The Dirk and Linus show comes to Seoul

One of the recurring features of Linux Foundation events is an on-stage discussion between Dirk Hohndel and Linus Torvalds on a variety of kernel-related topics. The Korea Linux Forum in Seoul, South Korea did not diverge from this pattern. The pair talked about a wide range of topics; there were few surprises and little that will be controversial, but the discussion did include some insights into how the community is doing and where the kernel is going.

Dirk started by asking about the status of the upcoming 4.3 kernel; Linus responded that this has been the most pleasant development cycle in quite a while. He was pleased that we managed to remove an entire filesystem implementation this time around. Kernel development cycles have been going smoothly in general, but 4.3 has been extraordinary in that respect.

There are, Linus said, no big revolutionary changes in the 4.3 kernel. As is usually the case in recent years, the community's work is mostly about refining the code and adding lots of new drivers. That is why things are going so smoothly in general — there is simply "nothing special" going on.

What about the new code name for 4.3 (which happens to be "Blurry Fish Butt")? The kernel's code name, Linus said, has no real meaning, it's just a sort of internal joke that will never appear in kernel documentation or in kernel messages. Every now and then Linus will see a news item about something like suicidal squirrels, and it becomes the new kernel code name. The current name is a reference to Linus's underwater photography skills which, by his own word, are somewhat lacking.

Dirk noted that kernel development proceeds at an insane and still increasing pace; are the infrastructure and the people able to keep up with it all? Linus responded that, while a lot of patches are merged in any given development cycle, individual patches do not necessarily get in quickly. For some work, it can take years to get a change ready for merging into the mainline. The simple changes should go in quickly, but complicated infrastructural changes can take a long time. So it's not that things are going quickly; there are just a lot of developers with a high combined throughput. Latencies can be long for specific patches, and there are some who say that they should be even longer.

Is there anybody out there who understands the entire kernel? Linus said that nobody does. There are some people who have a good overview of the whole kernel, and Linus, at least, generally knows who to blame for any specific problem. But with a project the size of the kernel it's not possible for anybody to have a deep understanding of the whole thing. The good news is that we don't need anybody to have such an understanding; the deep understanding of the whole kernel exists, it's just distributed over a large number of developers.

How about participation from Asia in the kernel development community? According to Linus, "is there enough participation?" might not be the right question to ask. Yes, there is a lot of participation from Asia; it is much higher than it was ten or even five years ago. But there could always be more. There are language and cultural barriers that, unfortunately, will always make it easier for developers from Europe and North America to participate. That said, things seem to be working fairly well.

With regard to how an aspiring kernel developer should start, Linus has always said the same thing: he can't tell developers what to do. It is important, instead, that developers work on things they want to do. Those developers are the ones that will stick around for years, and developers who stay around are worth far more than those who show up to send in one random new feature. Nobody can tell such developers what they should be working on, though, Linus acknowledged, employers tend to do just that. Hopefully people in that situation will find that they like what they are being directed to do. The most valuable and useful developers are the ones who find their own passion.

Along those lines, Dirk asked: "what motivates you?" What keeps Linus working on the kernel? The answer was that he would get bored otherwise; he hates television and can only spend so much time diving. He likes kernel development because it's interesting, even though he doesn't really write code anymore. Most of his time is spent reading email now; he finds the discussions interesting and thinks that his is a worthwhile job. He never really thought of himself as a people person, but it turns out that he likes it. Dirk asked when Linus might stop, to which he responded that the community should simply kick him out when he starts drooling and his brain doesn't work more.

Any regrets after 24 years of kernel work? We have, Linus said, done quite well, so any discussion of regrets is "crazy talk." There is no point in second-guessing himself. The only big decision that really mattered was whether to give the code away or not, and he got that one right. Anything else can be fixed over time.

How many kernel compiles has he done? It used to take about twelve minutes to compile a kernel; over time, the kernel has gotten bigger, but the hardware has gotten faster; the current time is about 22 minutes for an allmodconfig kernel. He does about ten builds per day during the merge window, a couple otherwise. Kernel development has been happening for about 8800 days; the bottom line, Linus guessed, was about 100,000 compiles.

With regard to which non-kernel projects Linus finds interesting, he said he doesn't really track outside projects. He does track the activities of a few people, but, since he uses Google+ for this purpose, the number of people he tracks is necessarily quite small. It is interesting, he said, to see what other hobbies kernel developers have. With regard to distribution projects, he doesn't like telling people which distributions he uses because he doesn't want to give anything like an official stamp of approval to any of them; his distribution choice also tends to vary over time.

What about the Git project — what made that project successful? Linus gave a lot of credit to BitKeeper which, despite its licensing issues, changed how the kernel community did development. Git, of course, is an improvement on BitKeeper, but BitKeeper showed the benefits of distributed development when nobody else was working in that area.

Once Git was around, its use by the kernel community helped it to spread quickly. Its immutable object model turned out to make it easy for service providers to use, enabling companies like GitHub. Ten years ago, developers were resistant to thinking about source-code management issues; Git forced them to look at it and to realize how much better distributed source-code management is. Git was not the first in this area, but it was the one that created wide awareness of a better way of doing things.

Even so, Linus was a bit surprised at how quickly Git took off. When he developed Git, CVS had been around "forever," and he thought it would continue to stick around for a long time. But something happened, and some high-profile projects migrated over to Git. Before long, things flipped around, and Git is now the most common source-code management system out there. Linus said that he is proud to have created two separate projects that have changed the world.

That said, he's not looking for another project to take on; indeed, he never was. Even with Git, he hated the fact that he had to start working on it; it was a sign of pain in his life. He would rather not run into more major pain points in the future.

Dirk suggested that Linus is approaching an age where a mid-life crisis is due. He already has a fast car and an expensive hobby; what is his plan for a crisis? Linus replied that he's a bit ahead of the curve, having gotten his fast car many years ago. His mid-life crisis happened at 30.

Many famous people, Dirk said, have used their fame to advance a larger cause. Why is it that we don't associate Linus Torvalds with a bigger cause? Linus answered by claiming to just not be a very caring person; he does what he does because it is interesting to him, and not because he is looking to change the world. His goal is to make the best operating system there is; he does technology because it's interesting. Perhaps that will be the form of his real mid-life crisis: when a desire to create a legacy strikes him.

That said, he does have ideals; he supports the Electronic Frontier Foundation, for example. But he is not a huge Free Software Foundation fan; they simply push their agenda too strongly. Perhaps he should be using his influence to push topics that he cares about, but he really thinks that his time is best spent on boring technical stuff.

The final question was: where will Linux be in 24 years? Linus replied that he doesn't really even know where things will be in one year. He can say that the 4.3 release will happen in a week, and his vision goes a bit further than that. He generally plans one or two releases into the future, but he can't force any of his plans to happen, so any kind of detailed planning would be worthless. Instead, developers and companies each have their own visions, and they are pushing things in the direction they want them to go. The strongest of those visions will survive; it is, he said, a sort of biological warfare on a software scale. The end result has served us well for 24 years, and should continue to do so for some time yet.

[Your editor would like to thank the Linux Foundation for supporting his travel to the Korea Linux Forum].

Index entries for this article
Conference	Korea Linux Forum/2015

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