Quantifying The Mobile Difference

The Mobile Difference – In NumbersGuy Podjarny@guypodhttp://www.guypo.com/ Akamai Confidential

Mobile Isn’t Desktop•  It’s different in many ways…•  This presentation focuses on sizing the gap •  How big is the gap between Mobile & Non-Mobile? •  How much does it impact performance?•  We can’t cover everything, so we’ll focus on three topics: •  Mobile CPU != Desktop/Laptop CPU •  Cellular Networks != Broadband Networks •  Mobile Browsers != Desktop Browsers Faster ForwardTM ©2012 Akamai

Mobile Computing Power !=Desktop/Laptop Computing Power Akamai Confidential

Perf of iOS5 across different hardware SunspiderJSBenchmark,iOS5Devices 10x 24yroldMBP,2x2.7Ghz 230 Better iPhone4S,2x800Mhz 2250 37% Better iPhone4,800Mhz 3545 25% Better iPhone3GS,600Mhz 4737 0" 500" 1000" 1500" 2000" 2500" 3000" 3500" 4000" 4500" 5000" Faster ForwardTM ©2012 Akamai

Test Time!•  Question: Does mobile computing power impact page load time?•  Tested Sites: Alexa US Top 100•  Test Tool: Mobitest•  Details: •  Test iPhone 4, iPhone 4S and iOS Simulator on 2-yr old MacBook Pro •  Note: iOS Simulator uses the actual hardware •  Tested overnight •  High speed Cable connection, WiFi Faster ForwardTM ©2012 Akamai

Results: Hardware Load Time Impact Sunspider*&*Load*Time*Per*Device* 4000" 3500" 3000" 2500" Sunspider" 2000" Load"Time" 1500" 1000" 500" 0" iPhone"4,"800"Mhz" iPhone"4S,"2x800"Mhz" 24yr"old"MBP,"2x2.7"Ghz" iPhone 4 iPhone 4S Measure vs. vs. iPhone 4S iOS Simulator Sunspider 37% 90% Load Time 15% 48% Faster ForwardTM ©2012 Akamai

CPU Difference - Conclusions•  Mobile CPU is still underpowered compared to desktop•  It indeed impacts web performance, even for regular sites•  Impact on load time is lighter than on benchmarks •  Roughly 25-50% of impact on benchmarks•  Computing power is more than just CPU •  At least GPU and RAM also have an impact •  Stick around for Ariya’s Presentation!•  Recommendation: Test on old devices too Faster ForwardTM ©2012 Akamai

Cellular Network !=Broadband Network Akamai Confidential

Cellular Network Speed – WikipediaProtocol Max Downlink Max UplinkGPRS 56-115 KbpsCDMA200 (1X) 153.6 KbpsEdge 236.8 Kbps3G Bar 2 Mbps stationary client 384 Kbps moving clientEV-DO 2.5-4.9 Mbps 0.15-1.8 MbpsEDGE Evolution 1.6 Mbps 0.5 MbpsHSDPA 2 Mbps 200 KbpsHSPA+ 14.4 Mbps4G Bar 1 Gbps stationary client 100 Mbps moving clientHSPA+ Release 11 21-672 Mbps 5.8-168 MbpsLTE 100-300 Mbps 50-75 MbpsWiMax 37-365 Mbps 17-376 Mbps Faster ForwardTM ©2012 Akamai

PCWorld/Novarum •  3G •  Download: 0.59 – 3.84 Mbps •  Upload: 0.56 – 1.44 Mbps •  4G •  Download: 2.81 – 9.12 Mbps •  Upload: 0.97 – 5.86 Mbps •  Date: Apr, 2012Source (PCWorld): http://bit.ly/JX7MQw Faster ForwardTM ©2012 Akamai

Cellular Network Speed – Conclusions•  Theoretical limits are NOT the reality•  Cellular bandwidth definitely less than broadband•  There is no single number for cellular network speed•  But we need SOME numbers for testing…•  So here’s a SWAG at numbers to use for testing •  Merging many data points, and rounding numbers for convenience Test Case Download (Kbps) Upload (Kbps) Poor Cell Network 400 250 Average Cell Network 1200 600 Faster ForwardTM ©2012 Akamai

Broadband Latency (FCC) “Fiber-to-the-home services provided 17 ms round-trip latency on average, while cable-based services averaged 28 ms, and DSL-based services averaged 44 ms.” Connection RTT Type Fiber 17ms Cable 28ms DSL 44ms Faster ForwardTMhttp://www.fcc.gov/measuring-broadband-america ©2012 Akamai

