lwn.git/include/linux/hrtimer_defs.h, branch docs-next

hrtimer: Remove trailing comma after HRTIMER_MAX_CLOCK_BASES

2026-03-12T11:15:55+00:00

HRTIMER_MAX_CLOCK_BASES is required to stay the last value of the enum. Drop the trailing comma so no new members are added after it by mistake. Signed-off-by: Thomas Weißschuh (Schneider Electric) Signed-off-by: Thomas Gleixner Link: https://patch.msgid.link/20260311-hrtimer-cleanups-v1-11-095357392669@linutronix.de

hrtimer: Mark index and clockid of clock base as const

2026-03-12T11:15:55+00:00

These fields are initialized once and are never supposed to change. Mark them as const to make this explicit. Signed-off-by: Thomas Weißschuh (Schneider Electric) Signed-off-by: Thomas Gleixner Link: https://patch.msgid.link/20260311-hrtimer-cleanups-v1-10-095357392669@linutronix.de

hrtimer: Drop spurious space in 'enum hrtimer_base_type'

2026-03-12T11:15:55+00:00

This spurious space makes grepping for the enum definition annoying. Remove it. Signed-off-by: Thomas Weißschuh (Schneider Electric) Signed-off-by: Thomas Gleixner Link: https://patch.msgid.link/20260311-hrtimer-cleanups-v1-8-095357392669@linutronix.de

hrtimer: Use linked timerqueue

2026-02-27T15:40:16+00:00

To prepare for optimizing the rearming of enqueued timers, switch to the linked timerqueue. That allows to check whether the new expiry time changes the position of the timer in the RB tree or not, by checking the new expiry time against the previous and the next timers expiry. Signed-off-by: Thomas Gleixner Signed-off-by: Peter Zijlstra (Intel) Link: https://patch.msgid.link/20260224163431.806643179@kernel.org

hrtimer: Keep track of first expiring timer per clock base

2026-02-27T15:40:14+00:00

Evaluating the next expiry time of all clock bases is cache line expensive as the expiry time of the first expiring timer is not cached in the base and requires to access the timer itself, which is definitely in a different cache line. It's way more efficient to keep track of the expiry time on enqueue and dequeue operations as the relevant data is already in the cache at that point. Signed-off-by: Thomas Gleixner Signed-off-by: Peter Zijlstra (Intel) Link: https://patch.msgid.link/20260224163431.404839710@kernel.org

hrtimer: Avoid re-evaluation when nothing changed

2026-02-27T15:40:14+00:00

Most times there is no change between hrtimer_interrupt() deferring the rearm and the invocation of hrtimer_rearm_deferred(). In those cases it's a pointless exercise to re-evaluate the next expiring timer. Cache the required data and use it if nothing changed. Signed-off-by: Thomas Gleixner Signed-off-by: Peter Zijlstra (Intel) Link: https://patch.msgid.link/20260224163431.338569372@kernel.org

hrtimer: Rename hrtimer_cpu_base::in_hrtirq to deferred_rearm

2026-02-27T15:40:12+00:00

The upcoming deferred rearming scheme has the same effect as the deferred rearming when the hrtimer interrupt is executing. So it can reuse the in_hrtirq flag, but when it gets deferred beyond the hrtimer interrupt path, then the name does not make sense anymore. Rename it to deferred_rearm upfront to keep the actual functional change separate from the mechanical rename churn. Signed-off-by: Thomas Gleixner Signed-off-by: Peter Zijlstra (Intel) Link: https://patch.msgid.link/20260224163430.935623347@kernel.org

hrtimer: Replace the bitfield in hrtimer_cpu_base

2026-02-27T15:40:10+00:00

Use bool for the various flags as that creates better code in the hot path. Signed-off-by: Thomas Gleixner Signed-off-by: Peter Zijlstra (Intel) Link: https://patch.msgid.link/20260224163430.475262618@kernel.org

hrtimer: Remove public definition of HIGH_RES_NSEC

2026-01-13T10:05:48+00:00

This constant is only used in a single place and is has a very generic name polluting the global namespace. Move the constant closer to its only user. Signed-off-by: Thomas Weißschuh Signed-off-by: Thomas Gleixner Link: https://patch.msgid.link/20260107-hrtimer-header-cleanup-v1-2-1a698ef0ddae@linutronix.de

hrtimer: Remove unused resolution constants

2026-01-13T10:05:48+00:00

These constants are never used, remove them. Signed-off-by: Thomas Weißschuh Signed-off-by: Thomas Gleixner Link: https://patch.msgid.link/20260107-hrtimer-header-cleanup-v1-1-1a698ef0ddae@linutronix.de