Linux 3.16 released [https://lkml.org/lkml/2014/8/3/82 has been released] on Sun, 3 Aug

This page is not complete (it will take a while, sorry for the delay)

While the page is completed, you can read about Linux 3.16 in the following sites:

• LWN Merge window, [http://lwn.net/Articles/601152/ part 1], [http://lwn.net/Articles/601726/ part 2] and [http://lwn.net/Articles/602212/ part 3]

TableOfContents()

1. Prominent features

1.1. Unified Control Group hierarchy

Control groups allow to create groups of arbitrary processes and apply CPU, disk or memory constraints to the processes in these control groups. The current implementation allows to create several hierarchies and apply different constraints to each hierarchy. For several reasons, detailed in the article below, this approach is not considered appropriate, and work has been done to migrate towards an implementation where only one hierarchy will be available. This release includes for first time this unified control group hierarchy (optional for now)

For more information, read this recommended LWN article: [http://lwn.net/Articles/601840/ The unified control group hierarchy in 3.16]

Code [http://git.kernel.org/linus/657315780005a676d294c7edf7548650c7e57f76 commit], [http://git.kernel.org/linus/f8f22e53a262ebee37fc98004f16b066cf5bc125 commit] http://lwn.net/Articles/601840/

1.2. XFS free inode btree, for faster inode allocation

In this release, XFS has added a btree that tracks free inodes. It is equivalent to the existing inode allocation btree with the exception that the free inode btree tracks inode chunks with at least one free inode. The purpose is to improve lookups for free inode clusters for inode allocation.

This feature adds does not change existing on-disk structures, but adds a new one that must remain consistent with the inode allocation btree; for this reason older kernels will only be able to mount read-only filesystems with the free inode btree feature.

Code: [https://git.kernel.org/linus/412dd3a6daf0cadce1b2d6a34fa3713f40255579 merge commit]

1.3. TCP Fast Open server mode on IPv6 support

TCP Fast Open is a [http://lwn.net/Articles/508865/ TCP feature] designed to make TCP connections faster. First support was [http://kernelnewbies.org/Linux_3.6#head-ac78950a7b57d92d5835642926f0e147c680b99c added on Linux 3.6] for clients, in 3.7 support was [http://kernelnewbies.org/Linux_3.7 added for servers] and in 3.13 Fast Open was [http://kernelnewbies.org/Linux_3.13#head-159ff61ea3acfd67b88855e75dbbb140f8825c4a enabled by default]. This release adds Fast Open support for IPv6 for servers.

Code: [http://git.kernel.org/linus/3a19ce0eec32667b835d8dc887002019fc6b3a02 commit]

2. Drivers and architectures

All the driver and architecture-specific changes can be found in the [http://kernelnewbies.org/Linux_3.16-DriversArch Linux_3.16-DriversArch page]

3. Core

• IPC System V shared memory: increase the defaults for SHMALL, SHMMAX [http://git.kernel.org/linus/060028bac94bf60a65415d1d55a359c3a17d5c31 commit]

• locking

  • Introduce 'qrwlocks' - fair, queued rwlocks [https://git.kernel.org/linus/70af2f8a4f48d6cebdf92d533d3aef37853ce6de commit]

  • rwsem: Support optimistic spinning [https://git.kernel.org/linus/4fc828e24cd9c385d3a44e1b499ec7fc70239d8a commit]

• fanotify: create FAN_ACCESS event for readdir [https://git.kernel.org/linus/d4c7cf6cffb1bc711a833b5e304ba5bcfe76398b commit]

• Add "crash_kexec_post_notifiers" option for kdump after panic_notifers [https://git.kernel.org/linus/f06e5153f4ae2e2f3b0300f0e260e40cb7fefd45 commit]

• Add initcall_blacklist kernel parameter [https://git.kernel.org/linus/7b0b73d76651e5f88c88b76efa18d719f832bf6f commit]

• seccomp: use internal BPF JIT to speed up filters [http://git.kernel.org/linus/8f577cadf7181243d336be9aba40c1bcc02c4c54 commit]

• Add generic PCI host controller driver [https://git.kernel.org/linus/ce292991d88b77160f348fb8a3a2cf6e78f4b456 commit]

