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authorPavel Begunkov <asml.silence@gmail.com>2023-04-06 14:20:14 +0100
committerJens Axboe <axboe@kernel.dk>2023-04-06 16:24:36 -0600
commit360cd42c4e95ff06d8d7b0a54e42236c7e7c187f (patch)
tree97807acf0f2bcb3ada1ad005bbaa8d95396aceab /io_uring
parentc66ae3ec38f946edb1776d25c1c8cd63803b8ec3 (diff)
io_uring: optimise io_req_local_work_add
Chains of memory accesses are never good for performance. The req->task->io_uring->in_cancel in io_req_local_work_add() is there so that when a task is exiting via io_uring_try_cancel_requests() and starts waiting for completions, it gets woken up by every new task_work item queued. Do a little trick by announcing waiting in io_uring_try_cancel_requests(), making io_req_local_work_add() wake us up. We also need to check for deferred tw items after prepare_to_wait(TASK_INTERRUPTIBLE); Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/fb11597e9bbcb365901824f8c5c2cf0d6ee100d0.1680782017.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.c24
1 files changed, 16 insertions, 8 deletions
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 0ea50c46f27f..9bbf58297a0e 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -1335,10 +1335,6 @@ static void io_req_local_work_add(struct io_kiocb *req, unsigned flags)
&req->io_task_work.node));
if (!first) {
- if (unlikely(atomic_read(&req->task->io_uring->in_cancel))) {
- io_move_task_work_from_local(ctx);
- return;
- }
if (ctx->flags & IORING_SETUP_TASKRUN_FLAG)
atomic_or(IORING_SQ_TASKRUN, &ctx->rings->sq_flags);
if (ctx->has_evfd)
@@ -3205,6 +3201,12 @@ static __cold bool io_uring_try_cancel_requests(struct io_ring_ctx *ctx,
enum io_wq_cancel cret;
bool ret = false;
+ /* set it so io_req_local_work_add() would wake us up */
+ if (ctx->flags & IORING_SETUP_DEFER_TASKRUN) {
+ atomic_set(&ctx->cq_wait_nr, 1);
+ smp_mb();
+ }
+
/* failed during ring init, it couldn't have issued any requests */
if (!ctx->rings)
return false;
@@ -3259,6 +3261,8 @@ __cold void io_uring_cancel_generic(bool cancel_all, struct io_sq_data *sqd)
{
struct io_uring_task *tctx = current->io_uring;
struct io_ring_ctx *ctx;
+ struct io_tctx_node *node;
+ unsigned long index;
s64 inflight;
DEFINE_WAIT(wait);
@@ -3280,9 +3284,6 @@ __cold void io_uring_cancel_generic(bool cancel_all, struct io_sq_data *sqd)
break;
if (!sqd) {
- struct io_tctx_node *node;
- unsigned long index;
-
xa_for_each(&tctx->xa, index, node) {
/* sqpoll task will cancel all its requests */
if (node->ctx->sq_data)
@@ -3305,7 +3306,13 @@ __cold void io_uring_cancel_generic(bool cancel_all, struct io_sq_data *sqd)
prepare_to_wait(&tctx->wait, &wait, TASK_INTERRUPTIBLE);
io_run_task_work();
io_uring_drop_tctx_refs(current);
-
+ xa_for_each(&tctx->xa, index, node) {
+ if (!llist_empty(&node->ctx->work_llist)) {
+ WARN_ON_ONCE(node->ctx->submitter_task &&
+ node->ctx->submitter_task != current);
+ goto end_wait;
+ }
+ }
/*
* If we've seen completions, retry without waiting. This
* avoids a race where a completion comes in before we did
@@ -3313,6 +3320,7 @@ __cold void io_uring_cancel_generic(bool cancel_all, struct io_sq_data *sqd)
*/
if (inflight == tctx_inflight(tctx, !cancel_all))
schedule();
+end_wait:
finish_wait(&tctx->wait, &wait);
} while (1);