What kernel versions is this available? How do you check if it's enabled?

Are you likely to get it automatically if you run a recent stock Debian / Ubuntu / Alpine / Arch / Mint / whatever? Or do you have to do something specific to enable it?

> it does require driver changes which is a bit of a pain. By my count it is supported by more than fifty drivers

How do you check? Can you give an example of where the code's different in a driver that supports it and a driver that doesn't? It might be nice to have a Python script to analyze the kernel source tree and produce a list of which drivers support BQL, it might affect my purchasing decisions if I'm building a system I expect to have heavy network loads (media server / NAS or the like).

As the article states, BQL has been around since 2011 so it's most likely available - you can grep for CONFIG_BQL in your /boot/config-* file to confirm.

I'm not aware of any up-to-date list of drivers that support BQL. You could try something like [1], but I'm not sure if it will find all relevant drivers.

[1] https://livegrep.com/search/linux?q=file%3A%5C.c%24%20netdev...