station-wagons and electrons
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Yahoo! London Pub Night – May 27, 2010 – Wallacespace Station wagons and Electrons
Not stuck in a cloud of volcanic ash
Yahoo! London Pub Night – May 27, 2010 – Wallacespace Station wagons and Electrons
Didn’t get sidetracked on my way here
Yahoo! London Pub Night – May 27, 2010 – Wallacespace Station wagons and Electrons
Didn’t go on an extended vacation
Yahoo! London Pub Night – May 27, 2010 – Wallacespace Station wagons and Electrons
Almost not allowed in
Yahoo! London Pub Night – May 27, 2010 – Wallacespace Station wagons and Electrons
Philip Tellisgeekyahoo@bluesmoonhttp://bluesmoon.info/philip@bluesmoon.info
Yahoo! London Pub Night – May 27, 2010 – Wallacespace Station wagons and Electrons
Station wagons and Electrons
Philip Tellis / philip@bluesmoon.info
Yahoo! London Pub Night – May 27, 2010 – Wallacespace
Yahoo! London Pub Night – May 27, 2010 – Wallacespace Station wagons and Electrons
Never underestimate the bandwidth of a station wagonspeeding down the motorway
– Andrew S Tanenbaum?
Yahoo! London Pub Night – May 27, 2010 – Wallacespace Station wagons and Electrons
Should you fly a 747 or a 737?
A 747 seats 400+ passengersA 737 seats about 150Both take about the same time to fly from FRA to LHRA 747 takes longer to load and unload
The best selling aircraft to date is the 737
This analogy would have been much cooler if the Concorde still flew
Yahoo! London Pub Night – May 27, 2010 – Wallacespace Station wagons and Electrons
Bandwidth and Latency
How much data can you transfer at oncev/s
How quickly can you get your data across
Yahoo! London Pub Night – May 27, 2010 – Wallacespace Station wagons and Electrons
But bandwidth is easy
Yahoo! London Pub Night – May 27, 2010 – Wallacespace Station wagons and Electrons
Shannon’s Theorem
C = B × log2(1 +SN
)
C – Channel capacity in bpsB – Bandwidth in HzS – Signal strengthN – Noise strength – S/N measured in dB
Yahoo! London Pub Night – May 27, 2010 – Wallacespace Station wagons and Electrons
Bandwidth can be bought
Bandwidth has increased steadily over timeNetworks, hard drives, memory, CPU, system bus,everything.Bandwidth can be parallelised
Yahoo! London Pub Night – May 27, 2010 – Wallacespace Station wagons and Electrons
Diminishing returns
The benefits of increased bandwidth diminish as you get fatter
Ref: More bandwidth doesn’t matter (much) – Mike Belshe
Yahoo! London Pub Night – May 27, 2010 – Wallacespace Station wagons and Electrons
How fast is the internet?
YUI Blog measured bandwidth at 1Mbps and latency of 262ms
Ref: Analysing Bandwidth & Latency – YUI Blog
Yahoo! London Pub Night – May 27, 2010 – Wallacespace Station wagons and Electrons
Blink
The average human eye takes 300-400msto blink
Yahoo! London Pub Night – May 27, 2010 – Wallacespace Station wagons and Electrons
How fast is the internet?
Akamai measured average global bandwidth at 1.7Mbps
Ref: State of the Internet – Akamai
Yahoo! London Pub Night – May 27, 2010 – Wallacespace Station wagons and Electrons
ISPs
Yahoo! London Pub Night – May 27, 2010 – Wallacespace Station wagons and Electrons
UK ISPs
Keep in mind that the Internet latency from the UK to the US is 90-100ms
Yahoo! London Pub Night – May 27, 2010 – Wallacespace Station wagons and Electrons
Latency – not so easy to sell
Yahoo! London Pub Night – May 27, 2010 – Wallacespace Station wagons and Electrons
Speed Limits
3× 108 m/s – in vacuum2× 108 m/s – in fibre=⇒ 26.42ms × 2(roundtrip from BOS to LON)
Yahoo! London Pub Night – May 27, 2010 – Wallacespace Station wagons and Electrons
Round-trip
It should take a packet around 53ms to go from Boston toLondon and backIt actually takes around 90ms for a packet to go fromBoston to London and backThis is pretty good as far as approaching theoretical limitsgoes
Ref: It’s the latency, stupid – Stuart Cheshire
Yahoo! London Pub Night – May 27, 2010 – Wallacespace Station wagons and Electrons
Round-trip
It should take a packet around 53ms to go from Boston toLondon and backIt actually takes around 90ms for a packet to go fromBoston to London and backThis is pretty good as far as approaching theoretical limitsgoes
Ref: It’s the latency, stupid – Stuart Cheshire
Yahoo! London Pub Night – May 27, 2010 – Wallacespace Station wagons and Electrons
But then again...
