From 7cdaf587de7c6f494b8433fded19f7728e70e1ef Mon Sep 17 00:00:00 2001 From: Xiaoguang Wang Date: Wed, 10 Jun 2020 19:41:19 +0800 Subject: io_uring: avoid whole io_wq_work copy for requests completed inline If requests can be submitted and completed inline, we don't need to initialize whole io_wq_work in io_init_req(), which is an expensive operation, add a new 'REQ_F_WORK_INITIALIZED' to determine whether io_wq_work is initialized and add a helper io_req_init_async(), users must call io_req_init_async() for the first time touching any members of io_wq_work. I use /dev/nullb0 to evaluate performance improvement in my physical machine: modprobe null_blk nr_devices=1 completion_nsec=0 sudo taskset -c 60 fio -name=fiotest -filename=/dev/nullb0 -iodepth=128 -thread -rw=read -ioengine=io_uring -direct=1 -bs=4k -size=100G -numjobs=1 -time_based -runtime=120 before this patch: Run status group 0 (all jobs): READ: bw=724MiB/s (759MB/s), 724MiB/s-724MiB/s (759MB/s-759MB/s), io=84.8GiB (91.1GB), run=120001-120001msec With this patch: Run status group 0 (all jobs): READ: bw=761MiB/s (798MB/s), 761MiB/s-761MiB/s (798MB/s-798MB/s), io=89.2GiB (95.8GB), run=120001-120001msec About 5% improvement. Signed-off-by: Xiaoguang Wang Signed-off-by: Jens Axboe --- fs/io-wq.h | 5 ----- fs/io_uring.c | 40 ++++++++++++++++++++++++++++++++++++---- 2 files changed, 36 insertions(+), 9 deletions(-) (limited to 'fs') diff --git a/fs/io-wq.h b/fs/io-wq.h index 2db24d31fbc5..8e138fa88b9f 100644 --- a/fs/io-wq.h +++ b/fs/io-wq.h @@ -93,11 +93,6 @@ struct io_wq_work { pid_t task_pid; }; -#define INIT_IO_WORK(work) \ - do { \ - *(work) = (struct io_wq_work){}; \ - } while (0) \ - static inline struct io_wq_work *wq_next_work(struct io_wq_work *work) { if (!work->list.next) diff --git a/fs/io_uring.c b/fs/io_uring.c index ebea82e09963..5a2c004439f0 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -542,6 +542,7 @@ enum { REQ_F_BUFFER_SELECTED_BIT, REQ_F_NO_FILE_TABLE_BIT, REQ_F_QUEUE_TIMEOUT_BIT, + REQ_F_WORK_INITIALIZED_BIT, /* not a real bit, just to check we're not overflowing the space */ __REQ_F_LAST_BIT, @@ -599,6 +600,8 @@ enum { REQ_F_NO_FILE_TABLE = BIT(REQ_F_NO_FILE_TABLE_BIT), /* needs to queue linked timeout */ REQ_F_QUEUE_TIMEOUT = BIT(REQ_F_QUEUE_TIMEOUT_BIT), + /* io_wq_work is initialized */ + REQ_F_WORK_INITIALIZED = BIT(REQ_F_WORK_INITIALIZED_BIT), }; struct async_poll { @@ -911,6 +914,19 @@ EXPORT_SYMBOL(io_uring_get_socket); static void io_file_put_work(struct work_struct *work); +/* + * Note: must call io_req_init_async() for the first time you + * touch any members of io_wq_work. + */ +static inline void io_req_init_async(struct io_kiocb *req) +{ + if (req->flags & REQ_F_WORK_INITIALIZED) + return; + + memset(&req->work, 0, sizeof(req->work)); + req->flags |= REQ_F_WORK_INITIALIZED; +} + static inline bool io_async_submit(struct io_ring_ctx *ctx) { return ctx->flags & IORING_SETUP_SQPOLL; @@ -1037,6 +1053,9 @@ static inline void io_req_work_grab_env(struct io_kiocb *req, static inline void io_req_work_drop_env(struct io_kiocb *req) { + if (!(req->flags & REQ_F_WORK_INITIALIZED)) + return; + if (req->work.mm) { mmdrop(req->work.mm); req->work.mm = NULL; @@ -2785,8 +2804,14 @@ static int __io_splice_prep(struct io_kiocb *req, return ret; req->flags |= REQ_F_NEED_CLEANUP; - if (!S_ISREG(file_inode(sp->file_in)->i_mode)) + if (!S_ISREG(file_inode(sp->file_in)->i_mode)) { + /* + * Splice operation will be punted aync, and here need to + * modify io_wq_work.flags, so initialize io_wq_work firstly. + */ + io_req_init_async(req); req->work.flags |= IO_WQ_WORK_UNBOUND; + } return 0; } @@ -3372,8 +3397,10 @@ static int io_close_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) { /* * If we queue this for async, it must not be cancellable. That would - * leave the 'file' in an undeterminate state. + * leave the 'file' in an undeterminate state, and here need to modify + * io_wq_work.flags, so initialize io_wq_work firstly. */ + io_req_init_async(req); req->work.flags |= IO_WQ_WORK_NO_CANCEL; if (unlikely(req->ctx->flags & (IORING_SETUP_IOPOLL|IORING_SETUP_SQPOLL))) @@ -4851,6 +4878,8 @@ static int io_req_defer_prep(struct io_kiocb *req, if (!sqe) return 0; + io_req_init_async(req); + if (io_op_defs[req->opcode].file_table) { ret = io_grab_files(req); if (unlikely(ret)) @@ -5505,7 +5534,8 @@ static void __io_queue_sqe(struct io_kiocb *req, const struct io_uring_sqe *sqe) again: linked_timeout = io_prep_linked_timeout(req); - if (req->work.creds && req->work.creds != current_cred()) { + if ((req->flags & REQ_F_WORK_INITIALIZED) && req->work.creds && + req->work.creds != current_cred()) { if (old_creds) revert_creds(old_creds); if (old_creds == req->work.creds) @@ -5528,6 +5558,8 @@ again: goto exit; } punt: + io_req_init_async(req); + if (io_op_defs[req->opcode].file_table) { ret = io_grab_files(req); if (ret) @@ -5780,7 +5812,6 @@ static int io_init_req(struct io_ring_ctx *ctx, struct io_kiocb *req, refcount_set(&req->refs, 2); req->task = NULL; req->result = 0; - INIT_IO_WORK(&req->work); if (unlikely(req->opcode >= IORING_OP_LAST)) return -EINVAL; @@ -5802,6 +5833,7 @@ static int io_init_req(struct io_ring_ctx *ctx, struct io_kiocb *req, id = READ_ONCE(sqe->personality); if (id) { + io_req_init_async(req); req->work.creds = idr_find(&ctx->personality_idr, id); if (unlikely(!req->work.creds)) return -EINVAL; -- cgit v1.2.3