Algorithms to Live By: The Computer Science of Human Decisions

by Brian Christian

Yet it’s precisely such “packet drops” that lead a computer to notice that one of its packets hasn’t been acknowledged, prompting AIMD to start halving the bandwidth. Dropped packets are the Internet’s primary feedback mechanism. A buffer that’s too large—a restaurant taking every order no matter how short-staffed the kitchen, a modem taking every packet that comes in regardless of how long it’ll take to send them on—prevents this moderation from happening as it should. Fundamentally, buffers use delay—known in networking as “latency”—in order to maximize throughput. That is, they cause packets (or customers) to wait, to take advantage of later periods when things are slow. But a buffer that’s operating permanently full gives you the worst of both worlds: all the latency and none of the give.