Faster Web vs. TCP Slow-Start

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9 points·igrigorik··4 comments

This is a very interesting article, as I'd heard references to SPDY before, but didn't know what it was.

However, I am bothered by the fact that this is a piece on performance yet it contains no hard data. Without quantifying the scale of the improvement, I have no idea if this is a 2% optimization, or a 15% one.

Also, does it matter if only one side of a connection has slow start enabled? IE, does it require symmetrical SPDY, or would I see improvements on my server and desktop if I made this change?

(Side note: the requirement for performance data is analogous to ROI data in business.)

For good data and research on this topic, check the work done by the SPDY team (I linked it in the article, but its easy to miss):

http://docs.google.com/a/chromium.org/viewer?a=v&pid=sit...

http://www.chromium.org/spdy/An_Argument_For_Changing_TCP_Sl...

As for slow-start question: CWND is set on the server (on the sender side). You can increase your advertised window, but that will have no effect since it's the server that ramps up the bandwidth, not the client.

If you do control both the server and the client then you will definitely see a difference.

I did miss that link in the article, thanks for the reply and answer.

For more info, checkout this blog post (not me): http://blog.benstrong.com/2010/11/google-and-microsoft-cheat...

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