From 6d63416dc57eb27a3d35e7b7526e9915479d7eff Mon Sep 17 00:00:00 2001 From: Pavel Begunkov Date: Wed, 6 Oct 2021 16:06:46 +0100 Subject: [PATCH] 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 Link: https://lore.kernel.org/r/1600d1287bb7d16451d4ef3343252787a5314927.1633532552.git.asml.silence@gmail.com Signed-off-by: Jens Axboe --- fs/io_uring.c | 32 ++++++++++++++++---------------- 1 file changed, 16 insertions(+), 16 deletions(-) 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)) -- 2.7.4