Aaron Wisner
4d042d3103
kernel: add configurable striped semaphore locking ...
Replace the system-wide semaphore spinlock with a configurable array
of naturally aligned lock stripes. Hash each semaphore by its natural
alignment without changing the semaphore object ABI.
Default CONFIG_SEM_LOCK_STRIPES to one so SMP and uniprocessor builds
preserve existing global-lock behavior and static memory use. Use a
scalar lock unless SMP striping is explicitly enabled, so UP builds
retain zero-sized spinlocks and avoid non-portable empty-struct arrays.
Require a power-of-two stripe count so the compiler reduces stripe
selection to a bitmask. Divide by the alignment of struct k_sem before
hashing to discard redundant address bits.
Do not impose cache-line alignment or padding. Explain how spinlock
and cache-line sizes affect the stripe count needed to reduce cache
contention.
Validate upstream semaphore regressions with zero-sized uniprocessor
spinlocks and SMP configurations using one, 16, and 32 stripes.
Reject non-power-of-two stripe counts at compile time.
An internal throughput microbenchmark on a quad-core ARM Cortex-A53
SMP system observed an improvement of approximately 3.1%.
Assisted-by: Codex:GPT-5
Signed-off-by: Aaron Wisner <awiz@openai.com>
2026-08-27 22:11:20 -04:00
kernel: userspace: Add z_waitq_head_locked()
2026-08-21 16:17:54 +02:00
kernel: mm: rename z_num_pagefaults_get to k_mem_num_*
2024-06-12 21:13:26 -04:00
kernel: Add private kernel header file kspinlock.h
2026-08-21 16:17:54 +02:00
kernel: thread_entry: fix include for TLS stack canaries
2026-08-19 18:41:05 -04:00
kernel: userspace: Add z_waitq_head_locked()
2026-08-21 16:17:54 +02:00
kernel: timer: Include include/zephyr/sys/clock.h
2026-07-30 07:45:05 -05:00
kernel: move the sleep API declarations to their own header
2026-08-20 08:52:31 +02:00
kernel: fix doxygen warnings exposed by adding kernel/ to docs INPUT
2026-07-01 17:05:28 -04:00
kernel: obj_core: register object types from a single init point
2026-07-01 23:45:35 -04:00
kernel: Update _sched_spinlock comment references
2026-08-21 16:17:54 +02:00
kernel: device: restrict the device_deinit syscall to driver objects
2026-08-10 09:14:56 -07:00
kernel: dynamic: fix kernel stack size overflow
2026-08-21 16:20:34 +02:00
kernel: dynamic: declare dynamic stubs when disabled
2023-07-24 12:59:43 -04:00
kernel: Update _sched_spinlock comment references
2026-08-21 16:17:54 +02:00
sys: printk: stop locking once a fatal error is being reported
2026-08-19 17:09:07 +01:00
build: namespace the generated headers with zephyr/
2024-05-28 22:03:55 +02:00
kernel: timeout: report the no-deadline case from the idle path
2026-08-12 19:27:28 -04:00
kernel: init: remove reference to legacy api
2026-08-26 18:14:02 -07:00
kernel: add closing comments to config endifs
2024-03-25 18:03:31 -04:00
kernel: add configurable striped semaphore locking
2026-08-27 22:11:20 -04:00
kernel: Kconfig.device: fix CONFIG_DEVICE_DEINIT_SUPPORT help text
2026-03-08 16:36:39 +01:00
kernel: Kconfig: remove prompts from SoC and Board Hooks
2026-08-27 21:26:07 +01:00
kernel: remove duplicate config OBJ_CORE_SEM
2026-07-27 11:45:01 -07:00
kernel: mmu: remove LINKER_GENERIC_SECTIONS_PRESENT_AT_BOOT
2026-06-23 09:11:08 -04:00
kernel: kheap: keep static heap init as a PRE_KERNEL_1 SYS_INIT
2026-07-06 19:42:44 -04:00
kernel: Fix race in mbox_message_dispose()
2026-08-18 20:22:32 -04:00
kernel: Switch main return type from void to int
2023-04-14 07:49:41 +09:00
kernel: kheap, mem_slab, mailbox: use kernel init hooks
2026-07-06 15:10:55 -04:00
kernel: k_free() no longer calls z_waitq_head()
2026-08-21 16:17:54 +02:00
sys: __assert: migrate users away from __ASSERT_ON
2026-08-27 12:12:11 +01:00
kernel: userspace: Add z_waitq_head_locked()
2026-08-21 16:17:54 +02:00
kernel: userspace: Add z_waitq_head_locked()
2026-08-21 16:17:54 +02:00
tracing: give k_sleep_ticks() its own trace point
2026-08-20 08:52:31 +02:00
kernel: obj_core: name the walk callback parameters
2026-08-17 10:26:20 +02:00
kernel: rename the reserved 'exit' labels to 'out'
2026-08-11 17:08:24 -04:00
kernel: poll: Remove redundant timeout check
2026-08-02 11:43:59 -04:00
kernel: priority queues: declare as static inlines
2024-04-22 16:40:11 -04:00
kernel: queue: skip blocking trace for no-wait get
2026-08-24 14:06:45 -07:00
kernel: userspace: Add z_waitq_head_locked()
2026-08-21 16:17:54 +02:00
kernel: Update _sched_spinlock comment references
2026-08-21 16:17:54 +02:00
kernel: add configurable striped semaphore locking
2026-08-27 22:11:20 -04:00
kernel: Add and use z_swap_locked()
2026-08-21 16:17:54 +02:00
kernel: spinlock: add z_assert_can_swap() for context-switch validation
2026-06-15 18:35:34 -04:00
kernel: stack: fix allocation size overflow
2026-08-22 19:20:09 -04:00
kernel: refactor sys_clock_hw_cycles_per_sec runtime support
2026-02-20 13:31:07 +01:00
kernel: system_work_q: register init via kernel init hook
2026-07-06 15:10:55 -04:00
kernel: Add and use z_reschedule_locked()
2026-08-21 16:17:54 +02:00
kernel: thread_monitor: reafactor and remove duplicate code
2025-04-04 07:42:20 +02:00
kernel: timeout: report the no-deadline case from the idle path
2026-08-12 19:27:28 -04:00
kernel: timeout: add bucketed delta-list backend
2026-07-09 18:02:12 -04:00
kernel: timeout: factor delta-list queue into a pluggable backend
2026-07-09 18:02:12 -04:00
kernel: timeout: add min-heap backend
2026-07-09 18:02:12 -04:00
kernel: timeout: add timer-wheel backend
2026-07-09 18:02:12 -04:00
kernel: userspace: Add z_waitq_head_locked()
2026-08-21 16:17:54 +02:00
kernel: Add private kernel header file kspinlock.h
2026-08-21 16:17:54 +02:00
kernel: usage: fix unused-variable warning when THREAD_USAGE_ALL=n
2026-08-19 17:12:24 +01:00
build: namespace the generated headers with zephyr/
2024-05-28 22:03:55 +02:00
toolchain: fix deprecation warning for iar
2026-08-12 13:11:27 -04:00
4d042d3103