linux kernel development process by Greg Kroah-Hartman

by iman

last week Greg Kroah-Hartman had some talk in google company about linux kernel development process .

here is video of his talk;he’s not talking about technical stuffs so i highly recommend you watch at it (if you’r interested in kernel); and if you don’t have high bandwidth so take a look at his slides .

anyway, took some notes which might be interesting for you, too.

fastest software project known to any body …

yes , he’s actually right.linux has the best support of processors in the history of computing (don’t know exactly how many architectures it supports, but as far as i know it’s around more than 25 architectures), even supports devices more than any os ever has .

ohh common buddy, if you r thinking about winmodems so you are completely wrong. it has long story why linux don’t support such simple devices well and talking about it’s reasons takes a long time(maybe i’m going to talk about this another time)

so let me give some examples how fast development of linux is :

4,300 lines added and 1,800 lines removed and 1,500 lines modified per day in 2007-2008 ; which means there are 3.69 changes per hour :0 . all these changes led to new release of kernel every 11 weeks (about two and half month).

and today linux has about 9.2 million lines of codes which ten percent increasing per year.

BTW : i should mention that this is all codes of all drivers, architectures and what ever you think . but your kernel’s distribution with specific architecture doesn’t have that much code.

and then he talked about new version numbering of releases (it’s 4 years old. new ?! 😀 ) …

he talked about how people and their codes are managed:

as you see in the picture developers submit their codes to driver/file maintainers so they submit new changes to subsystem maintainers (subsystem maintainers are like usb, pci, vfs, security and core …) ; finally codes are submitted to andrew morton and linus torvalds. (the final stable code is in linus’s tree) .

maybe you’r curious about “-next” ???

this is new story (2008/06/10). i haven’t worked on it, a lot . you can find more about it here .

then he talked about peoples …

2,399 unique developers are working on kernel right now . from 2.5 to 2.6 only top 20 people did 80 percent of kernel developing; but now top 30 people do just 30 percent .

top ten developers by quantity (by quantity here means number of changes not quality of their codes nor effectiveness or even importance of their changes, just quantity )

are : {<name >, <number of changes>}

  1. Adrian Bunk, 754
  2. Al Viro , 698
  3. Thomas Gleixner, 656
  4. David S. Miller , 655
  5. Bart Zolnierkiewicz, 637
  6. Paul Mundt , 610
  7. Ralf Baechle, 604
  8. Ingo Molnar , 596
  9. Patrick McHardy, 554
  10. Tejun Heo , 530

top signed-off-byhere is top ten signed-off-by of developers .(signed-off-by ? they r people who review and accept others code and submit them to tree.)

there is some interesting note in this list .although all changes are send to linus to be submitted in main tree but andrew is the first one 😀 ; why ?

that’s easy, linus get all changes but as he trust other developers, so he don’t review all of them again.

so who is funding this work ?

who is funding this work ? here is list of top then contributors of linux.

this is so interesting when we see amateurs are the first one in this list 🙂

finally he talked about Google employee contributions and finished it with question/answers .

BTW : Greg has some other interesting article about this topic which was submitted in Linux Symposium 2007 ; you can find it here .