diff options
| author | Pavel Begunkov <asml.silence@gmail.com> | 2026-02-15 22:06:52 +0000 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2026-02-15 15:12:54 -0700 |
| commit | 56112578c71213a10c995a56835bddb5e9ab1ed0 (patch) | |
| tree | acde906d76dc718862e9bd78e8275fe0823eb876 /io_uring | |
| parent | 6b34f8edf8b807b7f87901623aa52dfa1b29ef93 (diff) | |
io_uring: delay sqarray static branch disablement
io_key_has_sqarray static branch can be easily switched on/off by the
user every time patching the kernel. That can be very disruptive as it
might require heavy synchronisation across all CPUs. Use deferred static
keys, which can rate-limit it by deferring, batching and potentially
effectively eliminating dec+inc pairs.
Fixes: 9b296c625ac1d ("io_uring: static_key for !IORING_SETUP_NO_SQARRAY")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'io_uring')
| -rw-r--r-- | io_uring/io_uring.c | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c index c45af82dda3d..ccab8562d273 100644 --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -119,7 +119,7 @@ static void io_queue_sqe(struct io_kiocb *req, unsigned int extra_flags); static void __io_req_caches_free(struct io_ring_ctx *ctx); -static __read_mostly DEFINE_STATIC_KEY_FALSE(io_key_has_sqarray); +static __read_mostly DEFINE_STATIC_KEY_DEFERRED_FALSE(io_key_has_sqarray, HZ); struct kmem_cache *req_cachep; static struct workqueue_struct *iou_wq __ro_after_init; @@ -1978,7 +1978,7 @@ static bool io_get_sqe(struct io_ring_ctx *ctx, const struct io_uring_sqe **sqe) unsigned mask = ctx->sq_entries - 1; unsigned head = ctx->cached_sq_head++ & mask; - if (static_branch_unlikely(&io_key_has_sqarray) && + if (static_branch_unlikely(&io_key_has_sqarray.key) && (!(ctx->flags & IORING_SETUP_NO_SQARRAY))) { head = READ_ONCE(ctx->sq_array[head]); if (unlikely(head >= ctx->sq_entries)) { @@ -2173,7 +2173,7 @@ static __cold void io_ring_ctx_free(struct io_ring_ctx *ctx) io_rings_free(ctx); if (!(ctx->flags & IORING_SETUP_NO_SQARRAY)) - static_branch_dec(&io_key_has_sqarray); + static_branch_slow_dec_deferred(&io_key_has_sqarray); percpu_ref_exit(&ctx->refs); free_uid(ctx->user); @@ -2946,7 +2946,7 @@ static __cold int io_uring_create(struct io_ctx_config *config) ctx->clock_offset = 0; if (!(ctx->flags & IORING_SETUP_NO_SQARRAY)) - static_branch_inc(&io_key_has_sqarray); + static_branch_deferred_inc(&io_key_has_sqarray); if ((ctx->flags & IORING_SETUP_DEFER_TASKRUN) && !(ctx->flags & IORING_SETUP_IOPOLL)) |