Glyn Moody: So does that mean there might be scope for you to write another tool like Git, but for managing people, not code?
Linus Torvalds: I don't think we will. There might be some tooling, but realistically most of the things I do tend to be about human interaction. So we do have tools to figure out who's in charge. We do have tools to say: hey, we know the problem happens in this area of the code, so who touched that code last, and who's the maintainer of that subsystem, just because there are so many people involved that trying to keep track of them any other way than having some automation just doesn't work. But at the same time most of the work is interaction, and different people work in different ways, so having too much automation is actually painful for people.
We're doing really well. The kind of pain points we had ten years ago just don't exist any more. And that's largely because we used to be this flat hierarchy, and we just fixed our tools, we fixed our work flows. And it's not just me, it's across the whole kernel there's no single person who's in the way of any particular workflow.
I get a fair amount of email, but I don't even get overwhelmed by email. I love reading email on my cellphone when I travel, for example. Even during breaks, I'll read email on my cellphone because 90% of them I can just read for my information that I can archive. I don't need to do anything, I was cc'd because there was some issue going on, I need to be aware of it, but I don't need to do anything about that. So I can do 90% of my work while travelling, even without having a computer. In the evening, when I go back to the hotel room, I'll go through [the other 10%].
Glyn Moody: 16 years ago, you said you were mostly driven by what the outside world was asking for; given the huge interest in mobiles and tablets, what has been their impact on kernel development?
Linus Torvalds: In the tablet space, the biggest issue tends to be power management, largely because they're bigger than phones. They have bigger batteries, but on the other hand people expect them to have longer battery life and they also have bigger displays, which use more battery. So on the kernel side, a tablet from the hardware perspective and a usage perspective is largely the same thing as a phone, and that's something we know how to do, largely because of Android.
The user interface side of a tablet ends up being where the pain points have been – but that's far enough removed from the kernel. On a phone, the browser is not a full browser – they used to have the mobile browsers; on the tablets, people really expect to have a full browser – you have to be able to click that small link thing. So most of the tablet issues have been in the user space. We did have a lot of issues in the kernel over the phones, but tablets kind of we got for free.
Glyn Moody: What about cloud computing: what impact has that had on the kernel?
Linus Torvalds: The biggest impact has been that even on the server side, but especially when it comes to cloud computing, people have become much more aware [of power consumption]. It used to be that all the power work originally happened for embedded people and cellphones, and just in the last three-four years it's the server people have become very power aware. Because they have lots of them together; quite often they have high peak usage. If you look at someone like Amazon, their peak usage is orders of magnitude higher than their regular idle usage. For example, just the selling side of Amazon, late November, December, the one month before Christmas, they do as much business as they do the rest of the year. The point is they have to scale all their hardware infrastructure for the peak usage that most of the rest of the year they only use a tenth of that capacity. So being able to not use power all the time [is important] because it turns out electricity is a big cost of these big server providers.