• Virtual terminal: emulate 8- and 24-bit colour codes. [http://git.kernel.org/linus/cec5b2a97a11ade56a701e83044d0a2a984c67b4 commit]

• Add CONFIG_SGETMASK_SYSCALL option to optionally disable sys_sgetmask/sys_ssetmask syscalls, which are no longer supported by older libcs[http://git.kernel.org/linus/f6187769dae48234f3877df3c4d99294cc2254fa commit]

• proc: Allow for strict write position handling [http://git.kernel.org/linus/f4aacea2f5d1a5f7e3154e967d70cf3f711bcd61 commit]

4. Memory management

• hugetlb: add support for gigantic page allocation at runtime instead of just at boot time [https://git.kernel.org/linus/944d9fec8d7aee3f2e16573e9b6a16634b33f403 commit]

• Introduce a CONFIG_DEBUG_VM_VMACACHE option to enable counting the cache hit rate -- exported in /proc/vmstat [http://git.kernel.org/linus/4f115147ff802267d0aa41e361c5aa5bd933d896 commit]

• Disable zone_reclaim_mode by default [http://git.kernel.org/linus/4f9b16a64753d0bb607454347036dc997fd03b82 commit]

• memcontrol cgroup: remove hierarchy restrictions for swappiness and oom_control [http://git.kernel.org/linus/3dae7fec5e884a4e72e5416db0894de66f586201 commit]

• non-atomically mark page accessed during page cache allocation where possible [http://git.kernel.org/linus/2457aec63745e235bcafb7ef312b182d8682f0fc commit]

• Only force scan in reclaim when none of the LRUs are big enough. [http://git.kernel.org/linus/6f04f48dc9c0433e2bb687f5f7f7af1aba97b04d commit]

• Use proportional scanning during direct reclaim and full scan at DEF_PRIORITY [http://git.kernel.org/linus/1a501907bbea8e6ebb0b16cf6db9e9cbf1d2c813 commit]

5. Block layer

• lots of development effort has gone into [http://kernelnewbies.org/Linux_3.13#head-3e5f0c2bcebc98efd197e3036dd814eadd62839c blk-mq] in the last 3 months. It's heading to where 3.16 will be a feature complete and performant blk-mq

• raid5: speedup sync_request processing (speeds up rebuild speed) [http://git.kernel.org/linus/053f5b6525ae32da397e6c47721961f800d2c924 commit]

• raid5: add an option to avoid copy data from bio to stripe cache (in 1M randwrite tests, avoid the copy can increase the performance more than 30%) [http://git.kernel.org/linus/d592a9969141e67a3874c808999a4db4bf82ed83 commit]

• rbd: add ioctl for blockdev command compatibility [http://git.kernel.org/linus/131fd9f6fc89ad2cc993f80664d18ca49d6f8483 commit]

• ore: Support for raid 6 [http://git.kernel.org/linus/ce5d36aac26cc395fe3bc45525cdbad3644f01e5 commit]

6. Power management

• cpufreq

  • Add support for intermediate (stable) frequencies for platforms that may temporarily switch to a stable frequency while transitioning between frequencies [https://git.kernel.org/linus/1c03a2d04d7ab6d27c1fef8614f08187d974bd21 commit]

  • governor: Improve performance of latency-sensitive bursty workloads [https://git.kernel.org/linus/18b46abd0009516c1973a57ccf4d01b9eaa3422a commit]

• Introduce "nohibernate" boot parameter to disable both hibernation and resume at boot time - useful to use kernel features that are not compatible with hibernation [https://git.kernel.org/linus/a6e15a39048ec3229b9a53425f4384f55f6cc1b3 commit]

• Introduce command line argument, relative_sleep_states, that allows to change the way in which the kernel assigns labels to system sleep states [https://git.kernel.org/linus/0399d4db3edf5c58b6ec7f672f089f5085e49ed5 commit]

7. File systems

• Btrfs

  • New ioctl TREE_SEARCH_V2: it allows the user to supply a buffer of varying size in which a tree search can store its results. This is much more flexible if you want to receive items which are larger than the current fixed buffer of 3992 bytes or if you want to fetch more items at once. Items larger than this buffer are for example some of the type EXTENT_CSUM [http://git.kernel.org/linus/cc68a8a5a4330a4bb72922d0c7a7044ae13ee692 commit]