Ofcom study, UK Mobile Networks, May ‘11 “Latency… was an average of 117 milliseconds. Nearly two Static Tests: thirds of tests took more than 100 milliseconds” User Panel: “Average latency was 192 milliseconds and around a third of tests delivered latency of higher than 200 milliseconds”http://stakeholders.ofcom.org.uk/binaries/research/telecoms-research/bbspeeds2010/Mobile_BB_performance.pdf Faster ForwardTM ©2012 Akamai

Yep, Mobile Latency is different Latency(by(Connec,on(Type(•  Chart showing latency on Mobile vs Broadband, Ofcom 350" numbers 300" 250" 200" 150" 100" 50" 0" Fiber" Cable" DSL" Mobile" Mobile" Mobile" Mobile" (Ofcom"Tests)" (Ofcom" (Cisco)" Consumer" Panel)" (Cisco)" Faster ForwardTM ©2012 Akamai

Cellular Network Latency - Conclusions•  Not a pretty sight…•  MUCH higher than broadband latency•  Measured averages around 100-300 ms•  Updated table for suggested testing numbers: Test Case Download Upload Latency (Kbps) (Kbps) (ms) Poor Cell Network 500 250 300 Average Cell Network 1200 600 200 Faster ForwardTM ©2012 Akamai

Test Time!•  Question: How much impact does the difference in Bandwidth & Latency have on web performance?•  Tested Sites: Alexa US Top 100•  Test Tool: WebPageTest•  Details: •  Increase Latency, Download & Upload Bandwidth separately •  Set no limits on other two variables •  Run each test 3 times, use median result Faster ForwardTM ©2012 Akamai

Bandwidth/Latency Difference - Conclusions•  Upload difference doesn’t matter much•  Download difference DOES matter•  Latency difference matters the most•  Tip #1: Test using Cell Network speeds •  Know what you’re getting•  Tip #2: Reduce number of requests •  Especially blocking requests, e.g scripts, CSS•  Tip #3: Reduce number of bytes Faster ForwardTM ©2012 Akamai

Packet Loss, Akamai/MIT Research •  Tested 149 Million connections in 51 countries •  Compared PL for mobile networks from non-mobile networks •  Most connections have no packet loss (Median PL is 0%). •  75th percentile usually zero too •  Average connection packet loss: 2.5% •  Fixed network average is 2.2% •  Implies connections are usually fine, but sometimes terrible •  The average PL for the non-zero half is 5% •  Suggests “small” connections have higher Packet Loss •  HTTP Connections are often smallhttp://pam2012.ftw.at/papers/PAM2012paper6.pdf Faster ForwardTM ©2012 Akamai

Packet Loss - Conclusions•  Packet Loss is significantly higher in Mobile, But… •  It’s small (even in Mobile) •  It usually doesn’t happen (even in Mobile)•  Smaller connections lose more packets•  Recommendations: •  Don’t worry about Packet Loss too much… •  Include some Packet Loss in your tests •  Ideal: Lots of caching, good user-feedback on error and no SPOFs SWAG Test Case Download Upload Latency Packet (Kbps) (Kbps) (ms) Loss Poor Cell Network 500 250 300 1% Average Cell Network 1200 600 200 0% Faster ForwardTM ©2012 Akamai

Different Carriers have different average speedsSource (PCWorld): http://bit.ly/JX7MQw Source: Ofcom http://stakeholders.ofcom.org.uk/binaries/research/telecoms-research/bbspeeds2010/Mobile_BB_performance.pdf Faster ForwardTM ©2012 Akamai

Volatility - Conclusions•  Stop Guessing! •  You can’t predict your user’s speeds, today or in the future•  Little value in doing something “only on cellular”•  Strategy #1: Aim at the lowest common denominator •  Design for a usable experience in a slow network •  Enhance the page when possible•  Strategy #2: Adapt to Network Conditions •  E.g. reduce image quality when conditions are bad •  Not easy to do, but doable •  Check your options with your Server/Host/CDN Faster ForwardTM ©2012 Akamai

Cellular Networks - Summary•  Cellular Networks are kinda crappy •  Can’t live with ‘em, can’t live without ‘em…•  You can assume latency will be high •  And download won’t be too awesome•  Don’t worry about Packet Loss & Upload rate •  You have bigger things to worry about•  Make Peace with it – you can’t predict cellular network speed •  Best bet is to aim low, and adapt to network conditions SWAG Test Case Download Upload Latency Packet (Kbps) (Kbps) (ms) Loss Poor Cell Network 500 250 300 1% Average Cell Network 1200 600 200 0% Faster ForwardTM ©2012 Akamai

