Linux kernel source tree
Find a file
Linus Torvalds d42e504a55 Update to the time/timers core:
- Prevent a thundering herd problem when the timekeeper CPU is delayed
     and a large number of CPUs compete to acquire jiffies_lock to do the
     update. Limit it to one CPU with a separate "uncontended" atomic
     variable.
 
   - A set of improvements for the timer migration mechanism:
 
     - Support imbalanced NUMA trees correctly
 
     - Support dynamic exclusion of CPUs from the migrator duty to allow the
       cpuset/isolation mechanism to exclude them from handling timers of
       remote idle CPUs.
 
    - The usual small updates, cleanups and enhancements
 -----BEGIN PGP SIGNATURE-----
 
 iQJHBAABCgAxFiEEQp8+kY+LLUocC4bMphj1TA10mKEFAmks7doTHHRnbHhAbGlu
 dXRyb25peC5kZQAKCRCmGPVMDXSYoaxrD/40nxx+8cEXsVbVLIkP2PQbd2Y8+7sk
 YbNu/Cb7j7Bg7R8YIs4p5GHk+7Yt/hNsW77SmbAzRPUyYYG6L3bUYlBa3yQlvIuo
 xRPbzGA+RJies9skIGHbQ8z6ig1zUASRJPcBYiuaVIAuQhCfLNc4Nii9cEWtjZ24
 +5gfRwV+vy74ArWwRkwaGejDK1tav+gd62OkFQZC8WtjQ08ozGZ6VBJNg7nYq/gH
 FYO1rH2tQ/ZyjlO/x5NF8gFcjYD8iv5PDp8oH35MPx+XTdDccf0G3QB7ug0ffVdV
 b4gA6lZTAmpsu/NHb6ByN4i/kf3wf8la/i+EaAh/Ov7NW078gunvVKVA7jStcbBl
 ZgG5SRHiKRvQF/WXLGVQAnilRDZwRuS0nmJlqfExa44v23l5o3768RwdRYwQlv8g
 X5KSRl0jlVgVtZHgNBlZtgX9+rnQSr9sB5sVGBP2a6a1WhVXQV/2kp0wjdnU0mPw
 jLCnSdsHqBlSf9V7O/na823WCnBFb7blrLBXUoSbHBnICqtVFzhE1kBXWw3S7Kqh
 CiaWM+S4WfR0HRnUlWMTS8BZ82MgiDnd7nGUXWwXBbdqWmoj/9CoU6SZRjbMBkzi
 EY1XvmoYf6eSzdxfydI1hFi0/bbb8K9umHQlrpW3HeN9uXnVc0/+TroVPLuaKUdi
 53ClqXjzE+CpJg==
 =lQKn
 -----END PGP SIGNATURE-----

Merge tag 'timers-core-2025-11-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull timer core updates from Thomas Gleixner:

 - Prevent a thundering herd problem when the timekeeper CPU is delayed
   and a large number of CPUs compete to acquire jiffies_lock to do the
   update. Limit it to one CPU with a separate "uncontended" atomic
   variable.

 - A set of improvements for the timer migration mechanism:

     - Support imbalanced NUMA trees correctly

     - Support dynamic exclusion of CPUs from the migrator duty to allow
       the cpuset/isolation mechanism to exclude them from handling
       timers of remote idle CPUs