  • Don't restrict DEV_INFO ioctl to CAP_SYSADMIN [http://git.kernel.org/linus/7d6213c5a764d0591afeb9faa3f7ee18e8e74c25 commit]

  • Don't restrict FS_INFO ioctl to CAP_SYSADMIN [http://git.kernel.org/linus/e4ef90ff6198ac58d4c7dbbeae8cc7b24867d1ca commit]

  • Retrieve more info from FS_INFO ioctl [http://git.kernel.org/linus/80a773fbfc2d6b5b2478377e8ac271d495f55e73 commit]

  • Export more from FS_INFO to sysfs [http://git.kernel.org/linus/df93589a17378277c0ac394858dd8a2a41e5fb5a commit]

  • Reclaim the reserved metadata space at background (improves performance in some cases) [http://git.kernel.org/linus/21c7e75654b77b53a4436bf28496aac11536b6ba commit]

  • async delayed refs: Allows to batch delayed extent operations [http://git.kernel.org/linus/a79b7d4b3e8118f265dcb4bdf9a572c392f02708 commit]

  • rework qgroup accounting [http://git.kernel.org/linus/fcebe4562dec83b3f8d3088d77584727b09130b2 commit]

• XFS

  • Add filestream allocator tracepoints [http://git.kernel.org/linus/b94acd4786dce4379e986e6d58bdd74f8986af2f commit]

  • Turn NLINK feature on by default [http://git.kernel.org/linus/263997a6842b27a49f42bd795c5dd12242917b22 commit]

• F2FS

  • Large volume support [https://git.kernel.org/linus/1dbe4152168d44fa164edbdc9f1243de70b98f7a commit]

  • Support SEEK_{DATA, HOLE} in llseek [https://git.kernel.org/linus/267378d4de696d4397cd611e62957d19b2a61357 commit]

• FAT

  • Add support for DOS 1.x formatted volumes [https://git.kernel.org/linus/190a8843ded231638d0e7ae7d8ca6a712472d114 commit]

8. Networking

• Add support to configure SR-IOV VF minimum and maximum transmission rate through ip tool [http://git.kernel.org/linus/ed616689a3d95eb6c9bdbb1ef74b0f50cbdf276a commit]

• ipv6: setting IFA_F_MANAGETEMPADDR with RTM_DELADDR will indicate that the kernel should delete all related temporary addresses (similar to using IFA_F_MANAGETEMPADDR with RTM_NEWADDR [http://git.kernel.org/linus/6046d5b4e464ba9b2cc8f0407069456624598dd5 commit]

• l2tp: Add support for zero IPv6 checksums [http://git.kernel.org/linus/6b649feafe10b293f4bd5a74aca95faf625ae525 commit]

• Wireless

  • Support for dynamic channel bandwidth changes (e.g., HT 20/40 MHz changes)[http://git.kernel.org/linus/3b1700bde4f03ca68b058257f54d744cc8c84c72 commit]

• macvlan: Support bonding events [http://git.kernel.org/linus/4c9912556867bf89e7bb6946fd218a40b1d12139 commit]

• macvlan: add netpoll support [http://git.kernel.org/linus/688cea83f4396fa98b77a126ed278b89daccccdc commit]

• Add Generic Segmentation Offload support for UDP tunnels with checksum [http://git.kernel.org/linus/0f4f4ffa7b7c3d29d0537a126145c9f8d8ed5dbc commit]

• Implemement zero RX checksums for UDP/IPv6 ([http://tools.ietf.org/html/rfc6936 RFC 6936]). RFC 6936 relaxes the requirement of RFC 2460 that UDP/IPv6 packets which are received with a zero UDP checksum value must be dropped. RFC 6936 allows zero checksums to support tunnels over UDP [http://git.kernel.org/linus/4068579e1e098fa81d48db9ba4432ab664c58561 commit]

• Kernel-originated IP packets that have no user socket associated with them (e.g., ICMP errors and echo replies, TCP RSTs, etc.) are emitted with a mark of zero. Add a sysctl to make them have the same mark as the packet they are replying to [http://git.kernel.org/linus/e110861f86094cd78cc85593b873970092deb43a commit]

