diff options
| author | Eric Dumazet <edumazet@google.com> | 2025-03-08 17:48:36 +0100 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2025-03-13 12:07:17 +0100 |
| commit | feb864ee99a2d8a22800342388401f3a3b90d42b (patch) | |
| tree | 0995392e76f26df837664c08ca51cc940b9b0cac /include/linux/sched/signal.h | |
| parent | 538d710ec74233f99dc0fd604d45a2b6143c8e2c (diff) | |
posix-timers: Make signal_struct:: Next_posix_timer_id an atomic_t
The global hash_lock protecting the posix timer hash table can be heavily
contended especially when there is an extensive linear search for a timer
ID.
Timer IDs are handed out by monotonically increasing next_posix_timer_id
and then validating that there is no timer with the same ID in the hash
table. Both operations happen with the global hash lock held.
To reduce the hash lock contention the hash will be reworked to a scaled
hash with per bucket locks, which requires to handle the ID counter
lockless.
Prepare for this by making next_posix_timer_id an atomic_t, which can be
used lockless with atomic_inc_return().
[ tglx: Adopted from Eric's series, massaged change log and simplified it ]
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/all/20250219125522.2535263-2-edumazet@google.com
Link: https://lore.kernel.org/all/20250308155624.151545978@linutronix.de
Diffstat (limited to 'include/linux/sched/signal.h')
| -rw-r--r-- | include/linux/sched/signal.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h index d5d03d919df8..72649d7fce2a 100644 --- a/include/linux/sched/signal.h +++ b/include/linux/sched/signal.h @@ -136,7 +136,7 @@ struct signal_struct { #ifdef CONFIG_POSIX_TIMERS /* POSIX.1b Interval Timers */ - unsigned int next_posix_timer_id; + atomic_t next_posix_timer_id; struct hlist_head posix_timers; struct hlist_head ignored_posix_timers; |