io_uring: don't batch task put on reqs free

We're trying to batch io_put_task() in io_free_batch_list(), but
considering that the hot path is a simple inc, it's most cerainly and
probably faster to just do io_put_task() instead of task tracking.

We don't care about io_put_task_remote() as it's only for IOPOLL
where polling/waiting is done by not the submitter task.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/4a7ef7dce845fe2bd35507bf389d6bd2d5c1edf0.1687518903.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 4d86139..3eec5c7 100644 (file)
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -754,29 +754,29 @@ static void io_cqring_overflow_flush(struct io_ring_ctx *ctx)
 }
 
 /* can be called by any task */
-static void io_put_task_remote(struct task_struct *task, int nr)
+static void io_put_task_remote(struct task_struct *task)
 {
        struct io_uring_task *tctx = task->io_uring;
 
-       percpu_counter_sub(&tctx->inflight, nr);
+       percpu_counter_sub(&tctx->inflight, 1);
        if (unlikely(atomic_read(&tctx->in_cancel)))
                wake_up(&tctx->wait);
-       put_task_struct_many(task, nr);
+       put_task_struct(task);
 }
 
 /* used by a task to put its own references */
-static void io_put_task_local(struct task_struct *task, int nr)
+static void io_put_task_local(struct task_struct *task)
 {
-       task->io_uring->cached_refs += nr;
+       task->io_uring->cached_refs++;
 }
 
 /* must to be called somewhat shortly after putting a request */
-static inline void io_put_task(struct task_struct *task, int nr)
+static inline void io_put_task(struct task_struct *task)
 {
        if (likely(task == current))
-               io_put_task_local(task, nr);
+               io_put_task_local(task);
        else
-               io_put_task_remote(task, nr);
+               io_put_task_remote(task);
 }
 
 void io_task_refs_refill(struct io_uring_task *tctx)
@@ -1033,7 +1033,7 @@ static void __io_req_complete_post(struct io_kiocb *req, unsigned issue_flags)
                 * we don't hold ->completion_lock. Clean them here to avoid
                 * deadlocks.
                 */
-               io_put_task_remote(req->task, 1);
+               io_put_task_remote(req->task);
                wq_list_add_head(&req->comp_list, &ctx->locked_free_list);
                ctx->locked_free_nr++;
        }
@@ -1518,9 +1518,6 @@ void io_queue_next(struct io_kiocb *req)
 void io_free_batch_list(struct io_ring_ctx *ctx, struct io_wq_work_node *node)
        __must_hold(&ctx->uring_lock)
 {
-       struct task_struct *task = NULL;
-       int task_refs = 0;
-
        do {
                struct io_kiocb *req = container_of(node, struct io_kiocb,
                                                    comp_list);
@@ -1550,19 +1547,10 @@ void io_free_batch_list(struct io_ring_ctx *ctx, struct io_wq_work_node *node)
 
                io_req_put_rsrc_locked(req, ctx);
 
-               if (req->task != task) {
-                       if (task)
-                               io_put_task(task, task_refs);
-                       task = req->task;
-                       task_refs = 0;
-               }
-               task_refs++;
+               io_put_task(req->task);
                node = req->comp_list.next;
                io_req_add_to_cache(req, ctx);
        } while (node);
-
-       if (task)
-               io_put_task(task, task_refs);
 }
 
 static void __io_submit_flush_completions(struct io_ring_ctx *ctx)