Steam’s lousy throttling

Steam does a lousy job of bandwidth throttling. I had it set to limit downloads to 512kbytes/sec. (Why? Because despite using a fancy router with QoS control, QoS still sucks in 2014. Can’t stream video while downloading, derp). Here’s the graph of throughput from my router. X axis scale is 1 pixel = 2 seconds, max throughput is about 900 kbytes/sec. I turned off throttling halfway through.

Screen Shot 2014-03-02 at 8.35.12 AM


So looking at the first half of that graph, what Steam is actually doing is running at full capacity for about 10 seconds, then backing off to the requested 512 kbytes/sec for about 10 seconds, then averaging it out by going slow for 10 seconds. Back and forth. That’s just awesome.

I sure wish QoS worked on the modern Internet. The academic research I’m familiar with was all worried about solving the hard problem of fair congestion management through the whole Internet. I don’t care about that; I just want to manage QoS on one link, from my router to my ISP over the slow pipe.