehavior!java.net.URLConnectionjava.net.HttpURLConnectionorg.apache.http.client.HttpClient None of these do any caching at all.android.webkit.WebView Does caching, but does not support redirection.NSURLRequest - iOS5 Does caching, but total cache size is 1 MB for small objects, 40 MB for large objects, no caching for objects > 2MB. Web Caching on Smartphones: Ideal vs. Reality by Feng Qian, Kee Shen Quah, Junxian Huang, Jeffrey Erman, Alexandre Gerber, Z. Morley Mao, Subhabrata Sen, and Oliver Spatscheck, Proceedings of ACM Mobisys 2012.
SummaryMobile networks have high round-trip-times: hundreds of ms.Mobile connections can take several seconds to get established.HTTP pipelining: Coming to iOS, going away in Android.Beware carrier network proxies.JavaScript: Aint so fast.Not all mobile caches are created equal.
Roadmap Getting a handle on mobile web performance How to collect measurements on mobile devices Deep dive into mobile web performance issues and common gotchas Using Chrome for Androids remote debugger Mobile bookmarklets and other tools
Remote DebuggingChrome on Android
Remote Debugging Chrome on AndroidChrome on Android has full support for Chrome Developer Tools Desktop Chrome USB tethering
Getting Started1) Fire up Chrome on your device2) Settings > Developer Tools > Enable USB Web debugging
Getting Started3) On desktop, run: adb forward tcp:9222 localabstract:chrome_devtools_remote4) On desktop, visit: http://localhost:9222
Getting Started5) Pick the tab you want to debug:
Getting Started6) Youll initially see a blank window:
Getting Started7) Hit reload on the phone to get a timeline:
So what can you do with this?Anything you can do with Chrome Dev Tools on desktop! ● Network events timeline ● Inspect and manipulate the DOM ● Profile CPU and memory usage ● Performance audit
Network events timelineEach resource is one line Timeline Size, type, time DOMContent onload event event
Exploring a single request / response Request Headers Response headers
Exploring the DOM Mouse over a DOM element Element is highlighted on device!
CPU and memory profiling
CPU and memory profiling CPU profile of each JS function
CPU and memory profiling Timeline of page memory usage Timeline of page events Size of DOM, #event listeners
SummaryChrome for Android gives you tremendous visibility and controlthrough its remote debugging interface.Inspect and control the DOM, get timeline information, CPU andmemory profiling, and more.iOS6 is introducing Remote Debugging for Mobile Safari! http://bit.ly/L1zXTX Very similar interface and functionality.
Mobile Bookmarklets
Meta Bookmarklet http://stevesouders.com/mobileperf/mobileperfbkm.php
Firebug Lite http://getfirebug.com/firebuglite#Stable
Measuring mobile web behavior is hard! Most mobile browsers have no instrumentation interface. But, things are improving: Chrome for Android and Mobile Safari in iOS6 have a rich debug interface (more later!) Web Page Test and Blaze.io mobile agents use clever tricks: - Use embedded WebView components, not real browsers - On Android: run tcpdump to capture network packets - On iOS: Instrument pages using JavaScript Caveat: - Not all events available on iOS (e.g., no DNS lookup or TCP connect times)
Know WHAT and HOW you are measuringKnow thy Browser● Real Device ○ Native Browser ○ App with embedded UIWebView● Simulator● Changed User-Agent String in Desktop BrowserGroketh thy Connectivity● Carrier Network ○ Which Carrier ○ Carrier Rewriting Proxies● WiFi ○ Connected to....?
TakeawaysDecide what and how you want to measureMobile performance deeply impacted by network and browser architectureMobile measurement tools have their limits, but are maturing rapidlyThis stuff is hard, but its an exciting time to be alive!
Google Booth - TalksTuesday, June 26 - Morning Break 10:15 – 10:30 : Site Speed Reports in Google Analytics: Measuring your website’s performance Afternoon Break 3:10 – 3:25 : Measuring user perceived latency with Google Analytics Site Speed reports: hands-on demo and insights 3:30 – 3:45 : Async Scripts and why you care, particularly for third-party contentWednesday, June 27th - Morning Break 10:00 – 10:15 : PageSpeed Automatic Optimizations 10:15 – 10:30 : PageSpeed Insights for Chrome with mobile support – Demo Afternoon Break 3:10pm – 3:25pm : Measuring Web Performance 3:30pm – 3:45pm : HTTP Streaming – discuss the true latency bottleneck with bi-directional HTTP streaming and “full-duplex HTTP”
Google Booth - Office HoursTuesday, June 25 - Morning Break 10:30 - 10:30 : Q&A: Mobile Web Measurement with Matt and PatTuesday, June 26 - Afternoon Break 3:10 – 3:50 : Q&A: Your Chrome Wishlist, Suggestions and QuestionsWednesday, June 27 - Morning Break 10:00 – 10:30 : Q&A: Performance monitoring with Google Analytics
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