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Summary of 2.6.32

The support of KMS and 3D for recent Radeon graphics cards is likely to be among the new kernel version's most important changes. 3D support especially has been eagerly awaited by quite a few people after AMD stepped up its cooperation with the developers of open source graphics drivers again in summer 2007. However there is one sour note: AMD recently introduced the first Radeon series 5000 graphics cards, which are currently only supported by the generic VESA open source driver.

The improved Radeon support is by no means the only major advancement of 2.6.32. Other highlights include devtmpfs, the optimisation of the scheduler, the simple configuration of test kernels, VGA arbitration, and KSM as well as Timechart support. As in every new version of the kernel, there are also numerous new and improved drivers – designed to make tomorrow's distributions run more smoothly on an even greater number of systems.

Also important are various improvements to the support of the power saving mechanism offered by modern hardware. While each of them individually only tends to add minor, barely measurable advantages, they do make a significant difference on many systems when combined with previous measures and are likely to contribute even more when further planned changes are introduced. Incidentally, the same applies to the changes in every new kernel version of the main development line in general, where some of the new features initially seem inconspicuous or negligible but gain importance in the long run. A good example is KVM virtualisation: Since its inclusion in the Linux kernel, the technology has been improved a little with every new version, and has now reached a level of sophistication that has prompted Linux heavyweight Red Hat to shift the focus away from Xen, which was all the rage in the field of virtualisation a few years ago.

Facts and figures about the latest versions of the Linux kernel

Linux version No. of files1 Rows of source2 (Without documentation) Development Time in days No. of commits3 Changes4
2.6.26 24270 9411724
88 9941 8676 files changed
595393 insertions(+)
416143 deletions(-)
2.6.27 24354 9709868
88 10628 15127 files changed
1131171 insertions(+)
912939 deletions(-)
2.6.28 25255 10195507
76 9048 11090 files changed
975689 insertions(+)
490047 deletions(-)
2.6.29 26668 11010647
89 11718 10933 files changed
1347290 insertions(+)
532055 deletions(-)
2.6.30 27879 11637173
78 11989 10259 files changed
1086737 insertions(+)
460298 deletions(-)
2.6.31 29111 12046317
92 10883 8938 files changed
914135 insertions(+)
504980 deletions(-)
2.6.32 30485 12606910
84 10998 10315 files changed
1092987 insertions(+)
530428 deletions(-)
¹ find . -type f -not -regex '\./\.git/.*' | wc -l
² find . -type f -not -regex '\./\.git.*' | xargs cat | wc -l (find . -name *.[hcS] -not -regex '\./\.git.*' | xargs cat | wc -l)
³ git-log --no-merges --pretty=oneline v2.6.(x-1)..v2.6.(x) | wc -l
⁴ git diff --shortstat v2.6.(x-1)..v2.6.(x)

Kernel trends: Outlook on 2. 6. 33

The Linux kernel development cycle

The open development process (and a look at the tea leaves) makes it possible for the Kernel Log and the Linux Weather Forecast, a "radar screen" maintained by the Linux Foundation, to make an educated guess about some of the new features in store for the next kernel version.

Immediately after the release of 2.6.32 is when the next merge window begins. It usually lasts 2 weeks and serves for integrating the majority of changes scheduled for the following kernel version into the main development branch. The kernel hackers have already prepared numerous changes, some of which we've already mentioned, for this first phase of the development cycle.

Among the probable contenders for integration is DRBD (Distributed Replicated Block Device). Mainly used in High Availability (HA) environments, this replication solution missed the boat in 2.6.32, but Torvalds has advocated integrating it in 2.6.33 despite all the discussion around it. The developers have also prepared code to support the "trim" ATA command, which is particularly interesting for SSDs, for integration into the next kernel version – as well as numerous KVM improvements (1, 2).

The rt2x00 drivers for Wi-Fi chip-sets by RaLink are to be extended to support recent Wi-Fi chips that have so far been only covered by staging drivers. Several improvements to the support of 3D and KMS in recent Radeon cards are also ready for integration. As in 2.6.32 and its predecessors, Btrfs and the tracing infrastructure are also likely to be further upgraded and improved.

As usual, the Kernel Log in c't and at The H Open will present the most important new features of the next kernel version in a "Coming in 2.6.33" mini series over the next few weeks. At the same time, the regular Kernel Log will summarise other developments in the Linux kernel environment – among them new versions of the stable kernel series (2.6.x.y), which usually correct some error or other that kernel hackers and testers failed to catch when developing 2.6.32.

In keeping with the usual development cycle, Linus Torvalds is expected to release Linux version 2.6.33 in mid to late February. A Kernel Log similar to this one at heise open will again discuss the most important changes incorporated.


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