4 ms·

What? a few bytes removed from the HTTP request and you double the speed..??? There is something I don't understand here. I suspect the improvement comes exclu

What? a few bytes removed from the HTTP request and you double the speed..??? There is something I don't understand here. I suspect the improvement comes exclusively from increasing the limit on the number of connections, by way of now using two sources instead of one, rather than from the removal of a few bytes in the HTTP request. Unless I missed something...

WALoeIII 16y ago
TCP Slow start plays a big role here. The fewer the packets required to carry the request, the faster the complete request can be addressed by the webserver, leading to a faster download. http://en.wikipedia.org/wiki/Slow-start http://en.wikipedia.org/wiki/Slow-start Essentially your client waits for ACKs from the server when it sends its first packets. The greater the RTT the higher the penalty. This is part of why DC -> NJ didn't see much benefit but CA -> NJ saw a nice boost. There was a great talk on this at Velocity Conf 2010: http://en.oreilly.com/velocity2010/public/schedule/detail/11792 http://en.oreilly.com/velocity2010/public/schedule/detail/11... - I have not yet found video, but you can flip through the slides. Checkout this visualization of the slow start and you can see how sending even one fewer green dots over a large distance could considerably change the overall time. http://vimeo.com/14439742 http://vimeo.com/14439742
symkat 16y ago
More or less: yes. It's the combination of both removing those excess bytes. If you transmit 10 static files per page request, and have 256bytes of cookies you're sending 2560 bytes of cookies, or 2KiB per page load. That's on the end user's upload bandwidth too, which is typically dramatically less than their download. The lessening of the connection limit also allows more entities to load at the same time, the combined effect is a good increase in speed. Two tweaks for the price of 1. =)
- asuth 16y ago
  It doesn't quite work like that. TCP works in packets, so 256 bytes of cookies does not necessarily translate into an extra packet sent over the network. So if you have 10 static files per page, you might push a few of them over to an extra packet, but not all of them. It's something worth doing, but it's not the biggest win you can get.
- mattmanser 16y ago
  The piece is called 'cookieless domains'. Not 'using static domains for increased connections'. If the actual speed increase is from something totally unrelated to the piece's conclusion then this is really misleading. The static domain trick has been around donkeys.

WALoeIII 16y ago

TCP Slow start plays a big role here. The fewer the packets required to carry the request, the faster the complete request can be addressed by the webserver, leading to a faster download. http://en.wikipedia.org/wiki/Slow-start http://en.wikipedia.org/wiki/Slow-start Essentially your client waits for ACKs from the server when it sends its first packets. The greater the RTT the higher the penalty. This is part of why DC -> NJ didn't see much benefit but CA -> NJ saw a nice boost. There was a great talk on this at Velocity Conf 2010: http://en.oreilly.com/velocity2010/public/schedule/detail/11792 http://en.oreilly.com/velocity2010/public/schedule/detail/11... - I have not yet found video, but you can flip through the slides. Checkout this visualization of the slow start and you can see how sending even one fewer green dots over a large distance could considerably change the overall time. http://vimeo.com/14439742 http://vimeo.com/14439742

symkat 16y ago

More or less: yes. It's the combination of both removing those excess bytes. If you transmit 10 static files per page request, and have 256bytes of cookies you're sending 2560 bytes of cookies, or 2KiB per page load. That's on the end user's upload bandwidth too, which is typically dramatically less than their download. The lessening of the connection limit also allows more entities to load at the same time, the combined effect is a good increase in speed. Two tweaks for the price of 1. =)

asuth 16y ago
It doesn't quite work like that. TCP works in packets, so 256 bytes of cookies does not necessarily translate into an extra packet sent over the network. So if you have 10 static files per page, you might push a few of them over to an extra packet, but not all of them. It's something worth doing, but it's not the biggest win you can get.
mattmanser 16y ago
The piece is called 'cookieless domains'. Not 'using static domains for increased connections'. If the actual speed increase is from something totally unrelated to the piece's conclusion then this is really misleading. The static domain trick has been around donkeys.