diff options
| author | Pavel Begunkov <asml.silence@gmail.com> | 2023-01-09 14:46:11 +0000 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2023-01-29 15:17:40 -0700 |
| commit | 130bd686d9be918e4cc8c03abf5794ba2d860502 (patch) | |
| tree | 7db8b4728da7507c82b246711843384ba3b3b0b9 /io_uring | |
| parent | 3181e22fb79910c7071e84a43af93ac89e8a7106 (diff) | |
io_uring: waitqueue-less cq waiting
With DEFER_TASKRUN only ctx->submitter_task might be waiting for CQEs,
we can use this to optimise io_cqring_wait(). Replace ->cq_wait
waitqueue with waking the task directly.
It works but misses an important optimisation covered by the following
patch, so this patch without follow ups might hurt performance.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/103d174d35d919d4cb0922d8a9c93a8f0c35f74a.1673274244.git.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 | 19 |
1 files changed, 12 insertions, 7 deletions
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c index f2e1dd076d98..be26829f7d20 100644 --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -1263,7 +1263,7 @@ static void io_req_local_work_add(struct io_kiocb *req) percpu_ref_put(&ctx->refs); return; } - /* need it for the following io_cqring_wake() */ + /* needed for the following wake up */ smp_mb__after_atomic(); if (unlikely(atomic_read(&req->task->io_uring->in_idle))) { @@ -1274,10 +1274,9 @@ static void io_req_local_work_add(struct io_kiocb *req) if (ctx->flags & IORING_SETUP_TASKRUN_FLAG) atomic_or(IORING_SQ_TASKRUN, &ctx->rings->sq_flags); - if (ctx->has_evfd) io_eventfd_signal(ctx); - __io_cqring_wake(ctx); + wake_up_state(ctx->submitter_task, TASK_INTERRUPTIBLE); percpu_ref_put(&ctx->refs); } @@ -2576,12 +2575,17 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events, do { unsigned long check_cq; - prepare_to_wait_exclusive(&ctx->cq_wait, &iowq.wq, - TASK_INTERRUPTIBLE); + if (ctx->flags & IORING_SETUP_DEFER_TASKRUN) { + set_current_state(TASK_INTERRUPTIBLE); + } else { + prepare_to_wait_exclusive(&ctx->cq_wait, &iowq.wq, + TASK_INTERRUPTIBLE); + } + ret = io_cqring_wait_schedule(ctx, &iowq); + __set_current_state(TASK_RUNNING); if (ret < 0) break; - __set_current_state(TASK_RUNNING); /* * Run task_work after scheduling and before io_should_wake(). * If we got woken because of task_work being processed, run it @@ -2609,7 +2613,8 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events, cond_resched(); } while (1); - finish_wait(&ctx->cq_wait, &iowq.wq); + if (!(ctx->flags & IORING_SETUP_DEFER_TASKRUN)) + finish_wait(&ctx->cq_wait, &iowq.wq); restore_saved_sigmask_unless(ret == -EINTR); return READ_ONCE(rings->cq.head) == READ_ONCE(rings->cq.tail) ? ret : 0; |