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io_uring: fold evfd signalling under a slower path

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Add ->has_evfd flag, which is true IFF there is an eventfd attached, and
use it to hide io_eventfd_signal() into __io_commit_cqring_flush() and
combine fast checks in a single if. Also, gcc 11.2 wasn't inlining
io_cqring_ev_posted() without this change, so helps with that as well.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/f6168471997decded475a063f92915787975a30b.1647481208.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Pavel Begunkov 2022-03-17 02:03:42 +00:00 committed by Jens Axboe
parent 9333f6b462
commit 9aa8dfde48
1 changed files with 34 additions and 26 deletions
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60
fs/io_uring.c
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@ -347,6 +347,7 @@ struct io_ring_ctx {
unsigned int off_timeout_used: 1;
unsigned int drain_active: 1;
unsigned int drain_disabled: 1;
unsigned int has_evfd: 1;
} ____cacheline_aligned_in_smp;
/* submission data */
@ -1181,6 +1182,7 @@ static int io_install_fixed_file(struct io_kiocb *req, struct file *file,
static int io_close_fixed(struct io_kiocb *req, unsigned int issue_flags);
static enum hrtimer_restart io_link_timeout_fn(struct hrtimer *timer);
static void io_eventfd_signal(struct io_ring_ctx *ctx);
static struct kmem_cache *req_cachep;
@ -1785,15 +1787,19 @@ static inline void io_commit_cqring(struct io_ring_ctx *ctx)
smp_store_release(&ctx->rings->cq.tail, ctx->cached_cq_tail);
}
static __cold void __io_commit_cqring_flush(struct io_ring_ctx *ctx)
static void __io_commit_cqring_flush(struct io_ring_ctx *ctx)
{
spin_lock(&ctx->completion_lock);
if (ctx->off_timeout_used)
io_flush_timeouts(ctx);
if (ctx->drain_active)
io_queue_deferred(ctx);
io_commit_cqring(ctx);
spin_unlock(&ctx->completion_lock);
if (ctx->off_timeout_used || ctx->drain_active) {
spin_lock(&ctx->completion_lock);
if (ctx->off_timeout_used)
io_flush_timeouts(ctx);
if (ctx->drain_active)
io_queue_deferred(ctx);
io_commit_cqring(ctx);
spin_unlock(&ctx->completion_lock);
}
if (ctx->has_evfd)
io_eventfd_signal(ctx);
}
static inline bool io_sqring_full(struct io_ring_ctx *ctx)
@ -1852,6 +1858,17 @@ out:
rcu_read_unlock();
}
static inline void io_cqring_wake(struct io_ring_ctx *ctx)
{
/*
* wake_up_all() may seem excessive, but io_wake_function() and
* io_should_wake() handle the termination of the loop and only
* wake as many waiters as we need to.
*/
if (wq_has_sleeper(&ctx->cq_wait))
wake_up_all(&ctx->cq_wait);
}
/*
* This should only get called when at least one event has been posted.
* Some applications rely on the eventfd notification count only changing
@ -1861,31 +1878,21 @@ out:
*/
static inline void io_cqring_ev_posted(struct io_ring_ctx *ctx)
{
if (unlikely(ctx->off_timeout_used || ctx->drain_active))
if (unlikely(ctx->off_timeout_used || ctx->drain_active ||
ctx->has_evfd))
__io_commit_cqring_flush(ctx);
/*
* wake_up_all() may seem excessive, but io_wake_function() and
* io_should_wake() handle the termination of the loop and only
* wake as many waiters as we need to.
*/
if (wq_has_sleeper(&ctx->cq_wait))
wake_up_all(&ctx->cq_wait);
if (unlikely(rcu_dereference_raw(ctx->io_ev_fd)))
io_eventfd_signal(ctx);
io_cqring_wake(ctx);
}
static void io_cqring_ev_posted_iopoll(struct io_ring_ctx *ctx)
{
if (unlikely(ctx->off_timeout_used || ctx->drain_active))
if (unlikely(ctx->off_timeout_used || ctx->drain_active ||
ctx->has_evfd))
__io_commit_cqring_flush(ctx);
if (ctx->flags & IORING_SETUP_SQPOLL) {
if (wq_has_sleeper(&ctx->cq_wait))
wake_up_all(&ctx->cq_wait);
}
if (unlikely(rcu_dereference_raw(ctx->io_ev_fd)))
io_eventfd_signal(ctx);
if (ctx->flags & IORING_SETUP_SQPOLL)
io_cqring_wake(ctx);
}
/* Returns true if there are no backlogged entries after the flush */
@ -9898,7 +9905,7 @@ static int io_eventfd_register(struct io_ring_ctx *ctx, void __user *arg,
return ret;
}
ev_fd->eventfd_async = eventfd_async;
ctx->has_evfd = true;
rcu_assign_pointer(ctx->io_ev_fd, ev_fd);
return 0;
}
@ -9918,6 +9925,7 @@ static int io_eventfd_unregister(struct io_ring_ctx *ctx)
ev_fd = rcu_dereference_protected(ctx->io_ev_fd,
lockdep_is_held(&ctx->uring_lock));
if (ev_fd) {
ctx->has_evfd = false;
rcu_assign_pointer(ctx->io_ev_fd, NULL);
call_rcu(&ev_fd->rcu, io_eventfd_put);
return 0;