• When using mark-based routing, sockets returned from accept() may need to be marked differently depending on the incoming connection request. This patch adds a sysctl to mark TCP sockets based on the fwmark of the incoming SYN packet. If enabled, and an unmarked socket receives a SYN, then the SYN packet's fwmark is written to the connection's inet_request_sock, and later written back to the accepted socket when the connection is established. If the socket already has a nonzero mark, then the behaviour is the same as it is today, i.e., the listening socket's fwmark is used [http://git.kernel.org/linus/84f39b08d7868ce10eeaf640627cb89777f0ae93 commit]

tcp: Add a TCP_FASTOPEN socket option to get a max backlog on its listner [http://git.kernel.org/linus/1536e2857bd38e3bcd19963fd6b3c3287b4747c4 commit]

• tipc: add ioctl to fetch link names [http://git.kernel.org/linus/78acb1f9b898e85fa2c1e28e700b54b66b288e8d commit]

• tipc: add support for link state subscriptions [http://git.kernel.org/linus/a89778d8baf19cd7e728d81121a294a06cedaad1 commit]

• sctp: add support for busy polling to sctp protocol [http://git.kernel.org/linus/8465a5fcd1ceba8f2b55121d47b73f4025401490 commit]

• vxlan: Add support for UDP checksums (v4 sending, v6 zero csums) [http://git.kernel.org/linus/359a0ea9875ef4f32c8425bbe1ae348e1fd2ed2a commit], add x-netns support [http://git.kernel.org/linus/f01ec1c017dead42092997a2b8684fcab4cbf126 commit]

• tunnels - enable module autoloading [http://git.kernel.org/linus/f98f89a0104454f35a62d681683c844f6dbf4043 commit]

• netfilter

  • nf_tables: allow to delete several objects from a batch [http://git.kernel.org/linus/4fefee570d8e35d950e6b7294618e2035e669308 commit]

  • nfnetlink: Adding quota support to accounting framework [http://git.kernel.org/linus/683399eddb9fff742b1a14c5a5d03e12bfc0afff commit]

• ethtool: Support for configurable RSS hash key [https://git.kernel.org/linus/3de0b592394d17b2c41a261a6a493a521213f299 commit]

• bonding: Support macvlans on top of TLB/RLB mode bonds [https://git.kernel.org/linus/14af9963ba1e5e8400c9de9267bdcab895109f6a commit]

• bridge: Automatically manage port promiscuous mode [https://git.kernel.org/linus/f3a6ddf15209cfad90b83e04168f42a5d9c8cc17 commit], [https://git.kernel.org/linus/2796d0c648c940b4796f84384fbcfb0a2399db84 commit]

• bridge: Add 802.1ad tx VLAN acceleration [https://git.kernel.org/linus/1c5abb6c77a2e79537373143d2c1708e40b9f6ca commit]

• bridge: Support 802.1ad VLAN filtering [https://git.kernel.org/linus/204177f3f30c2dbd2db0aa62b5e9cf9029786450 commit]

• Bluetooth: Perform directed advertising support through connect() when we're in peripheral mode [https://git.kernel.org/linus/3c857757ef6e5a4e472bd3e5c934709c2eb482af commit]

• NFC: Add RAW socket type support for SOCKPROTO_RAW to read RAW NFC frames [https://git.kernel.org/linus/57be1f3f3ec1ccab6432615ca161c4c9ece2a2aa commit]

• Wireless

  • Add an option to hint the wireless core that the user is operating in an indoor environment [https://git.kernel.org/linus/52616f2b446eaad8eb2cd78bbd052f0066069757 commit]

• cfg80211: Support multiple CSA counters [https://git.kernel.org/linus/9a774c78e2114c7e8605e3a168ccd552cbe3d922 commit]

• Allow userspace to take ownership of interfaces. If an interface is owned by a netlink socket, then it will be destroyed if the netlink socket is closed for any reason, including if the process it belongs to crashed. This gives us a race-free way to get rid of any such interfaces [https://git.kernel.org/linus/78f22b6a3a9254460d23060530b48ae02a9394e3 commit]

