Linux 3.3: Finally a little good news for bufferbloat

I, Cringely » Blog Archive » Linux 3.3: Finally a little good news for bufferbloat – Cringely on technology.

Bufferbloat, as you’ll recall from my 2011 predictions column, is the result of our misguided attempt to protect streaming applications (now 80 percent of Internet packets) by putting large memory buffers in modems, routers, network cards, and applications. These cascading buffers interfere with each other and with the flow control built into TCP from the very beginning, ultimately breaking that flow control, making things far worse than they’d be if all those buffers simply didn’t exist.

Bufferbloat was named by Jim Gettys of Bell Labs, who has become our chief defender against the scourge, attempting to coordinate what’s become a global response to the problem.

What AQM does is monitor the buffer, and signal the end points to slow down any time the buffer starts to fill, either due to that one transfer or competing transfers, by dropping or marking packets.  So the buffer is kept (almost) empty, except when it is handling a burst of traffic. So the steady state latency of the buffer, rather than being the size of the buffer, is set by the size of the bursts in traffic.  The size of the buffer becomes almost irrelevant.