From 6f33b0bc4ea43f5c5ce7b7c9ab66051f80837862 Mon Sep 17 00:00:00 2001 From: Pavel Begunkov Date: Fri, 24 Sep 2021 21:59:44 +0100 Subject: [PATCH] io_uring: use slist for completion batching Currently we collect requests for completion batching in an array. Replace them with a singly linked list. It's as fast as arrays but doesn't take some much space in ctx, and will be used in future patches. Signed-off-by: Pavel Begunkov Link: https://lore.kernel.org/r/a666826f2854d17e9fb9417fb302edfeb750f425.1632516769.git.asml.silence@gmail.com Signed-off-by: Jens Axboe --- fs/io_uring.c | 52 +++++++++++++++++++++++++--------------------------- 1 file changed, 25 insertions(+), 27 deletions(-) diff --git a/fs/io_uring.c b/fs/io_uring.c index 27ca4fb..0ccfd70 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -322,8 +322,8 @@ struct io_submit_state { /* * Batch completion logic */ - struct io_kiocb *compl_reqs[IO_COMPL_BATCH]; - unsigned int compl_nr; + struct io_wq_work_list compl_reqs; + /* inline/task_work completion list, under ->uring_lock */ struct list_head free_list; }; @@ -882,6 +882,8 @@ struct io_kiocb { struct io_wq_work work; const struct cred *creds; + struct io_wq_work_node comp_list; + /* store used ubuf, so we can prevent reloading */ struct io_mapped_ubuf *imu; }; @@ -1168,7 +1170,7 @@ static inline void req_ref_get(struct io_kiocb *req) static inline void io_submit_flush_completions(struct io_ring_ctx *ctx) { - if (ctx->submit_state.compl_nr) + if (!wq_list_empty(&ctx->submit_state.compl_reqs)) __io_submit_flush_completions(ctx); } @@ -1325,6 +1327,7 @@ static struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p) INIT_LIST_HEAD(&ctx->submit_state.free_list); INIT_LIST_HEAD(&ctx->locked_free_list); INIT_DELAYED_WORK(&ctx->fallback_work, io_fallback_req_func); + INIT_WQ_LIST(&ctx->submit_state.compl_reqs); return ctx; err: kfree(ctx->dummy_ubuf); @@ -1826,11 +1829,16 @@ static inline bool io_req_needs_clean(struct io_kiocb *req) static void io_req_complete_state(struct io_kiocb *req, long res, unsigned int cflags) { + struct io_submit_state *state; + if (io_req_needs_clean(req)) io_clean_op(req); req->result = res; req->compl.cflags = cflags; req->flags |= REQ_F_COMPLETE_INLINE; + + state = &req->ctx->submit_state; + wq_list_add_tail(&req->comp_list, &state->compl_reqs); } static inline void __io_req_complete(struct io_kiocb *req, unsigned issue_flags, @@ -2319,13 +2327,14 @@ static void io_req_free_batch(struct req_batch *rb, struct io_kiocb *req, static void __io_submit_flush_completions(struct io_ring_ctx *ctx) __must_hold(&ctx->uring_lock) { + struct io_wq_work_node *node, *prev; struct io_submit_state *state = &ctx->submit_state; - int i, nr = state->compl_nr; struct req_batch rb; spin_lock(&ctx->completion_lock); - for (i = 0; i < nr; i++) { - struct io_kiocb *req = state->compl_reqs[i]; + wq_list_for_each(node, prev, &state->compl_reqs) { + struct io_kiocb *req = container_of(node, struct io_kiocb, + comp_list); __io_cqring_fill_event(ctx, req->user_data, req->result, req->compl.cflags); @@ -2335,15 +2344,18 @@ static void __io_submit_flush_completions(struct io_ring_ctx *ctx) io_cqring_ev_posted(ctx); io_init_req_batch(&rb); - for (i = 0; i < nr; i++) { - struct io_kiocb *req = state->compl_reqs[i]; + node = state->compl_reqs.first; + do { + struct io_kiocb *req = container_of(node, struct io_kiocb, + comp_list); + node = req->comp_list.next; if (req_ref_put_and_test(req)) io_req_free_batch(&rb, req, &ctx->submit_state); - } + } while (node); io_req_free_batch_finish(ctx, &rb); - state->compl_nr = 0; + INIT_WQ_LIST(&state->compl_reqs); } /* @@ -2668,17 +2680,10 @@ static void io_req_task_complete(struct io_kiocb *req, bool *locked) unsigned int cflags = io_put_rw_kbuf(req); long res = req->result; - if (*locked) { - struct io_ring_ctx *ctx = req->ctx; - struct io_submit_state *state = &ctx->submit_state; - + if (*locked) io_req_complete_state(req, res, cflags); - state->compl_reqs[state->compl_nr++] = req; - if (state->compl_nr == ARRAY_SIZE(state->compl_reqs)) - io_submit_flush_completions(ctx); - } else { + else io_req_complete_post(req, res, cflags); - } } static void __io_complete_rw(struct io_kiocb *req, long res, long res2, @@ -6962,15 +6967,8 @@ issue_sqe: * doesn't support non-blocking read/write attempts */ if (likely(!ret)) { - if (req->flags & REQ_F_COMPLETE_INLINE) { - struct io_ring_ctx *ctx = req->ctx; - struct io_submit_state *state = &ctx->submit_state; - - state->compl_reqs[state->compl_nr++] = req; - if (state->compl_nr == ARRAY_SIZE(state->compl_reqs)) - io_submit_flush_completions(ctx); + if (req->flags & REQ_F_COMPLETE_INLINE) return; - } linked_timeout = io_prep_linked_timeout(req); if (linked_timeout) -- 2.7.4