Mobile Browser !=Desktop Browser Akamai Confidential

Actually, they’re not that different…•  Mobile & Desktop browsers are actually similar•  Many share the same underlying engines (e.g. WebKit)•  Some share the browser itself (e.g. Safari, Chrome, Firefox)•  How are they different, then? •  HTTP Pipelining •  Connection Models •  Cache Sizes •  Fragmentation Faster ForwardTM ©2012 Akamai

Mobile Software: Pipelining •  HTTP Pipelining is around since HTTP 1.1 •  Send multiple requests on connection before receiving response •  Most useful in high latency environment •  Big in Mobile •  All big mobile browsers • iOS 5+, Android, Opera •  Hardly used on Desktop • Opera Only (Default) • Chrome, Firefox (Opt-in)49 Faster ForwardTM ©2012 Akamai

Network Capture•  Samsung Galaxy S •  Max Conn: 12 •  Conn Per Host: 12 •  Max Piped Reqs: 6 •  Max “In-Flight” Reqs: 72 (!!!)•  Full Details: http://www.guypo.com/technical/http-pipelining- request-distribution-algorithms/50 Faster ForwardTM ©2012 Akamai

Test Time!•  Question: Does HTTP Pipelining help make websites faster?•  Tested Sites: Alexa US Top 500•  Test Tool: WebPageTest•  Details: •  Use Firefox agent, which supports pipelining •  Turn pipelining on and off •  Set bandwidth to DSL, Cable & FIOS •  Increase Latency to see if impact changes Faster ForwardTM ©2012 Akamai

Test Results – Pipelining has little effect… Pipelining"Off" Pipelining"Off"Load%Time,%DSL%Bandwidth% Pipelining"On" Load%Time,%Cable%Bandwidth% Pipelining"On"14,000"12,000" 10,000"10,000" 8,000" 8,000" 6,000" 6,000" 4,000" 4,000" 2,000" 2,000" 0" 0" 50" 100" 200" 300" 50" 100" Pipelining"Off" Load%Time,%FIOS%Bandwidth% Pipelining"On" 12,000" 10,000" 8,000" 6,000" 4,000" 2,000" 0" 50" 100" 200" 300" Faster ForwardTM ©2012 Akamai

Why doesn’t pipelining have an effect?•  Are you sure pipelining was used? •  Yes… confirmed via tcpdump and various other metrics•  I don’t know for sure, but I can guess… •  18 domains referenced on a page (average) •  9 domains used only for one request (average) •  3-4 domains used only for two requests (average) •  Browsers prefer new connection to piping a request •  Other bottlenecks…•  Saw similar results for SPDY in recent test •  Details: http://bit.ly/MptaBV•  Conclusion: Not much you can/should do… Faster ForwardTM ©2012 Akamai

Summary Akamai Confidential

Summary•  Those were A LOT of numbers…•  Mobile is truly different, and it matters for web performance •  Who saw that coming?!•  Main differences for Web Performance: •  CPU delta, but its effect is not linear •  Network delta in Latency & Download BW, not upload/Packet-Loss•  Main takeaways for web developers: •  Test performance on old devices too •  Test with at least average and poor cell network performance •  Provide a decent experience in the worst of conditions•  Remember - we only looked at a handful of aspects… Faster ForwardTM ©2012 Akamai

Thank You! Questions? The Mobile Difference – In NumbersGuy Podjarny@guypodhttp://www.guypo.com/ Akamai Confidential

http://econsultancy.com	3072
http://www.iphone-entreprise.com	392
http://lanyrd.com	29
http://us-w1.rockmelt.com	21
http://apps.synaptive.net	17
http://eventifier.co	11
http://translate.googleusercontent.com	9
https://twitter.com	8
http://www.hanrss.com	5
http://core.traackr.com	4
http://www.encarolina.com	3
http://localhost	2
http://www.newsblur.com	2
http://tweetedtimes.com	2
http://ebulletin.collected.info	2
http://electrosmart.com	1
http://131.253.14.250	1
http://www.crowdlens.com	1
https://si0.twimg.com	1
http://www.diffbot.com&_=1356882911973 HTTP	1
http://www.diffbot.com&_=1356882926510 HTTP	1
http://www.diffbot.com&_=1356882943166 HTTP	1

Quantifying The Mobile Difference

by guypod on Jun 26, 2012

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