KernelNewbies
  • Comments
  • Immutable Page
  • Menu
    • Navigation
    • RecentChanges
    • FindPage
    • Local Site Map
    • Help
    • HelpContents
    • HelpOnMoinWikiSyntax
    • Display
    • Attachments
    • Info
    • Raw Text
    • Print View
    • Edit
    • Load
    • Save
  • Login

Kernel Hacking

  • Frontpage

  • Kernel Hacking

  • Kernel Documentation

  • Kernel Glossary

  • FAQ

  • Found a bug?

  • Kernel Changelog

  • Upstream Merge Guide

Projects

  • KernelJanitors

  • KernelMentors

  • KernelProjects

Community

  • Why a community?

  • Regional Kernelnewbies

  • Personal Pages

  • Upcoming Events

References

  • Mailing Lists

  • Related Sites

  • Programming Links

Wiki

  • Recent Changes

  • Site Editors

  • Side Bar

  • Tips for Editors

  • Hosted by WikiWall

Navigation

  • RecentChanges
  • FindPage
  • HelpContents
Revision 9 as of 2011-05-20 23:59:35
KernelNewbies:
  • Linux_2_6_39

/!\ The changelog is not ready due to lazyness^Wtime constraints. /!\ It will be completed in the next days and, of course, it will be ready again for 2.6.40. Meanwhile, you can check the kernel reports in LWN [https://lwn.net/Articles/433854/ (1], [https://lwn.net/Articles/434637/ 2], [https://lwn.net/Articles/435716/ 3)] or H Open [http://www.h-online.com/open/features/What-s-new-in-Linux-2-6-39-1242910.html (1)]

TableOfContents()

1. Prominent features (the cool stuff)

1.1. Ext4 SMP scalability

In 2.6.37, huge Ext4 scalability improvements were merged and [http://kernelnewbies.org/Linux_2_6_37#head-5b9d7940fa4e8294ceaac86a74beb021b2fce3e3 mentioned in the changelog]. But this feature was not ready for prime time and had been disabled in source before the release - something that the changelog didn't mention. In this release it has been enabled by default. This is the text from the previous changelog:

"In this release Ext4 will use the "bio" layer directly instead of the intermediate "buffer" layer. The "bio" layer (alias for Block I/O: it's the part of the kernel that sends the requests to the IO/O scheduler) was one of the first features merged in the Linux 2.5.1 kernel. The buffer layer has a lot of performance and SMP scalability issues that will get solved with this port. A FFSB benchmark in a 48 core AMD box using a 24 SAS-disk hardware RAID array with 192 simultaneous ffsb threads speeds up by 300% (400% disabling journaling), while reducing CPU usage by a factor of 3-4"

Code: [http://git.kernel.org/linus/6fd7a46781999c32f423025767e43b349b967d57 (commit)]

1.2. IPset

Official IPset webpage: [http://ipset.netfilter.org/ http://ipset.netfilter.org/]

IPset allows the creation of groups of network resources (IPv4/v6 addresses, TCP/UDP port numbers, IP-MAC address pairs, IP-port number pairs, etc), called "IP sets", then you can use those sets to define Netfilter/iptables rules. These sets are much more lookup-efficient than bare iptables rules, but may come with a greater memory footprint. Different storage algorithms (for the data structures in memory) are provided in ipset for the user to select an optimum solution. IPset has been available for some time in the xtables-addons patches and is now being included in the Linux tree.

This tool is useful to do things like: store multiple IP addresses or port numbers and match against the collection by iptables at one swoop; dynamically update iptables rules against IP addresses or ports without performance penalty; express complex IP address and ports based rulesets with one single iptables rule and benefit from the speed of IP sets.

Code: [http://git.kernel.org/linus/a7b4f989a629493bb4ec4a354def784d440b32c4 (commit 1], [http://git.kernel.org/linus/72205fc68bd13109576aa6c4c12c740962d28a6c 2], [http://git.kernel.org/linus/de76021a1bb35e3560afccf741d1119a872aea49 3], [http://git.kernel.org/linus/6c027889696a7a694b0e2f6e3cabadefec7553b6 4], [http://git.kernel.org/linus/543261907dc3c4e90845acfcd602ebdbfdfcb4f0 5], [http://git.kernel.org/linus/07896ed37b94599a1b8ea97f4bd5766be71390f4 6], [http://git.kernel.org/linus/5663bc30e6114b6ba88cc428619ede46a3246a7b 7], [http://git.kernel.org/linus/41d22f7b2e48c77175b62cec3797d7d7173a626e 8], [http://git.kernel.org/linus/b38370299eeaba4cf8a9e0c5c6acc2a1e049be23 9], [http://git.kernel.org/linus/21f45020a3084f80fcdd5f056a0c6389f5406399 10)]

1.3. Btrfs updates

Btrfs allows different compression and copy-on-write settings for each file/directory (in addition to the per-filesystem controls). There is also the usual round of minor speedups, and tracepoints for runtime analysis.

