The Linux Foundation has just published
, written by Greg Kroah-Hartman, Amanda McPherson, and your
editor, reviewing the origins of the code merged into the kernel from
2.6.11 through 2.6.24. As LWN readers know, the 2.6.25
getting close to release. So this seems like as good a time as any to look
at what happened with the process in this release cycle.
As of this writing, 12,269 individual changesets have been merged for
2.6.25 - a new record. That beats the previous record (2.6.24, with a mere
10,353 changesets) by almost 2,000. There were 1,174 individual developers
involved with 2.6.25, 419 of whom contributed one single patch. All told,
those developers worked for 159 employers (that your editor could
identify). The changes added 766,979 lines of code and removed 399,791, for
a total growth of 367,188 lines.
Here is an updated version of a plot that your editor has been fond of
showing during talks in recent years:
This plot shows a cumulative count of lines changed over time, with kernel
release dates added in. The effects of the merge window policy can be seen
in the stair-step appearance of the plot. The steps appear to be getting
bigger, but the time between releases has also increased slightly, so the
overall rate of change remains roughly constant. It is a high rate, with
over five million lines changed - well over half the total - in the last
So who did this work? Here is the traditional table of the most active
developers in the 2.6.25 series:
|Most active 2.6.25 developers|
|Mauro Carvalho Chehab||136||1.1%|
|David S. Miller||112||0.9%|
|By changed lines|
|Mauro Carvalho Chehab||9332||1.0%|
There are some familiar names on this list, but also some new ones.
Bartlomiej Zolnierkiewicz contributed more changesets than any other
developer; his work is contained entirely within the IDE subsystem.
Patrick McHardy works in the networking area, mostly (but not exclusively)
with the netfilter subsystem. Adrian Bunk continues to make small fixes
all over the tree and to relentlessly hunt down unused code for removal.
Ingo Molnar remains busy in his new role as one of the x86 maintainers;
scheduler work also accounts for a number of his changes. Paul Mundt
maintains the SuperH architecture.
The picture is a little different when one considers how many lines of code
were changed. Jesper Nillson's work was done within the CRIS
architecture. David Howells works all over the tree; his largest
contribution was the addition of the MN10300 architecture code. Eliezer
Tamir contributed the bnx2x (Broadcom Everest) network driver, and Kumar
Gala works with the PowerPC architecture.
There is relatively little change in the lists of employers associated with
all of this work (please remember that the numbers associated with
employers are necessarily approximate):
|Most active 2.6.25 employers|
|By lines changed|
As usual, one can also look at who applies a Signed-off-by header to code
for which they are not the author. These headers illustrate the chain of
trust which gets code into the kernel. For 2.6.25, the top approvers of
|Sign-offs in the 2.6.25 kernel|
|David S. Miller||1444||11.7%|
|John W. Linville||614||5.0%|
|Mauro Carvalho Chehab||447||3.6%|
Some of these developers are quite busy; Andrew Morton is signing off
more than twenty patches every day - weekends included. The gatekeepers to
the kernel continue to work for a relatively small number of companies,
with the top ten employers accounting for over 75% of all non-author
All told, all these numbers paint a picture of a development process which
is healthy and continues to set a fast pace. It incorporates work from an
increasingly large community of developers who are able to work in a highly
cooperative manner despite the fact that their employers are fierce
competitors. There are very few projects like it.
(Thanks to Greg Kroah-Hartman for his help in the creation of these
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