mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2026-08-30 19:13:03 -04:00
3b4128b9f3
Pull timer and timekeeping core updates from Thomas Gleixner: - Fix a subtly inconsistency in the timekeeping code, which fails to account for the monotonicity adjustment in ntp_error. For small changes of the clocksource multiplicator (+/-1) which are typically used by the NTP PLL this is hard to observe. But for larger adjustments, e.g. caused by a direct frequency setting through adjtimex() the one-time uncompensated offset is significant. Cure this by adjusting ntp_error with the resulting offset so that the discrepancy is smoothed away over time - Make tick length calculations correct in NTP. The timekeeping core takes the quantisation of the clocksource into account when calculating the tick length to compensate for the deviation of the nominal NTP_INTERVAL_LENGTH. While timekeeping gets this right, NTP is not aware of that, which means it operates on the nominal value and not on the actual value which is determined by the clock source frequency. The rounding of a coarse clocksource like the ACPI PM timer results in a +127 PPM deviation. Cure this by exposing the deviation to the NTP code so that it can operate on the same data as the timekeeping core. This is purely kernel internal. User space still sees the nominal tick lenght via adjtimex(). - The accuracy of the NTP adjustments is fairly approximate as the code assumes that the invocations are precisely in NTP interval frequency ticks and the final adjustment can over and under-run. Cure this by adjusting ntp_error by the intended skew on each tick to achieve the desired rate. - Handle the two competing skews of time offset and time adjustment correctly by calculating the conflict portion between the skews and adjusting both accordingly. - A set of updates and improvements for the selftests - The usual small fixes and improvements all over the place * tag 'timers-core-2026-08-17' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (58 commits) selftests: timers: nsleep-lat: Check all calls to clock_nanosleep() and clock_gettime() selftests: timers: nsleep-lat: Reuse kselftest error numbers selftests: timers: nsleep-lat: Explicitly list the tested clocks selftests: timers: nsleep-lat: Use NSEC_PER_MSEC define for unreasonable latency selftests: timers: nanosleep: Report each test separately selftests: timers: nanosleep: Explicitly handle timer_delete() failure selftests: timers: nanosleep: Move all single clock tests out of the loop in main() selftests: timers: nanosleep: Reuse kselftest error numbers selftests: timers: nanosleep: Explicitly list the tested clocks selftests: timers: nanosleep: Drop output alignment selftests: timers: Use clock_name() and constants from clock-helpers.h selftests: Add clock-helpers.h timer_list: Use ktime_t over nanoseconds timer_list: Use standard 'long long' format placeholders hrtimer: Add a lockdep assertion to hrtimer_update_base() timekeeping: Use u32 for clock_was_set_seq timekeeping: Rename clockid_aux_valid() to clockid_is_aux_clock() hrtimer: Account nr_retries on recovered interrupt retries timers/itimer: Zero-init old itimerval before copy to userspace nohz: Replace dead select with choice default ...
Linux kernel ============ The Linux kernel is the core of any Linux operating system. It manages hardware, system resources, and provides the fundamental services for all other software. Quick Start ----------- * Report a bug: See Documentation/admin-guide/reporting-issues.rst * Get the latest kernel: https://kernel.org * Build the kernel: See Documentation/admin-guide/quickly-build-trimmed-linux.rst * Join the community: https://lore.kernel.org/ Essential Documentation ----------------------- All users should be familiar with: * Building requirements: Documentation/process/changes.rst * Code of Conduct: Documentation/process/code-of-conduct.rst * License: See COPYING Documentation can be built with make htmldocs or viewed online at: https://www.kernel.org/doc/html/latest/ Who Are You? ============ Find your role below: * New Kernel Developer - Getting started with kernel development * Academic Researcher - Studying kernel internals and architecture * Security Expert - Hardening and vulnerability analysis * Backport/Maintenance Engineer - Maintaining stable kernels * System Administrator - Configuring and troubleshooting * Maintainer - Leading subsystems and reviewing patches * Hardware Vendor - Writing drivers for new hardware * Distribution Maintainer - Packaging kernels for distros * AI Coding Assistant - LLMs and AI-powered