Kernel/linux-next
1
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git synced 2024-12-29 09:12:07 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

io_uring: optimize local tw add ctx pinning

Browse Source 
We currently pin the ctx for io_req_local_work_add() with
percpu_ref_get/put, which implies two rcu_read_lock/unlock pairs and some
extra overhead on top in the fast path. Replace it with a pure rcu read
and let io_ring_exit_work() synchronise against it.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/cbdfcb6b232627f30e9e50ef91f13c4f05910247.1680782017.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Pavel Begunkov 2023-04-06 14:20:08 +01:00 committed by Jens Axboe
parent ab1c590f5c
commit d73a572df2
1 changed files with 6 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
io_uring/io_uring.c
View File

@ -1332,9 +1332,9 @@ void __io_req_task_work_add(struct io_kiocb *req, bool allow_local)
struct io_ring_ctx *ctx = req->ctx;
if (allow_local && ctx->flags & IORING_SETUP_DEFER_TASKRUN) {
percpu_ref_get(&ctx->refs);
rcu_read_lock();
io_req_local_work_add(req);
percpu_ref_put(&ctx->refs);
rcu_read_unlock();
return;
}
@ -3052,6 +3052,10 @@ static __cold void io_ring_exit_work(struct work_struct *work)
spin_lock(&ctx->completion_lock);
spin_unlock(&ctx->completion_lock);
/* pairs with RCU read section in io_req_local_work_add() */
if (ctx->flags & IORING_SETUP_DEFER_TASKRUN)
synchronize_rcu();
io_ring_ctx_free(ctx);
}