Kernel Log: Higher and Further, The innovations of Linux 2.6.28

Figures for recent Linux Kernels

Linux version	number of files¹	lines of source code²	development time	number of commits³	diffstat⁴
2.6.20	21280	8102486 (7400843)	66Â days	4768	5825Â filesÂ changed, Â 262475Â insertions(+), Â 136162Â deletions(-)
2.6.21	21614	8246470 (7522286)	80Â days	5016	6568Â filesÂ changed, Â 319232Â insertions(+), Â 175247Â deletions(-)
2.6.22	22411	8499363 (7744727)	74Â days	6526	7620Â filesÂ changed, Â 519591Â insertions(+), Â 266699Â deletions(-)
2.6.23	22530	8566554 (7818168)	93Â days	6662	7203Â filesÂ changed, Â 406268Â insertions(+), Â 339071Â deletions(-)
2.6.24	23062	8859629 (8082358)	107Â days	9836	10209Â filesÂ changed, Â 776107Â insertions(+), Â 483031Â deletions(-)
2.6.25	23810	9232484 (8396250)	83Â days	12243	9738Â filesÂ changed, Â 777371Â insertions(+), Â 404514Â deletions(-)
2.6.26	24270	9411724 (8535933)	88Â days	9941	8676Â filesÂ changed, Â 595393Â insertions(+), Â 416143Â deletions(-)
2.6.27	24354	9709868 (8690888)	88Â days	10628	15127Â filesÂ changed, Â 1131171Â insertions(+), Â 912939Â deletions(-)
2.6.28⁵	8995	10195402 (9128591)	70Â days	8995	11076Â filesÂ changed, Â 975468Â insertions(+), Â 489931Â deletions(-)
¹Â find . -type f -not -regex '\./\.git/.' \| wc -l ²Â find . -type f -not -regex '\./\.git.' \| xargs cat \| wc -l (find . -name .[hcS] -not -regex '\./\.git.' \| xargs cat \| wc -l) ³Â git-log --no-merges --pretty=oneline v2.6.(x-1)..v2.6.(x) \| wc -l ⁴Â ;git diff --shortstat v2.6.(x-1)..v2.6.(x) ⁵Â Status as of 19.12.08 13:00UTC

Summary of 2.6.28, and what's coming with 2.6.29

Linux 2.6.28 includes many innovations that will benefit many a Linux user in the short or long term, although if you don't need one of the new drivers right now, it will mostly likely be the long term. Ext4, for example, may not become really significant until a mainstream distribution uses it as the standard filesystem, and that probably won't happen for a few months. Nor is wireless USB support very important at the moment, because the relevant hardware is still rare, and even more time is likely to go by before everyday desktop systems and routine servers will be able to take advantage of the performance improvements in the memory subsystem. However, the kernel hackers have already made provisions for some future challenges.

Kernel Log Beginner Penguin

Development cycle of the Linux kernel
The open development process (and a deep gaze into the tea leaves) makes it possible for heise online, like the Linux Weather Forecast, a "radar screen" maintained by the Linux Foundation, to make an educated guess about what new features are in store in the next kernel version.

The first ("merge window") phase in the Linux kernel development cycle now begins, immediately following the release of version 2.6.28. This phase, during which Torvalds accepts the comprehensive changes into the main development tree for the next kernel version, customarily lasts for two weeks. Following GEM (graphical environment manager), Intel's developers are going to support kernel-based mode-setting (KMS). The developers of the real-time tree are apparently also going to transfer some of the real-time extensions for Linux back into the main development tree. It appears rather unlikely at the moment that the code will manage to set up a privileged administrative Xen domain (Dom0) in 2.6.29, although this can't be totally excluded.

As usual, the Kernel Log, on heise online UK and in c't, in the coming weeks will be reporting on the main innovations included in the main development line of Linux, and on other developments relating to the Linux kernel. These include new versions of the stable kernel series (2.6.x.y) that will, in the next few weeks, probably correct the occasional error that the kernel hackers and testers overlooked while developing 2.6.28. Torvalds will probably release Linux version 2.6.28 in time for CeBIT in early March, or shortly thereafter. As usual, the changes will be described in a detailed kernel log like this one at heise online UK.

(thl/c't)

Appendix:

Infrastructure changes

Changes to drivers and surrounding subsystems