development tools For Specific Users ================== New Kernel Developer -------------------- Welcome! Start your kernel development journey here: * Getting Started: Documentation/process/development-process.rst * Your First Patch: Documentation/process/submitting-patches.rst * Coding Style: Documentation/process/coding-style.rst * Build System: Documentation/kbuild/index.rst * Development Tools: Documentation/dev-tools/index.rst * Kernel Hacking Guide: Documentation/kernel-hacking/hacking.rst * Core APIs: Documentation/core-api/index.rst Academic Researcher ------------------- Explore the kernel's architecture and internals: * Researcher Guidelines: Documentation/process/researcher-guidelines.rst * Memory Management: Documentation/mm/index.rst * Scheduler: Documentation/scheduler/index.rst * Networking Stack: Documentation/networking/index.rst * Filesystems: Documentation/filesystems/index.rst * RCU (Read-Copy Update): Documentation/RCU/index.rst * Locking Primitives: Documentation/locking/index.rst * Power Management: Documentation/power/index.rst Security Expert --------------- Security documentation and hardening guides: * Security Documentation: Documentation/security/index.rst * LSM Development: Documentation/security/lsm-development.rst * Self Protection: Documentation/security/self-protection.rst * Reporting Vulnerabilities: Documentation/process/security-bugs.rst * CVE Procedures: Documentation/process/cve.rst * Embargoed Hardware Issues: Documentation/process/embargoed-hardware-issues.rst * Security Features: Documentation/userspace-api/seccomp_filter.rst Backport/Maintenance Engineer ----------------------------- Maintain and stabilize kernel versions: * Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst * Backporting Guide: Documentation/process/backporting.rst * Applying Patches: Documentation/process/applying-patches.rst * Subsystem Profile: Documentation/maintainer/maintainer-entry-profile.rst * Git for Maintainers: Documentation/maintainer/configure-git.rst System Administrator -------------------- Configure, tune, and troubleshoot Linux systems: * Admin Guide: Documentation/admin-guide/index.rst * Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst * Sysctl Tuning: Documentation/admin-guide/sysctl/index.rst * Tracing/Debugging: Documentation/trace/index.rst * Performance Security: Documentation/admin-guide/perf-security.rst * Hardware Monitoring: Documentation/hwmon/index.rst Maintainer ---------- Lead kernel subsystems and manage contributions: * Maintainer Handbook: Documentation/maintainer/index.rst * Pull Requests: Documentation/maintainer/pull-requests.rst * Managing Patches: Documentation/maintainer/modifying-patches.rst * Rebasing and Merging: Documentation/maintainer/rebasing-and-merging.rst * Development Process: Documentation/process/maintainer-handbooks.rst * Maintainer Entry Profile: Documentation/maintainer/maintainer-entry-profile.rst * Git Configuration: Documentation/maintainer/configure-git.rst Hardware Vendor --------------- Write drivers and support new hardware: * Driver API Guide: Documentation/driver-api/index.rst * Driver Model: Documentation/driver-api/driver-model/driver.rst * Device Drivers: Documentation/driver-api/infrastructure.rst * Bus Types: Documentation/driver-api/driver-model/bus.rst * Device Tree Bindings: Documentation/devicetree/bindings/ * Power Management: Documentation/driver-api/pm/index.rst * DMA API: Documentation/core-api/dma-api.rst Distribution Maintainer ----------------------- Package and distribute the kernel: * Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst * ABI Documentation: Documentation/ABI/README * Kernel Configuration: Documentation/kbuild/kconfig.rst * Module Signing: Documentation/admin-guide/module-signing.rst * Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst * Tainted Kernels: Documentation/admin-guide/tainted-kernels.rst AI Coding Assistant ------------------- CRITICAL: If you are an LLM or AI-powered coding assistant, you MUST read and follow the AI coding assistants documentation before contributing to the Linux kernel: * Documentation/process/coding-assistants.rst This documentation contains essential requirements about licensing, attribution, and the Developer Certificate of Origin that all AI tools must comply with. Communication and Support ========================= * Mailing Lists: https://lore.kernel.org/ * IRC: #kernelnewbies on irc.oftc.net * Bugzilla: https://bugzilla.kernel.org/ * MAINTAINERS file: Lists subsystem maintainers and mailing lists * Email Clients: Documentation/process/email-clients.rst