 - The usual small updates, cleanups and enhancements

* tag 'timers-core-2025-11-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  timers/migration: Exclude isolated cpus from hierarchy
  cpumask: Add initialiser to use cleanup helpers
  sched/isolation: Force housekeeping if isolcpus and nohz_full don't leave any
  cgroup/cpuset: Rename update_unbound_workqueue_cpumask() to update_isolation_cpumasks()
  timers/migration: Use scoped_guard on available flag set/clear
  timers/migration: Add mask for CPUs available in the hierarchy
  timers/migration: Rename 'online' bit to 'available'
  selftests/timers/nanosleep: Add tests for return of remaining time
  selftests/timers: Clean up kernel version check in posix_timers
  time: Fix a few typos in time[r] related code comments
  time: tick-oneshot: Add missing Return and parameter descriptions to kernel-doc
  hrtimer: Store time as ktime_t in restart block
  timers/migration: Remove dead code handling idle CPU checking for remote timers
  timers/migration: Remove unused "cpu" parameter from tmigr_get_group()
  timers/migration: Assert that hotplug preparing CPU is part of stable active hierarchy
  timers/migration: Fix imbalanced NUMA trees
  timers/migration: Remove locking on group connection
  timers/migration: Convert "while" loops to use "for"
  tick/sched: Limit non-timekeeper CPUs calling jiffies update
2025-12-02 09:58:33 -08:00
arch Updates for the interrupt core and treewide cleanups: 2025-12-02 09:14:26 -08:00
block vfs-6.19-rc1.inode 2025-12-01 09:02:34 -08:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto This push contains the following changes: 2025-10-10 08:56:16 -07:00
Documentation Updates for clocksource and clockevent drivers: 2025-12-02 09:54:27 -08:00
drivers Updates for clocksource and clockevent drivers: 2025-12-02 09:54:27 -08:00
fs A large overhaul of the restartable sequences and CID management: 2025-12-02 08:48:53 -08:00
include Update to the time/timers core: 2025-12-02 09:58:33 -08:00
init A large overhaul of the restartable sequences and CID management: 2025-12-02 08:48:53 -08:00
io_uring vfs-6.19-rc1.fd_prepare.fs 2025-12-01 17:32:07 -08:00
ipc vfs-6.19-rc1.fd_prepare.fs 2025-12-01 17:32:07 -08:00
kernel Update to the time/timers core: 2025-12-02 09:58:33 -08:00
lib Two small updates for debugobjects: 2025-12-02 09:07:48 -08:00
LICENSES LICENSES: Replace the obsolete address of the FSF in the GFDL-1.2 2025-07-24 11:15:39 +02:00
mm vfs-6.19-rc1.fd_prepare.fs 2025-12-01 17:32:07 -08:00
net Scoped user mode access and related changes: 2025-12-02 08:01:39 -08:00
rust Locking updates for v6.19: 2025-12-01 19:50:58 -08:00
samples Locking updates for v6.19: 2025-12-01 19:50:58 -08:00
scripts objtool updates for v6.19: 2025-12-01 20:18:59 -08:00
security vfs-6.19-rc1.directory.locking 2025-12-01 16:13:46 -08:00
sound ALSA: hda/realtek: Add quirk for HP ProBook 450 G8 2025-11-26 07:26:56 +01:00
tools Update to the time/timers core: 2025-12-02 09:58:33 -08:00
usr gen_init_cpio: Ignore fsync() returning EINVAL on pipes 2025-10-07 09:53:05 -07:00
virt A large overhaul of the restartable sequences and CID management: 2025-12-02 08:48:53 -08:00
.clang-format memblock: drop for_each_free_mem_pfn_range_in_zone_from() 2025-09-14 08:49:03 +03:00
.clippy.toml rust: clean Rust 1.88.0's warning about clippy::disallowed_macros configuration 2025-05-07 00:11:47 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore MAINTAINERS: remove Alyssa Rosenzweig 2025-09-18 21:17:31 +02:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore .gitignore: ignore compile_commands.json globally 2025-08-12 15:53:55 -07:00
.mailmap 8 hotfixes. 4 are cc:stable, 7 are against mm/. 2025-11-26 12:38:05 -08:00
.pylintrc tools: docs: parse-headers.py: move it from sphinx dir 2025-08-29 15:54:42 -06:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: mark ISDN subsystem as orphan 2025-10-27 17:49:45 -07:00
Kbuild sched: Make migrate_{en,dis}able() inline 2025-09-25 09:57:16 +02:00
Kconfig io_uring: Rename KConfig to Kconfig 2025-02-19 14:53:27 -07:00
MAINTAINERS Updates for clocksource and clockevent drivers: 2025-12-02 09:54:27 -08:00
Makefile vfs-6.19-rc1.misc 2025-12-01 08:44:26 -08:00
README README: Fix spelling 2024-03-18 03:36:32 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.