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Overview of 2.6.34

Most important to end users are the improved Nouveau driver, the improved support of runtime power saving mechanisms in I/O devices, and the faster suspend and resume; important long-term changes include the support of the graphics cores used in Intel's next generation of processors and the currently still rudimentary driver for the Evergreen graphics chips found in Radeon's HD 5000 graphics hardware, which is increasingly used by PC and notebook manufacturers.

Kernel Log Logo Among the most important advancements for corporate Linux users are probably the changes to the virtualisation area, where vhost_net, mactel and the improved SR/IOV support promise more features and flexibility as well as improved data throughput; in the long run, corporate users may also be very interested in the Ceph file system. The Linux kernel's tracing and performance monitoring options, which are continually being improved, are probably most interesting to system admins and developers.

Facts and figures for the latest versions of the Linux kernel

Linux version No. of files1 Rows of source2 (Without documentation) Days No. of commits3 Changes4
2.6.26 24270 9411724
(8535933)
88 9941 8676 files changed
595393 insertions(+)
416143 deletions(-)
2.6.27 24354 9709868
(8690888)
88 10628 15127 files changed
1131171 insertions(+)
912939 deletions(-)
2.6.28 25255 10195507
(9128690)
76 9048 11090 files changed
975689 insertions(+)
490047 deletions(-)
2.6.29 26668 11010647
(9871260)
89 11718 10933 files changed
1347290 insertions(+)
532055 deletions(-)
2.6.30 27879 11637173
(10419567)
78 11989 10259 files changed
1086737 insertions(+)
460298 deletions(-)
2.6.31 29111 12046317
(10778469)
92 10883 8938 files changed
914135 insertions(+)
504980 deletions(-)
2.6.32 30485 12606910
(11242136)
84 10998 10315 files changed
1092987 insertions(+)
530428 deletions(-)
2.6.33 31565 12990041
(11564768)
83 10871 9673 files changed
859458 insertions(+)
479452 deletions(-)
2.6.34 32297 13320934
(11861616)
82 9443 11154 files changed
609584 insertions(+)
278958 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 2.6.35

The release of 2.6.34 marks the beginning of the next merge window, during which the kernel developers incorporate the majority of changes for the next kernel version into the main development branch of Linux. In the past few years, this first phase in the development cycle always lasted almost exactly two weeks. With 2.6.34, however, Torvalds closed the merge window after only ten days and made it clear that he intends to keep the window flexible in future – this is to encourage subsystem maintainers to avoid submitting their changes at the last minute and give more flexibility to Torvalds, who may not have enough time to inspect and merge all the changes submitted during the merge window otherwise.

Linux kernel development cycle

Thanks to the open development process and a long perusal of the tea leaves, The H and the Linux Weather Forecast maintained by the Linux Foundation are already in a position to talk about some of the new features likely to be part of the next kernel increment when a new kernel version is released.

Among the changes the kernel hackers have prepared for integration are further modifications to the Radeon DRM code to improve the utilisation of the power saving techniques offered by modern Radeon graphics chips. Arnd Bergmann and various other developers have also prepared numerous patches to further reduce the use of the Big Kernel Lock (BKL) because it has a negative impact on performance and scalability, and to clearly mark the areas that do still require the BKL. Background details and references to LKML discussions about the changes can be found in the article "Might 2.6.35 be BKL-free?" on LWN.net.

V4L/DVB maintainer Mauro Carvalho Chehab has prepared major modifications to the code which supports infrared remote controls in order to provide a basis for decent IR hardware support in the kernel – this topic, which has occasionally been discussed on the LKML over the past few years, was also the subject of an article which closely examines the related problems and potential solutions and was released on LWN.net a few months ago. Further planned kernel additions are decent support of AMD's Turbo Core and the ath9k_htc driver for the AR9271 Wi-Fi chipset by Atheros.

The developers of a relatively big extension to the kernel debugger are likely to resubmit their code for integration (1, 2, LWN.Net article); Torvalds didn't include the extension in 2.6.34 because he wanted to inspect the code more closely beforehand. Another integration attempt will probably also be made by the developer of Fanotify, who has been working for months to get his solution integrated. Fanotify is interesting for technologies such as on-access virus scanners.

The coming days will show which of these changes will actually be incorporated into the main development branch by Torvalds. The Kernel Log in The H Open will, as usual, report on these and other important developments in the Linux kernel field – including new versions of the stable kernel series (2.6.34.y), which should, over the next few weeks, fix the odd bug or two that was overlooked or ignored during the development of 2.6.34.

In addition, a "Coming in 2.6.35" mini series of the Kernel Log at The H will, as usual, provide a comprehensive discussion of the new additions to the next kernel version. Torvalds will probably release Linux 2.6.35 in early or mid August, provided he and the kernel hackers stick to their usual pace despite the summer and holiday season in the northern hemisphere; the most important changes in this version will then be summarised in a further Kernel Log similar to this one.

Older Kernel Logs can be found in the archives or by using the search function at The H Open Source. New editions of Kernel Logs are also mentioned on Identi.ca and Twitter via "@kernellog2". The Kernel Log author also posts updates about various topics on Identi.ca and Twitter via "@kernellogauthor".

(crve)

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