Code: [http://git.kernel.org/linus/75e7cb7fe0c391561bd3af36515be3f3c64a04c6 (commit 1], [http://git.kernel.org/linus/32471f6e1983922473573da62cbee58699574aa4 2], [http://git.kernel.org/linus/c622ae6085d0c6ad834213bbf1477eb311359078 3], [http://git.kernel.org/linus/240f62c8756df285da11469259b3900f32883168 4], [http://git.kernel.org/linus/1abe9b8a138c9988ba8f7bfded6453649a31541f 5)]

1.4. Transcendent Memory

Recommended LWN article: [https://lwn.net/Articles/340080/ Transcendent memory]

Trascendent memory is a new type of memory with a particular set of characteristics. From LWN: "transcendental memory can be thought of as a sort of RAM disk with some interesting characteristics: nobody knows how big it is, writes to the disk may not succeed, and, potentially, data written to the disk may vanish before being read back again". This memory could be used in places like the page cache, swap, or virtualization. In this release it is used for to implement a compressed in-memory caching mechanism called zcache.

Code: [http://git.kernel.org/linus/daa6afa6d920a389015bb8f1ea519cef0636f528 (commit 1], [http://git.kernel.org/linus/9cc06bf88d554dd527ded26eab28eec6a0d0e3df 2], [http://git.kernel.org/linus/6630889735ec3d950b4f1496ada77df287d8ee1b 3)]

1.5. BKL: That's all, folks

In 2.6.37, it was possible to compile a Linux kernel without support for the BKL. In this release, the BKL has been removed completely from the kernel sources, including the functions lock_kernel() and unlock_kernel().

Code: [http://git.kernel.org/linus/4ba8216cd90560bc402f52076f64d8546e8aefcb (commit)]

1.6. Open-by-handle syscalls

Recommended LWN article: [https://lwn.net/Articles/375888/ Open by handle]

Two new syscalls have been added, name_to_handle_at() and open_by_handle_at(). These syscalls return a file handle, which is useful for user-space filesystems, backup software and other storage management tools. These handles can be used in a new flag that has been added to the open() syscall: O_PATH.

Code [http://git.kernel.org/linus/990d6c2d7aee921e3bce22b2d6a750fd552262be (commit)], [http://git.kernel.org/linus/becfd1f37544798cbdfd788f32c827160fab98c1 (commit)], [http://git.kernel.org/linus/7dadb755b082c259f7dd4a95a3a6eb21646a28d5 (commit)], [http://git.kernel.org/linus/6aae5f2b2085c5c90964bb78676ea8a6a336e037 (commit)], [http://git.kernel.org/linus/1abf0c718f15a56a0a435588d1b104c7a37dc9bd (commit)], [http://git.kernel.org/linus/bcda76524cd1fa32af748536f27f674a13e56700 (commit)]

2. Drivers and architectures

All the driver and architecture-specific changes can be found in the [http://kernelnewbies.org/Linux_2_6_38-DriversArch Linux_2_6_39-DriversArch page]

3. Core

4. CPU scheduler

5. Memory management

  • Add VM counters for transparent hugepages [http://git.kernel.org/linus/81ab4201fb7d91d6b0cd9ad5b4b16776e4bed145 (commit)]

  • vmap area cache (solves a regression introduced in [http://kernelnewbies.org/Linux_2_6_28#head-26b4ca97ca6bd51ffa63c361ae97552eb29d30e8 2.6.28] [http://git.kernel.org/linus/89699605fe7cfd8611900346f61cb6cbf179b10a (commit)]

  • Have smaps show transparent huge pages [http://git.kernel.org/linus/4031a219d8913da40ade5a6e5b538cc61e975cc8 (commit)]

6. Block

7. Networking

* net_sched: SFB flow scheduler [http://git.kernel.org/linus/e13e02a3c68d899169c78d9a18689bd73491d59a (commit)] * sched: CHOKe flow scheduler [http://git.kernel.org/linus/45e144339ac59971eb44be32e1282760aaabe861 (commit)]

  • Multi-queue priority scheduler (MQPRIO) net_sched: implement a root container qdisc sch_mqprio [http://git.kernel.org/linus/b8970f0bfc78103cb74c66055de7379b15097840 (commit)]

  • Implement mechanism for HW based QOS [http://git.kernel.org/linus/4f57c087de9b46182545676d2c594120a20f2e58 (commit)]

  • RPS: Enable hardware acceleration of RFS [http://git.kernel.org/linus/c445477d74ab3779d1386ab797fbb9b628eb9f64 (commit)]

  • UDP: Add lockless transmit path [http://git.kernel.org/linus/903ab86d195cca295379699299c5fc10beba31c7 (commit)]