9. Virtualization

• hyperv: Add support for virtual Receive Side Scaling (vRSS) [https://git.kernel.org/linus/5b54dac856cb5bd6f33f4159012773e4a33704f7 commit]

• xen-netback: Add support for multiple queues [http://git.kernel.org/linus/8d3d53b3e43363e79ab9a9ecc149b06c1314b25d commit]

• xen-netfront: Add support for multiple queues [http://git.kernel.org/linus/50ee60611bf0c7328e5cae438ea5c26590f3f747 commit]

• virtio-rng: support multiple virtio-rng devices [http://git.kernel.org/linus/08e53fbdb85c0f6f45c0f7c1ea3defc1752a95ce commit]

10. Tracing/perf

• Allow probing on some kprobes and ftrace functions [https://git.kernel.org/linus/fbc1963d2c1c4eb4651132a2c5c9d6111ada17d3 commit]

• Add tracepoint benchmark tracepoint [http://git.kernel.org/linus/81dc9f0ef21e40114cc895894c7acf3055f6d1fb commit]

• perf

  • Add conditional branch filter 'cond' to perf record [http://git.kernel.org/linus/0fffa5df4cf3e22be4f40f6698ab9e49f3ffd6fa commit], [http://git.kernel.org/linus/37548914fbfcd56e1955a9b7e55dc3b84a3e9e25 commit], [http://git.kernel.org/linus/3e39db4ae2a92ae9e338e8066411b694b0edcb31 commit]

  • diff: Add --percentage option [http://git.kernel.org/linus/8810f6ced73556c1a63b6269a6cdad8d630aaaf0 commit]

  • report: Add --children option [http://git.kernel.org/linus/793aaaabb79803a0154fc6a98c472a29bb6d5cc9 commit], add --percentage option [http://git.kernel.org/linus/f2148330544a697481219b5bc34261f6dd049bfb commit], add -F option to specify output fields [http://git.kernel.org/linus/a7d945bc91602f916d2d0c794c179d9a784859e7 commit], add report.children config option [http://git.kernel.org/linus/8d8e645ceafd726b8317949f899e4b3acfb20d29 commit]

  • Add dcacheline sort [http://git.kernel.org/linus/9b32ba71ba905b90610fc2aad77cb98a373c5624 commit]

  • Add hist.percentage config option [http://git.kernel.org/linus/0b93da1756df4fe930ee0220a6addce263a6e0ab commit]

  • Allow hpp fields to be sort keys [http://git.kernel.org/linus/a2ce067e55e328f1a6fe3dddf77a173381ffdfe1 commit]

  • top: Add --children option [http://git.kernel.org/linus/1432ec342ece6a7ef78825ae3a9ba1c91686f71d commit], add --fields option to specify output fields [http://git.kernel.org/linus/6fe8c26d7ab9fbd6748fc40ca5fea1e3131e7236 commit], add --percentage option [http://git.kernel.org/linus/33db4568e1f41efe6d0e4695483f968fc1135bf3 commit], add top.children config option [http://git.kernel.org/linus/104ac991bd821773cba6f262f97a4a752ed76dd5 commit]

  • tui: Add 'F' hotkey to toggle percentage output [http://git.kernel.org/linus/105eb30f18197a217695eac4ddf87526f2cba867 commit]

11. Security

• Smack: adds smackfs/ptrace interface [https://git.kernel.org/linus/668678185247303450e60df14569f94cf5775fea commit]

• Smack: Verify read access on file open - v3 [https://git.kernel.org/linus/a6834c0b9114c06106efee8e9f2a11fbbb104567 commit]

• audit: add netlink multicast socket with one group to kaudit for "best-effort" delivery to read-only userspace clients such as systemd [https://git.kernel.org/linus/451f921639fea4600dfb9ab2889332bdcc7b48d3 commit]

• ima: audit log files opened with O_DIRECT flag [https://git.kernel.org/linus/f9b2a735bdddf836214b5dca74f6ca7712e5a08c commit]

12. Crypto

13. Other news sites that track the changes of this release

• LWN Merge window, [http://lwn.net/Articles/601152/ part 1], [http://lwn.net/Articles/601726/ part 2] and [http://lwn.net/Articles/602212/ part 3]