[Bloat] I feel an urge to update this

Mikael Abrahamsson swmike at swm.pp.se
Thu Sep 25 01:32:21 EDT 2014


On Wed, 24 Sep 2014, David Lang wrote:

> The problem is that you don't know what the connectivity is going to be. 
> (unless you are connecting to the same IP as an existing connection). 
> Your first few hops are fairly predictable, but after that you have no 
> idea if you are going to be connecting to a server on a low bandwidth 
> link, one behind a very congested router, or one with better 
> connectivity than you have.

I am not saying that we *know*, but we might have a pretty good idea. 
Better than to do the same thing regardless of circumstances. If I know my 
home connection is 250/50 megabit/s, then there is no reason to treat it 
like a 0.1 megabit/s connection or a 10GE connection.

> using fq_codel on every bottleneck link will make TCP work pretty well 
> across that entire range of connectivity

Well, that'll fix one thing, but for instance the IW4 and IW10 debate. I'm 
sure IW10 works *great* on a 100/100 megabit/s connection when the server 
is 10GE connected, but it's less than optimal for a 0.1 megabit/s 
connection.

So why can't the client hint the server that, hmm, I seem to be on a 
fairly slow connection here, don't send me too much at once? Or it can 
hint that hey, it seems most times I get pretty large TCP window sizes, so 
it's ok to start with IW10?

-- 
Mikael Abrahamsson    email: swmike at swm.pp.se



More information about the Bloat mailing list