  • Add support for IPsec extended sequence numbers (esn) as defined in RFC 4303 [http://git.kernel.org/linus/9736acf395d3608583a7be70f62800b494fa103c (commit 1], [http://git.kernel.org/linus/0dc49e9b28a7253ff05be2794d747f8ea5f1f423 2], [http://git.kernel.org/linus/d212a4c29096484e5e83b5006e695add126260af 3], [http://git.kernel.org/linus/2cd084678fc1eb75aec4f7ae3d339d232c00ec61 4], [http://git.kernel.org/linus/d8647b79c3b7e223ac051439d165bc8e7bbb832f 5)]

  • TX timestamps for IPv6 UDP packets [http://git.kernel.org/linus/a693e69897e7811e2790295f38a0ce3a92c4b45c (commit)]

  • netlink: support setting devgroup parameters [http://git.kernel.org/linus/e7ed828f10bd89a28f821ae7f20e691704d61923 (commit)]

Netfilter

  • Audit target to record accepted/dropped packets [http://git.kernel.org/linus/43f393caec0362abe03c72799d3f342af3973070 (commit)]

  • xtable: connlimit revision 1 [http://git.kernel.org/linus/cc4fc022571376412986e27e08b0765e9cb2aafb (commit)]

  • xtable: speedup compat operations [http://git.kernel.org/linus/255d0dc34068a976550ce555e153c0bfcfec7cc6 (commit)]

  • xtable: "set" match and "SET" target support [http://git.kernel.org/linus/d956798d82d2d331c031301965d69e17a1a48a2b (commit)]

  • xt_addrtype: ipv6 support [http://git.kernel.org/linus/2f5dc63123905a89d4260ab8ee08d19ec104db04 (commit)]

  • xt_CLASSIFY: add ARP support, allow CLASSIFY target on any table [http://git.kernel.org/linus/9811600f7c1f18152430c6b93b0a76fdd88a59ce (commit)]

  • xt_conntrack: support matching on port ranges [http://git.kernel.org/linus/b017900aac4a158b9bf7ffdcb8a369a91115b3e4 (commit)]

  • ebt_ip6: allow matching on ipv6-icmp types/codes [http://git.kernel.org/linus/6faee60a4e82075853a437831768cc9e2e563e4e (commit)]

  • nf_conntrack: nf_conntrack snmp helper [http://git.kernel.org/linus/93557f53e1fbd9e2b6574ab0a9b5852628fde9e3 (commit)]

  • nf_conntrack_tstamp: add flow-based timestamp extension [http://git.kernel.org/linus/a992ca2a0498edd22a88ac8c41570f536de29c9e (commit)]

8. File systems

9p

  • Add buffered write support for v9fs. [http://git.kernel.org/linus/7263cebed9fadad719063fdc8bba7085cf2c080d (commit)]

  • Add direct IO support in cached mode [http://git.kernel.org/linus/e959b54901e835f062ac8d44107bc543b66f0364 (commit)]

  • Add posixacl mount option [http://git.kernel.org/linus/e782ef71097e832f62256370a2fe231b9fba96cf (commit)]

GFS2

  • Deallocation performance patch [http://git.kernel.org/linus/4c16c36ad62fff8485215bd803d778eb2bd0b8bd (commit)]

  • Improve cluster mmap scalability [http://git.kernel.org/linus/b9c93bb7deadc7cdd00415edc6b38d67a26c1c7a (commit)]

  • Introduce AIL lock [http://git.kernel.org/linus/d6a079e82efd5fcbb1c7295f22e123c2cc748018 (commit)]

  • Use RCU for glock hash table [http://git.kernel.org/linus/bc015cb84129eb1451913cfebece270bf7a39e0f (commit)]

HPFS

  • Make HPFS compile on preempt and SMP [http://git.kernel.org/linus/637b424bf8747e50bab6648ab919632d6efd6c28 (commit)]

  • Implement fsync for hpfs [http://git.kernel.org/linus/bc8728ee56bca62df269b2dd159bc60838ac8e80 (commit)]

  • Remove CR/LF conversion option [http://git.kernel.org/linus/0fe105aa29bed0994991462b58ef61646db0e459 (commit)]

XFS

  • Enable delaylog by default [http://git.kernel.org/linus/20ad9ea9becd34a3c16252ca9d815f2c74f8f30f (commit)]

  • Stop using the page cache to back the buffer cache [http://git.kernel.org/linus/0e6e847ffe37436e331c132639f9f872febce82e (commit)]

9. Crypto

10. Virtualization

11. Security

SELinux

  • Make selinux cache VFS RCU walks safe [http://git.kernel.org/linus/9ade0cf440a1e5800dc68eef2e77b8d9d83a6dff (commit)]

  • Add a 4th criteria to object labeling: directory entry [http://git.kernel.org/linus/652bb9b0d6ce007f37c098947b2cc0c45efa3f66 (commit)]

12. Tracing/perf


CategoryReleases

  • MoinMoin Powered
  • Python Powered
  • GPL licensed
  • Valid HTML 4.01