Jim Gettys has been demonstrating the seriousness of the “buffer bloat” problem; see Home Router Puzzle Piece Two — Fun with wireless, and The criminal mastermind: bufferbloat! This is mostly just to draw your attention to Jim’s work, because you can probably improve your own Internet experience by acting on his advice; but I have a related gripe of my own.
As Jim points out, old guys like he and I can remember a time when the Internet used slower connections but felt faster. The good news is that it can probably feel faster again, if certain ISPs and network-hardware engineers stop the bufferbloat abuse.
There’s another overly-fat-pipe symptom that’s been increasingly in my face. I routinely copy big files here and there around the Internet, most commonly from my laptop to tbray.org. There are lots of ways to do this, but I mostly the good old-fashioned scp utility; one of the nice things about scp is that it gives you a real-time readout of how fast the data is flowing and the expected time to completion.
But these days, the readout is often useless. Here’s an example where I’m copying a two-megabyte file, an operation that takes several seconds. What happens is that scp gets its connection set up, and then more or less instantly displays the following big fat lie until the operation completes.
xvr27.pdf 100% 2083KB 694.4KB/s 00:03
No, I am not getting 700KB/sec upstream from my home DSL. What’s happening is that the two megabytes of data drop more or less instantly into some piece of fat but not terribly fast piping and scp thinks they’ve been sent.
If I send something so big that it can’t fit into the pipe, like a movie, the scp display starts out showing some insanely fast data rate until the pipe fills up, then it drops and drops and drops and after several minutes starts approximating the real actual speed of the Internet connection.
I’ve noticed that over the last couple of years the top end of the pipe has gotten fatter and fatter, and the output from scp less and less useful. Grrr.