Changes in timerqueue.c

0fc8f6200d2313278fbf4539bbab74677c685531 - Merge drm/drm-fixes into drm-misc-fixes

Mon, 27 Apr 2026 08:26:49 +0000

Merge drm/drm-fixes into drm-misc-fixesGetting fixes and updates from v7.1-rc1.Signed-off-by: Thomas Zimmermann List of files: /linux/lib/timerqueue.c

c1fe867b5bf9c57ab7856486d342720e2b205eed - Merge tag 'timers-core-2026-04-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Tue, 14 Apr 2026 17:27:07 +0000

Merge tag 'timers-core-2026-04-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tipPull timer core updates from Thomas Gleixner: - A rework of the hrtimer subsystem to reduce the overhead for frequently armed timers, especially the hrtick scheduler timer: - Better timer locality decision - Simplification of the evaluation of the first expiry time by keeping track of the neighbor timers in the RB-tree by providing a RB-tree variant with neighbor links. That avoids walking the RB-tree on removal to find the next expiry time, but even more important allows to quickly evaluate whether a timer which is rearmed changes the position in the RB-tree with the modified expiry time or not. If not, the dequeue/enqueue sequence which both can end up in rebalancing can be completely avoided. - Deferred reprogramming of the underlying clock event device. This optimizes for the situation where a hrtimer callback sets the need resched bit. In that case the code attempts to defer the re-programming of the clock event device up to the point where the scheduler has picked the next task and has the next hrtick timer armed. In case that there is no immediate reschedule or soft interrupts have to be handled before reaching the reschedule point in the interrupt entry code the clock event is reprogrammed in one of those code paths to prevent that the timer becomes stale. - Support for clocksource coupled clockevents The TSC deadline timer is coupled to the TSC. The next event is programmed in TSC time. Currently this is done by converting the CLOCK_MONOTONIC based expiry value into a relative timeout, converting it into TSC ticks, reading the TSC adding the delta ticks and writing the deadline MSR. As the timekeeping core has the conversion factors for the TSC already, the whole back and forth conversion can be completely avoided. The timekeeping core calculates the reverse conversion factors from nanoseconds to TSC ticks and utilizes the base timestamps of TSC and CLOCK_MONOTONIC which are updated once per tick. This allows a direct conversion into the TSC deadline value without reading the time and as a bonus keeps the deadline conversion in sync with the TSC conversion factors, which are updated by adjtimex() on systems with NTP/PTP enabled. - Allow inlining of the clocksource read and clockevent write functions when they are tiny enough, e.g. on x86 RDTSC and WRMSR. With all those enhancements in place a hrtick enabled scheduler provides the same performance as without hrtick. But also other hrtimer users obviously benefit from these optimizations. - Robustness improvements and cleanups of historical sins in the hrtimer and timekeeping code. - Rewrite of the clocksource watchdog. The clocksource watchdog code has over time reached the state of an impenetrable maze of duct tape and staples. The original design, which was made in the context of systems far smaller than today, is based on the assumption that the to be monitored clocksource (TSC) can be trivially compared against a known to be stable clocksource (HPET/ACPI-PM timer). Over the years this rather naive approach turned out to have major flaws. Long delays between the watchdog invocations can cause wrap arounds of the reference clocksource. The access to the reference clocksource degrades on large multi-sockets systems dure to interconnect congestion. This has been addressed with various heuristics which degraded the accuracy of the watchdog to the point that it fails to detect actual TSC problems on older hardware which exposes slow inter CPU drifts due to firmware manipulating the TSC to hide SMI time. The rewrite addresses this by: - Restricting the validation against the reference clocksource to the boot CPU which is usually closest to the legacy block which contains the reference clocksource (HPET/ACPI-PM). - Do a round robin validation betwen the boot CPU and the other CPUs based only on the TSC with an algorithm similar to the TSC synchronization code during CPU hotplug. - Being more leniant versus remote timeouts - The usual tiny fixes, cleanups and enhancements all over the place* tag 'timers-core-2026-04-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (75 commits) alarmtimer: Access timerqueue node under lock in suspend hrtimer: Fix incorrect #endif comment for BITS_PER_LONG check posix-timers: Fix stale function name in comment timers: Get this_cpu once while clearing the idle state clocksource: Rewrite watchdog code completely clocksource: Don't use non-continuous clocksources as watchdog x86/tsc: Handle CLOCK_SOURCE_VALID_FOR_HRES correctly MIPS: Don't select CLOCKSOURCE_WATCHDOG parisc: Remove unused clocksource flags hrtimer: Add a helper to retrieve a hrtimer from its timerqueue node hrtimer: Remove trailing comma after HRTIMER_MAX_CLOCK_BASES hrtimer: Mark index and clockid of clock base as const hrtimer: Drop unnecessary pointer indirection in hrtimer_expire_entry event hrtimer: Drop spurious space in 'enum hrtimer_base_type' hrtimer: Don't zero-initialize ret in hrtimer_nanosleep() hrtimer: Remove hrtimer_get_expires_ns() timekeeping: Mark offsets array as const timekeeping/auxclock: Consistently use raw timekeeper for tk_setup_internals() timer_list: Print offset as signed integer tracing: Use explicit array size instead of sentinel elements in symbol printing ... List of files: /linux/lib/timerqueue.c