Never underestimate the data-transfer capabilities of aGalaxy class starship travelling at Warp 9.875 andfitted with a computer that sounds like Majel Barett
Yahoo! London Pub Night – May 27, 2010 – Wallacespace Station wagons and Electrons
Latency isn’t sexy
When was the last time you saw a TV commercial mentionlatency?
Yahoo! London Pub Night – May 27, 2010 – Wallacespace Station wagons and Electrons
ISPs
Yahoo! London Pub Night – May 27, 2010 – Wallacespace Station wagons and Electrons
UK ISPs
Keep in mind that the Internet latency from the UK to the US is 90-100ms
Yahoo! London Pub Night – May 27, 2010 – Wallacespace Station wagons and Electrons
Latency v/s Bandwidth
Improving latency tends to improve perceived bandwidthImproving bandwidth utilisation can potentially worsenlatencyLarger/complex packets take more time to assemble
This is the difference between a 737 and a 747
Yahoo! London Pub Night – May 27, 2010 – Wallacespace Station wagons and Electrons
Getting around latency problems
Don’t add latency – It’s bad enough without us adding to itCaching – Bring the data closer to where it’s neededParallelise – Reduce the number of serial roundtripsPredict – Get data before it’s needed
Yahoo! London Pub Night – May 27, 2010 – Wallacespace Station wagons and Electrons
If you can, stuff everything into one callHave a look at search.yahoo.com load up in firebug
Yahoo! London Pub Night – May 27, 2010 – Wallacespace Station wagons and Electrons
Parallelise where possible
Downloading a script blocks page load, so do it in thebackground insteadBrowsers will download 4-8 resources from a host inparallel, take advantage of that
Yahoo! London Pub Night – May 27, 2010 – Wallacespace Station wagons and Electrons
Predict what’s next and fetch it
If you know what the user will do next, pre-fetch itYahoo! Search page pre-loads sprites and Javascript forthe results pageLog analysis can tell you which pages are most popular,and pre-fetch those
Ref: Preload CSS & JS without execution – Stoyan Stefanov
Yahoo! London Pub Night – May 27, 2010 – Wallacespace Station wagons and Electrons
Measure your user’s bandwidth & latency
Javascript code to measure your user’s bandwidth & latencyhttp://bluesmoon.info/perf-tests/bw/bw-test-1.3.ziphttp://github.com/bluesmoon/netperf-js
It’s what we used on the YUIBlog test
Yahoo! London Pub Night – May 27, 2010 – Wallacespace Station wagons and Electrons
Useful tools for performance analysis
YSlow – Firefox/Firebug plugin from Yahoo!PageSpeed – Firefox/Firebug plugin from GooglePageTest – Web page testing toolShowSlow – Automated YSlow runs against your URLFiddler – Web debugging Proxy
Yahoo! London Pub Night – May 27, 2010 – Wallacespace Station wagons and Electrons
Further reading
developer.yahoo.com/performance – Yahoo!code.google.com/speed/page-speed/docs/rules_intro.html– Googleslideshare.net/stoyan/the-business-of-performance –Stoyan Stefanovstevesouders.com/blog/ – Steve Soudersphpied.com – Stoyan Stefanov
Yahoo! London Pub Night – May 27, 2010 – Wallacespace Station wagons and Electrons
Stay tuned...
Coming this summer...to an interweb near you
Yahoo! London Pub Night – May 27, 2010 – Wallacespace Station wagons and Electrons
Stay tuned...
BOOMERANG2010 06 24
STARRING: JAVASCRIPT, APACHE, YAHOOSCRIPT: BLUESMOON, PRODUCTION: TOM CROUCHER, CHOREOGRAPHY: CROCKFORD
http://developer.yahoo.net/blog
Yahoo! London Pub Night – May 27, 2010 – Wallacespace Station wagons and Electrons
Photo credits
flickr.com/photos/sully_aka__wstera2/4538240734/flickr.com/photos/gertcha/4168724489/flickr.com/photos/30720140@N08/4290289036/flickr.com/photos/dharmasphere/253277654/flickr.com/photos/gi/117771718/flickr.com/photos/siennaisalive/4436708323/flickr.com/photos/vlastula/300102949/flickr.com/photos/electrichamster/3160580687/flickr.com/photos/burnblue/308441464/
Yahoo! London Pub Night – May 27, 2010 – Wallacespace Station wagons and Electrons
Contact me
Philip Tellisyahoogeek@bluesmoonhttp://bluesmoon.info/slideshare.net/bluesmoonphilip@bluesmoon.info
Yahoo! London Pub Night – May 27, 2010 – Wallacespace Station wagons and Electrons
Thank you
Yahoo! London Pub Night – May 27, 2010 – Wallacespace Station wagons and Electrons
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