linux.git/include/linux/hrtimer_types.h, branch v7.1 Linux kernel source tree hrtimer: Use linked timerqueue 2026-02-27T15:40:16+00:00 Thomas Gleixner tglx@kernel.org 2026-02-24T16:38:57+00:00 b7418e6e9b87b849af4df93d527ff83498d1e4c3 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 <tglx@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://patch.msgid.link/20260224163431.806643179@kernel.org 
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 <tglx@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260224163431.806643179@kernel.org
hrtimer: Convert state and properties to boolean 2026-02-27T15:40:11+00:00 Thomas Gleixner tglx@kernel.org 2026-02-24T16:37:23+00:00 22f011be7aaa77ca8f502b9dd07b7334f9965d18 All 'u8' flags are true booleans, so make it entirely clear that these can only contain true or false. This is especially true for hrtimer::state, which has a historical leftover of using the state with bitwise operations. That was used in the early hrtimer implementation with several bits, but then converted to a boolean state. But that conversion missed to replace the bit OR and bit check operations all over the place, which creates suboptimal code. As of today 'state' is a misnomer because it's only purpose is to reflect whether the timer is enqueued into the RB-tree or not. Rename it to 'is_queued' and make all operations on it boolean. This reduces text size from 8926 to 8732 bytes. Signed-off-by: Thomas Gleixner <tglx@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://patch.msgid.link/20260224163430.542427240@kernel.org 
All 'u8' flags are true booleans, so make it entirely clear that these can
only contain true or false.

This is especially true for hrtimer::state, which has a historical leftover
of using the state with bitwise operations. That was used in the early
hrtimer implementation with several bits, but then converted to a boolean
state. But that conversion missed to replace the bit OR and bit check
operations all over the place, which creates suboptimal code. As of today
'state' is a misnomer because it's only purpose is to reflect whether the
timer is enqueued into the RB-tree or not. Rename it to 'is_queued' and
make all operations on it boolean.

This reduces text size from 8926 to 8732 bytes.

Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260224163430.542427240@kernel.org
hrtimer: Provide LAZY_REARM mode 2026-02-27T15:40:06+00:00 Peter Zijlstra peterz@infradead.org 2026-02-24T16:36:01+00:00 b7dd64778aa3f89de9afa1e81171cfe110ddc525 The hrtick timer is frequently rearmed before expiry and most of the time the new expiry is past the armed one. As this happens on every context switch it becomes expensive with scheduling heavy work loads especially in virtual machines as the "hardware" reprogamming implies a VM exit. Add a lazy rearm mode flag which skips the reprogamming if: 1) The timer was the first expiring timer before the rearm 2) The new expiry time is farther out than the armed time This avoids a massive amount of reprogramming operations of the hrtick timer for the price of eventually taking the alredy armed interrupt for nothing. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://patch.msgid.link/20260224163429.408524456@kernel.org 
The hrtick timer is frequently rearmed before expiry and most of the time
the new expiry is past the armed one. As this happens on every context
switch it becomes expensive with scheduling heavy work loads especially in
virtual machines as the "hardware" reprogamming implies a VM exit.

Add a lazy rearm mode flag which skips the reprogamming if:

    1) The timer was the first expiring timer before the rearm

    2) The new expiry time is farther out than the armed time

This avoids a massive amount of reprogramming operations of the hrtick
timer for the price of eventually taking the alredy armed interrupt for
nothing.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260224163429.408524456@kernel.org
hrtimers: Make callback function pointer private 2025-04-05T08:30:17+00:00 Nam Cao namcao@linutronix.de 2025-02-05T10:55:16+00:00 04257da0c99c9d4ff7c5bb93046482e1f7d34938 Make the struct hrtimer::function field private, to prevent users from changing this field in an unsafe way. hrtimer_update_function() should be used if the callback function needs to be changed. Signed-off-by: Nam Cao <namcao@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/all/7d0e6e0c5c59a64a9bea940051aac05d750bc0c2.1738746927.git.namcao@linutronix.de 
Make the struct hrtimer::function field private, to prevent users from
changing this field in an unsafe way. hrtimer_update_function() should be
used if the callback function needs to be changed.

Signed-off-by: Nam Cao <namcao@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/all/7d0e6e0c5c59a64a9bea940051aac05d750bc0c2.1738746927.git.namcao@linutronix.de
hrtimers: Delete hrtimer_init() 2025-04-05T08:30:17+00:00 Nam Cao namcao@linutronix.de 2025-02-05T10:55:10+00:00 9779489a31d77a7b9cb6f20d2d2caced4e29dbe6 hrtimer_init() is now unused. Delete it. Signed-off-by: Nam Cao <namcao@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/all/003722f60c7a2a4f8d4ed24fb741aa313b7e5136.1738746927.git.namcao@linutronix.de 
hrtimer_init() is now unused. Delete it.

Signed-off-by: Nam Cao <namcao@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/all/003722f60c7a2a4f8d4ed24fb741aa313b7e5136.1738746927.git.namcao@linutronix.de
timerqueue: Split out timerqueue_types.h 2023-12-21T00:26:31+00:00 Kent Overstreet kent.overstreet@linux.dev 2023-12-11T18:32:55+00:00 eee51b0ae5c52a77ed65ad59b55002d1397b40d5 Trimming down sched.h dependencies: timerqueue_types can include just rbtree_types.h instead of pulling in rbtree.h. Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev> 
Trimming down sched.h dependencies: timerqueue_types can include just
rbtree_types.h instead of pulling in rbtree.h.

Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
hrtimers: Split out hrtimer_types.h 2023-12-21T00:26:30+00:00 Kent Overstreet kent.overstreet@linux.dev 2023-12-11T16:52:02+00:00 50d91c76582513852e38eb80491f54d44cfb51fc We need to reduce the scope of what's included in sched.h: task_struct includes a hrtimer, so split out the core types into their own header. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev> Cc: Thomas Gleixner <tglx@linutronix.de> 
We need to reduce the scope of what's included in sched.h: task_struct
includes a hrtimer, so split out the core types into their own header.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Thomas Gleixner <tglx@linutronix.de>