Quantifying The Mobile Difference

The Mobile Difference – In Numbers

Guy Podjarny
@guypod
http://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

Apple Laptop vs. Mobile, CPU/RAM


Fast Mobile Browsing is all the rage


Better CPU matters in Benchmarks

Quad Core, ~1.5 Ghz

Dual Core, ~1 Ghz

http://www.anandtech.com/show/5810/samsung-galaxy-s-iii-performance-preview
Faster Forward
TM
©2012 Akamai

Perf of iOS5 across different hardware

Sunspider'JS'Benchmark,'iOS'5'Devices'

10x
24yr'old'MBP,'2x2.7'Ghz' 230'
Better

iPhone'4S,'2x800'Mhz' 2250' 37%
Better
iPhone'4,'800'Mhz' 3545' 25%
Better
iPhone'3GS,'600Mhz' 4737'

0" 500" 1000" 1500" 2000" 2500" 3000" 3500" 4000" 4500" 5000"


Test Time!


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


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%

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


Cellular Network
!=
Broadband Network

Akamai Confidential

Claim: Cellular Networks are SSSLLLOOOOWWWW

Low
Bandwidth

High Latency

High Packet
Loss

Volatility


Bandwidth

http://www.flickr.com/photos/pasukaru76/4228438307/
Faster Forward
TM
©2012 Akamai

Cellular Network Speed – Wikipedia
Protocol Max Downlink Max Uplink
GPRS 56-115 Kbps
CDMA200 (1X) 153.6 Kbps
Edge 236.8 Kbps
3G Bar 2 Mbps stationary client
384 Kbps moving client
EV-DO 2.5-4.9 Mbps 0.15-1.8 Mbps
EDGE Evolution 1.6 Mbps 0.5 Mbps
HSDPA 2 Mbps 200 Kbps
HSPA+ 14.4 Mbps
4G Bar 1 Gbps stationary client
100 Mbps moving client
HSPA+ Release 11 21-672 Mbps 5.8-168 Mbps
LTE 100-300 Mbps 50-75 Mbps
WiMax 37-365 Mbps 17-376 Mbps

You only get those speeds it if you’re this guy…

http://www.flickr.com/photos/23081877@N02/2798378080/
Faster Forward
TM
©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, 2012

Source (PCWorld): http://bit.ly/JX7MQw Faster ForwardTM ©2012 Akamai

Mobile Network Speed, Akamai SOTI, Q4 2011

http://www.akamai.com/stateoftheinternet/

Average Broadband Speeds

http://www.netindex.com/download/
http://www.akamai.com/stateoftheinternet/ 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


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 ForwardTM
http://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

Cisco Cloud Index, 2010-2015
“Global average fixed latency is 125 and average mobile
latency is 290… Global mobile consumer average latency is
307.3 ms”


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)"


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


Test Time!

•  Question:
How much impact does the difference in Bandwidth & Latency
have on web performance?

•  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


Download BW Impact on Load Time

Poor Cell Conn

DSL
Cable FIBER

Avg Cell Conn


Upload BW Impact on Load Time

Poor Cell Conn Avg Cell Conn

DSL
Cable FIBER


Latency Impact on Load Time
Poor Cell Conn

Avg Cell Conn
DSL
Cable
FIBER


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


Packet Loss


Packet Loss – Broadband vs Mobile
Average Packet Loss

Mobile 0.6%

Broadband
0.017%


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 small
http://pam2012.ftw.at/papers/PAM2012paper6.pdf


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%

Apple Network Link Conditioner

780/330 Kbps
200ms RTT

850/420 Kbps
190ms RTT 780/330 Kbps
200ms RTT
1% Packet Loss


Network Link Conditioner in iOS 6? (via @jedisct1)


Volatility


Different protocols lead to different speeds

http://www.ericsson.com/res/docs/2012/traffic_and_market_report_june_2012.pdf
Faster Forward
TM
©2012 Akamai

Signal Strength affects download speed


Different Carriers have different average speeds

Source (PCWorld): http://bit.ly/JX7MQw Source: Ofcom


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


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%

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


HTTP Pipelining


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?

•  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


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"

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…


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…


Thank You!
Questions?

The Mobile Difference – In Numbers

Guy Podjarny
@guypod
http://www.guypo.com/ Akamai Confidential

Quantifying The Mobile Difference

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