Now that the 3.5 Linux kernel has been released, it's time for the
traditional look at who wrote it. Here we'll try to summarize who did
all of the work that went into this release.
Fastest-changing kernel ever
The 3.5 kernel was released one day faster than the 3.4 kernel was, in
62 days. The last time a kernel was released this quickly was back in
2005 with the 2.6.14 kernel release (61 days).
In those 62 days, the kernel developers crammed in a record-breaking
176.73 changes per day (7.36 changes per hour.) This is the
fastest-changing kernel that has been recorded since I started keeping
track of this development metric back in the 2.5 kernel release series.
These changes resulted in the following overall changes:
|Changes in 3.5|
|571987 ||lines added|
|358836 ||lines removed|
|135848 ||lines modified|
The kernel is still increasing at a pretty constant 1.37%
growth in the number of lines and files, which is similar to the
growth rate of the past three kernel releases.
1,195 different developers contributing patches to
the 3.5 kernel;
those developers worked for at least 194 different companies.
The names of the contributing developers are
pretty familiar to those who track these statistics:
|Most active 3.5 developers|
|H. Hartley Sweeten||135||1.2%|
|David S. Miller||131||1.2%|
|Eric W. Biederman||73||0.7%|
|Arnaldo Carvalho de Melo||71||0.6%|
|Hans de Goede||68||0.6%|
|By changed lines|
|H. Hartley Sweeten||13083||1.7%|
|David S. Miller||7445||1.0%|
In the quantity category (remember, we don't judge quality), I did a
large number of cleanup patches removing old USB logging macros from the
system, which resulted in the majority of my changes in the 3.5 kernel.
Axel contributed a great number of regulator driver fixes and
enhancements, and Mark Brown did the majority of his work in the sound
system-on-a-chip drivers area. H. Hartley Sweeten has been working on
cleaning up the Comedi (data acquisition) drivers to get them ready to
move out of the staging area of the kernel. This work has him showing
up in these statistics for the first time. And rounding out the top
five is David Miller with a large number of networking core and driver
Along with H. Hartley Sweeten, Daniel Vetter is also a newcomer to the "top
changesets" list. His contributions came from numerous
changes and enhancements to the Intel graphics drivers.
Although Hans Verkuil is
also a name that might not be familiar to many, his
contributions to the Video4Linux drivers and core code show he is a
core contributor to a subsystem that many users rely on every day.
Considering the statistics in lines changed, Paul Gortmaker leads by
virtue of the fact that he deleted all of
the old Token Ring drivers from the kernel.
Viresh Kumar did a lot of SPEAr processor and driver work, adding
numerous new drivers for the platform.
Steven Rostedt did a large amount of development on
ftrace and ktest (a kernel-testing tool). H. Hartley
Sweeten did the aforementioned Comedi driver cleanup work, and Dave
Arlie made major changes in the area of graphics drivers.
Reviewing the work
All kernel patches are reviewed and "Signed-off-by" a subsystem
maintainer before they are committed to the Linux kernel.
The developers with the most sign-offs for the 3.5 kernel were as follows:
|Developers with the most signoffs (total 20391)|
|David S. Miller||922||4.5%|
|Mauro Carvalho Chehab||605||3.0%|
|John W. Linville||493||2.4%|
|Arnaldo Carvalho de Melo||165||0.8%|
|Wey-Yi W Guy||146||0.7%|
|H. Hartley Sweeten||135||0.7%|
I ended up doing the most sign-offs for this kernel release because of many
changes in the staging and USB subsystems. David
Miller follows with his work in the networking and networking driver
trees, as well as in the IDE drivers. Mauro is the maintainer of the
Video4Linux subsystem, Mark Brown is the maintainer of the embedded
sound drivers, and John Linville is the maintainer of the wireless
These numbers reflect the picture of what has been happening in the past
few kernel releases, with the majority of changes happening in the
staging and networking areas of the kernel.
Who sponsored this work
Here is the list of the companies who sponsored the developers doing the
work for this kernel release, and the number of changes attributed to
|Top changeset contributors by employer|
|Vision Engraving Systems||135||1.2%|
Longtime readers of this series of articles will notice that Linaro has
appeared in the top 5 kernel developer companies by number of
contributions for the first time. This is due to the increased
number of patches Linaro has been contributing, as well as the
organization's wish to have the member company employees' contributions
be counted as coming from Linaro, instead of the member company itself,
as we had previously been doing.
A newcomer to the top 20 companies is Vision Engraving Systems, thanks
to the Comedi development work from H. Hartley Sweeten.
With his work, hopefully this subsystem can move out of the staging area of the
kernel in a future release.
Other than the large jump from Linaro, the other companies in the top 25
are well known. Even NVIDIA—despite Linus's well-publicized, and in my
opinion well-deserved, criticism
of its Linux graphics driver
development efforts—continues to be a large contributor to the kernel
in the area of embedded processor support for its products. Texas
Instruments, Samsung, MiTAC, Wolfson Microelectronics, Qualcomm, Renesas,
and Nokia are also primarily focused in the embedded Linux area, showing
the wide range of ongoing company support for Linux in embedded systems.
Work continues as usual
With the 3.5 kernel release, the number of contributors remains as
high as previous releases, the rate of contributions is greater than
ever (as measured by number of patches per day), and the rate of increase
in the size of the kernel code remains the same as it has been for the past
This shows that the kernel development community is still growing, and
maintaining its incredibly rapid development cycle, ensuring that
Linux remains the largest software engineering project ever.
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