Download/Upload Buffer Purpose

[mepherion]

What does the download and upload buffer setting do? When would you need to change it from the default values?

[tnodir]

Most of the code for speed limiting was taken from the win-shaper.

Please see its blog post:

By default it ships with the same connection profiles as WebPageTest but you can also specify custom profiles including how big the network buffers should be (150KB roughly mirrors the dummynet default of 100 packets though in practice buffers on real networks can be even larger).