1e4a70e0f64f8362653e81ad6a32c508b555dd23 - Merge branch 'sched/hrtick' into timers/core

Wed, 11 Mar 2026 20:14:32 +0000

Merge branch 'sched/hrtick' into timers/corePick up the hrtick related hrtimer changes so other unrelated changes canbe queued on top. List of files: /linux/lib/timerqueue.c

1339eeb73d6b99cf3aa9981f3f91d6ac4a49c72e - timerqueue: Provide linked timerqueue

Tue, 24 Feb 2026 16:38:52 +0000

timerqueue: Provide linked timerqueueThe hrtimer subsystem wants to peak ahead to the next and previous timer toevaluated whether a to be rearmed timer can stay at the same position inthe RB tree with the new expiry time.The linked RB tree provides the infrastructure for this as it maintainslinks to the previous and next nodes for each entry in the tree.Provide timerqueue wrappers around that.Signed-off-by: Thomas Gleixner Signed-off-by: Peter Zijlstra (Intel) Link: https://patch.msgid.link/20260224163431.734827095@kernel.org List of files: /linux/lib/timerqueue.c

d0034a7a4ac7fae708146ac0059b9c47a1543f0d - Merge branch 'next' into for-linus

Tue, 04 May 2021 18:46:00 +0000

Merge branch 'next' into for-linusPrepare input updates for 5.13 merge window. List of files: /linux/lib/timerqueue.c

b7f8f259896f669f131713b0c74ba4d008daa71d - Merge tag 'v5.12-rc7' into ecryptfs/next

Mon, 19 Apr 2021 04:39:17 +0000

Merge tag 'v5.12-rc7' into ecryptfs/nextRequired to pick up idmapped mount changes which changed some functionparameters. List of files: /linux/lib/timerqueue.c

5acac83bf2e42f51ab9fd315d657798754bf0bb8 - Merge tag 'v5.12-rc4' into next

Thu, 25 Mar 2021 18:46:10 +0000

Merge tag 'v5.12-rc4' into nextSync up with the mainline to bring in newest APIs. List of files: /linux/lib/timerqueue.c

f8bade6c9a6213c2c5ba6e5bf32415ecab6e41e5 - Merge drm/drm-next into drm-misc-next

Tue, 16 Mar 2021 08:06:23 +0000

Merge drm/drm-next into drm-misc-nextNoralf needs some patches in 5.12-rc3, and we've been delaying the 5.12merge due to the swap issue so it looks like a good time.Signed-off-by: Maxime Ripard List of files: /linux/lib/timerqueue.c

b470ebc9e0e57f53d1db9c49b8a3de4086babd05 - Merge tag 'irqchip-fixes-5.12-1' of git://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms into irq/urgent

