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https://git.kernel.org/pub/scm/linux/kernel/git/herbert/cryptodev-2.6.git
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6c271ce2f1
This enables an application to do IO, without ever entering the kernel. By using the SQ ring to fill in new sqes and watching for completions on the CQ ring, we can submit and reap IOs without doing a single system call. The kernel side thread will poll for new submissions, and in case of HIPRI/polled IO, it'll also poll for completions. By default, we allow 1 second of active spinning. This can by changed by passing in a different grace period at io_uring_register(2) time. If the thread exceeds this idle time without having any work to do, it will set: sq_ring->flags |= IORING_SQ_NEED_WAKEUP. The application will have to call io_uring_enter() to start things back up again. If IO is kept busy, that will never be needed. Basically an application that has this feature enabled will guard it's io_uring_enter(2) call with: read_barrier(); if (*sq_ring->flags & IORING_SQ_NEED_WAKEUP) io_uring_enter(fd, 0, 0, IORING_ENTER_SQ_WAKEUP); instead of calling it unconditionally. It's mandatory to use fixed files with this feature. Failure to do so will result in the application getting an -EBADF CQ entry when submitting IO. Reviewed-by: Hannes Reinecke <hare@suse.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
135 lines
2.8 KiB
C
135 lines
2.8 KiB
C
/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
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/*
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* Header file for the io_uring interface.
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*
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* Copyright (C) 2019 Jens Axboe
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* Copyright (C) 2019 Christoph Hellwig
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*/
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#ifndef LINUX_IO_URING_H
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#define LINUX_IO_URING_H
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#include <linux/fs.h>
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#include <linux/types.h>
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/*
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* IO submission data structure (Submission Queue Entry)
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*/
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struct io_uring_sqe {
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__u8 opcode; /* type of operation for this sqe */
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__u8 flags; /* IOSQE_ flags */
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__u16 ioprio; /* ioprio for the request */
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__s32 fd; /* file descriptor to do IO on */
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__u64 off; /* offset into file */
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__u64 addr; /* pointer to buffer or iovecs */
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__u32 len; /* buffer size or number of iovecs */
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union {
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__kernel_rwf_t rw_flags;
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__u32 fsync_flags;
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};
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__u64 user_data; /* data to be passed back at completion time */
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union {
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__u16 buf_index; /* index into fixed buffers, if used */
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__u64 __pad2[3];
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};
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};
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/*
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* sqe->flags
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*/
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#define IOSQE_FIXED_FILE (1U << 0) /* use fixed fileset */
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/*
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* io_uring_setup() flags
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*/
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#define IORING_SETUP_IOPOLL (1U << 0) /* io_context is polled */
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#define IORING_SETUP_SQPOLL (1U << 1) /* SQ poll thread */
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#define IORING_SETUP_SQ_AFF (1U << 2) /* sq_thread_cpu is valid */
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#define IORING_OP_NOP 0
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#define IORING_OP_READV 1
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#define IORING_OP_WRITEV 2
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#define IORING_OP_FSYNC 3
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#define IORING_OP_READ_FIXED 4
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#define IORING_OP_WRITE_FIXED 5
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/*
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* sqe->fsync_flags
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*/
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#define IORING_FSYNC_DATASYNC (1U << 0)
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/*
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* IO completion data structure (Completion Queue Entry)
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*/
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struct io_uring_cqe {
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__u64 user_data; /* sqe->data submission passed back */
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__s32 res; /* result code for this event */
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__u32 flags;
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};
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/*
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* Magic offsets for the application to mmap the data it needs
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*/
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#define IORING_OFF_SQ_RING 0ULL
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#define IORING_OFF_CQ_RING 0x8000000ULL
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#define IORING_OFF_SQES 0x10000000ULL
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/*
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* Filled with the offset for mmap(2)
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*/
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struct io_sqring_offsets {
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__u32 head;
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__u32 tail;
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__u32 ring_mask;
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__u32 ring_entries;
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__u32 flags;
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__u32 dropped;
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__u32 array;
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__u32 resv1;
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__u64 resv2;
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};
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/*
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* sq_ring->flags
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*/
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#define IORING_SQ_NEED_WAKEUP (1U << 0) /* needs io_uring_enter wakeup */
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struct io_cqring_offsets {
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__u32 head;
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__u32 tail;
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__u32 ring_mask;
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__u32 ring_entries;
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__u32 overflow;
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__u32 cqes;
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__u64 resv[2];
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};
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/*
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* io_uring_enter(2) flags
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*/
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#define IORING_ENTER_GETEVENTS (1U << 0)
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#define IORING_ENTER_SQ_WAKEUP (1U << 1)
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/*
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* Passed in for io_uring_setup(2). Copied back with updated info on success
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*/
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struct io_uring_params {
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__u32 sq_entries;
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__u32 cq_entries;
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__u32 flags;
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__u32 sq_thread_cpu;
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__u32 sq_thread_idle;
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__u32 resv[5];
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struct io_sqring_offsets sq_off;
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struct io_cqring_offsets cq_off;
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};
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/*
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* io_uring_register(2) opcodes and arguments
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*/
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#define IORING_REGISTER_BUFFERS 0
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#define IORING_UNREGISTER_BUFFERS 1
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#define IORING_REGISTER_FILES 2
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#define IORING_UNREGISTER_FILES 3
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#endif
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