io_uring: optimise plugging
Plugging is only needed with requests that also need a file, so hide
plugging under a ->needs_file check. Also, place ->needs_file and ->plug
bits into the same byte of io_op_defs, it may matter for compilers, e.g.
only with the change a tested one decided to optimise two memory testb
into a more with two register testb.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/1600d1287bb7d16451d4ef3343252787a5314927.1633532552.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 4494671..7759fab 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -894,12 +894,12 @@ struct io_defer_entry {
struct io_op_def {
/* needs req->file assigned */
unsigned needs_file : 1;
+ /* should block plug */
+ unsigned plug : 1;
/* hash wq insertion if file is a regular file */
unsigned hash_reg_file : 1;
/* unbound wq insertion if file is a non-regular file */
unsigned unbound_nonreg_file : 1;
- /* opcode is not supported by this kernel */
- unsigned not_supported : 1;
/* set if opcode supports polled "wait" */
unsigned pollin : 1;
unsigned pollout : 1;
@@ -907,8 +907,8 @@ struct io_op_def {
unsigned buffer_select : 1;
/* do prep async if is going to be punted */
unsigned needs_async_setup : 1;
- /* should block plug */
- unsigned plug : 1;
+ /* opcode is not supported by this kernel */
+ unsigned not_supported : 1;
/* size of async data needed, if any */
unsigned short async_size;
};
@@ -6978,7 +6978,6 @@ static int io_init_req(struct io_ring_ctx *ctx, struct io_kiocb *req,
const struct io_uring_sqe *sqe)
__must_hold(&ctx->uring_lock)
{
- struct io_submit_state *state;
unsigned int sqe_flags;
int personality;
@@ -7025,19 +7024,20 @@ static int io_init_req(struct io_ring_ctx *ctx, struct io_kiocb *req,
get_cred(req->creds);
req->flags |= REQ_F_CREDS;
}
- state = &ctx->submit_state;
-
- /*
- * Plug now if we have more than 1 IO left after this, and the target
- * is potentially a read/write to block based storage.
- */
- if (state->need_plug && io_op_defs[req->opcode].plug) {
- blk_start_plug(&state->plug);
- state->plug_started = true;
- state->need_plug = false;
- }
if (io_op_defs[req->opcode].needs_file) {
+ struct io_submit_state *state = &ctx->submit_state;
+
+ /*
+ * Plug now if we have more than 2 IO left after this, and the
+ * target is potentially a read/write to block based storage.
+ */
+ if (state->need_plug && io_op_defs[req->opcode].plug) {
+ state->plug_started = true;
+ state->need_plug = false;
+ blk_start_plug(&state->plug);
+ }
+
req->file = io_file_get(ctx, req, READ_ONCE(sqe->fd),
(sqe_flags & IOSQE_FIXED_FILE));
if (unlikely(!req->file))