Sun, 14 Mar 2021 15:34:35 +0000

Merge tag 'irqchip-fixes-5.12-1' of git://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms into irq/urgentPull irqchip fixes from Marc Zyngier: - More compatible strings for the Ingenic irqchip (introducing the JZ4760B SoC) - Select GENERIC_IRQ_MULTI_HANDLER on the ARM ep93xx platform - Drop all GENERIC_IRQ_MULTI_HANDLER selections from the irqchip Kconfig, now relying on the architecture to get it right - Drop the debugfs_file field from struct irq_domain, now that debugfs can track things on its own List of files: /linux/lib/timerqueue.c

35bb28ece90dfb7f72b77ba529f25f79323d9581 - Merge drm/drm-next into drm-intel-next

Thu, 11 Mar 2021 06:19:46 +0000

Merge drm/drm-next into drm-intel-nextSync up with upstream.Signed-off-by: Jani Nikula List of files: /linux/lib/timerqueue.c

4c9f4865f4604744d4f1a43db22ac6ec9dc8e587 - Merge branch 'fixes-rc2' into fixes

Mon, 08 Mar 2021 09:34:12 +0000

Merge branch 'fixes-rc2' into fixes List of files: /linux/lib/timerqueue.c

cdd38c5f1ce4398ec58fec95904b75824daab7b5 - Merge remote-tracking branch 'net/master'

Wed, 24 Feb 2021 12:36:58 +0000

Merge remote-tracking branch 'net/master' List of files: /linux/lib/timerqueue.c

72d6e4871f0457dc9e498f8437ea344ee6b78075 - Merge commit '3e10585335b7967326ca7b4118cada0d2d00a2ab' into v5.12/vfio/next

Mon, 22 Feb 2021 17:14:24 +0000

Merge commit '3e10585335b7967326ca7b4118cada0d2d00a2ab' into v5.12/vfio/nextUpdate to new follow_pte() definition List of files: /linux/lib/timerqueue.c

657bd90c93146a929c69cd43addf2804eb70c926 - Merge tag 'sched-core-2021-02-17' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Sun, 21 Feb 2021 20:35:04 +0000

Merge tag 'sched-core-2021-02-17' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tipPull scheduler updates from Ingo Molnar: "Core scheduler updates: - Add CONFIG_PREEMPT_DYNAMIC: this in its current form adds the preempt=none/voluntary/full boot options (default: full), to allow distros to build a PREEMPT kernel but fall back to close to PREEMPT_VOLUNTARY (or PREEMPT_NONE) runtime scheduling behavior via a boot time selection. There's also the /debug/sched_debug switch to do this runtime. This feature is implemented via runtime patching (a new variant of static calls). The scope of the runtime patching can be best reviewed by looking at the sched_dynamic_update() function in kernel/sched/core.c. ( Note that the dynamic none/voluntary mode isn't 100% identical, for example preempt-RCU is available in all cases, plus the preempt count is maintained in all models, which has runtime overhead even with the code patching. ) The PREEMPT_VOLUNTARY/PREEMPT_NONE models, used by the vast majority of distributions, are supposed to be unaffected. - Fix ignored rescheduling after rcu_eqs_enter(). This is a bug that was found via rcutorture triggering a hang. The bug is that rcu_idle_enter() may wake up a NOCB kthread, but this happens after the last generic need_resched() check. Some cpuidle drivers fix it by chance but many others don't. In true 2020 fashion the original bug fix has grown into a 5-patch scheduler/RCU fix series plus another 16 RCU patches to address the underlying issue of missed preemption events. These are the initial fixes that should fix current incarnations of the bug. - Clean up rbtree usage in the scheduler, by providing & using the following consistent set of rbtree APIs: partial-order; less() based: - rb_add(): add a new entry to the rbtree - rb_add_cached(): like rb_add(), but for a rb_root_cached total-order; cmp() based: - rb_find(): find an entry in an rbtree - rb_find_add(): find an entry, and add if not found - rb_find_first(): find the first (leftmost) matching entry - rb_next_match(): continue from rb_find_first() - rb_for_each(): iterate a sub-tree using the previous two - Improve the SMP/NUMA load-balancer: scan for an idle sibling in a single pass. This is a 4-commit series where each commit improves one aspect of the idle sibling scan logic. - Improve the cpufreq cooling driver by getting the effective CPU utilization metrics from the scheduler - Improve the fair scheduler's active load-balancing logic by reducing the number of active LB attempts & lengthen the load-balancing interval. This improves stress-ng mmapfork performance. - Fix CFS's estimated utilization (util_est) calculation bug that can result in too high utilization values Misc updates & fixes: - Fix the HRTICK reprogramming & optimization feature - Fix SCHED_SOFTIRQ raising race & warning in the CPU offlining code - Reduce dl_add_task_root_domain() overhead - Fix uprobes refcount bug - Process pending softirqs in flush_smp_call_function_from_idle() - Clean up task priority related defines, remove *USER_*PRIO and USER_PRIO() - Simplify the sched_init_numa() deduplication sort - Documentation updates - Fix EAS bug in update_misfit_status(), which degraded the quality of energy-balancing - Smaller cleanups"* tag 'sched-core-2021-02-17' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (51 commits) sched,x86: Allow !PREEMPT_DYNAMIC entry/kvm: Explicitly flush pending rcuog wakeup before last rescheduling point entry: Explicitly flush pending rcuog wakeup before last rescheduling point rcu/nocb: Trigger self-IPI on late deferred wake up before user resume rcu/nocb: Perform deferred wake up before last idle's need_resched() check rcu: Pull deferred rcuog wake up to rcu_eqs_enter() callers sched/features: Distinguish between NORMAL and DEADLINE hrtick sched/features: Fix hrtick reprogramming sched/deadline: Reduce rq lock contention in dl_add_task_root_domain() uprobes: (Re)add missing get_uprobe() in __find_uprobe() smp: Process pending softirqs in flush_smp_call_function_from_idle() sched: Harden PREEMPT_DYNAMIC static_call: Allow module use without exposing static_call_key sched: Add /debug/sched_preempt preempt/dynamic: Support dynamic preempt with preempt= boot option preempt/dynamic: Provide irqentry_exit_cond_resched() static call preempt/dynamic: Provide preempt_schedule[_notrace]() static calls preempt/dynamic: Provide cond_resched() and might_resched() static calls preempt: Introduce CONFIG_PREEMPT_DYNAMIC static_call: Provide DEFINE_STATIC_CALL_RET0() ... List of files: /linux/lib/timerqueue.c

