Github doesn't scale at all for large projects. The kernel is averaging over 8 changes an hour, 24 hours a day. That rate of change can never be handled by doing pull requests and web site review. It only can work with email and review and scriptable processes.
That's roughly one every other hour, so still not quite on the same level. And we do use tooling _in addition_ to GitHub, but reviews are done in PR and not over email.
(FWIW I personally wish more projects worked like the kernel's, but such is life)
Eh, I mildly disagree on web site review. Perhaps not GitHub's pull request/review model, but big projects like Android and Chromium do all their review on web interfaces.
Using Gerrit, which is an automated mimick of Linus' development model.
By the way, we've been succesfully using Gerrit on smaller-scale projects as well (around 8 change-requests / day) and don't even want to think about going back to pull-requests.
What you've said is essentially correct, but I'd like to make a minor correction: Chromium uses rietveld whereas Android (and some Chromium related projects) use gerrit. Rietveld and gerrit have similar workflows except that gerrit is more integrated with git (I think). Both are named after Gerrit Rietveld, a famous Dutch designer.
Just because one big project relies on emails does not mean they scale better. They work for the kernel because with that strong organization pretty much anything could work for the kernel.
Criticisms in the interview were essentially about low discipline that Github interface allows, and how they were not willing to adapt to the kernel needs, not about fundamental deficiencies of pull request based model.
So far nothing has been said about why pull requests via a website might handle less load than pull requests over email.
Greg didn't reply but I think the answer is a resounding yes. I wrote this up a bit back when the devs were using BitKeeper. Lemme go find that. OK, ignore the "I want the 1995 era web pages" look and peek at this:
Github doesn't scale at all for large projects. The kernel is averaging over 8 changes an hour, 24 hours a day. That rate of change can never be handled by doing pull requests and web site review. It only can work with email and review and scriptable processes.