798172b1374e28ecf687d6662fc5fdaec5c65385 - rbtree, timerqueue: Use rb_add_cached()

Wed, 29 Apr 2020 15:07:53 +0000

rbtree, timerqueue: Use rb_add_cached()Reduce rbtree boiler plate by using the new helpers.Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Acked-by: Davidlohr Bueso List of files: /linux/lib/timerqueue.c

976e3645923bdd2fe7893aae33fd7a21098bfb28 - Merge branch 'next' into for-linus

Mon, 25 Nov 2019 21:26:56 +0000

Merge branch 'next' into for-linusPrepare input updates for 5.5 merge window. List of files: /linux/lib/timerqueue.c

9f4813b531a0b8cc502fcfb142937fe4e9104d77 - Merge tag 'v5.4-rc8' into WIP.x86/mm, to pick up fixes

Tue, 19 Nov 2019 08:00:45 +0000

Merge tag 'v5.4-rc8' into WIP.x86/mm, to pick up fixesSigned-off-by: Ingo Molnar List of files: /linux/lib/timerqueue.c

ac94be498f84f7327533b62faca4c3da64434904 - Merge branch 'linus' into x86/hyperv

Fri, 15 Nov 2019 09:30:50 +0000

Merge branch 'linus' into x86/hypervPick up upstream fixes to avoid conflicts. List of files: /linux/lib/timerqueue.c

728d90bdc9e480dc93913e59a0aa3c896c7aa697 - Merge tag 'v5.4-rc5' into next

Sun, 27 Oct 2019 18:00:19 +0000

Merge tag 'v5.4-rc5' into nextSync up with mainline. List of files: /linux/lib/timerqueue.c

112d6212c80a1c560757520bd822a41c0ad15c2c - Merge tag 'v5.4-rc3' into spi-5.4

Fri, 18 Oct 2019 17:30:49 +0000

Merge tag 'v5.4-rc3' into spi-5.4Linux 5.4-rc3 List of files: /linux/lib/timerqueue.c