From: Jens Axboe <[email protected]>
To: Hao Xu <[email protected]>, [email protected]
Cc: Pavel Begunkov <[email protected]>
Subject: Re: [PATCH 4/4] io_uring: implement multishot mode for accept
Date: Mon, 9 May 2022 21:20:01 -0600 [thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <SG2PR01MB241129D7CDF5AFA14DB98946FFC79@SG2PR01MB2411.apcprd01.prod.exchangelabs.com>
On 5/8/22 9:32 AM, Hao Xu wrote:
> From: Hao Xu <[email protected]>
>
> Refactor io_accept() to support multishot mode.
>
> theoretical analysis:
> 1) when connections come in fast
> - singleshot:
> add accept sqe(userpsace) --> accept inline
userspace here too, like in the cover letter.
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index e0d12af04cd1..f21172913336 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -1146,6 +1146,7 @@ static const struct io_op_def io_op_defs[] = {
> .unbound_nonreg_file = 1,
> .pollin = 1,
> .poll_exclusive = 1,
> + .ioprio = 1, /* used for flags */
> },
> [IORING_OP_ASYNC_CANCEL] = {
> .audit_skip = 1,
> @@ -5706,6 +5707,7 @@ static int io_recv(struct io_kiocb *req, unsigned int issue_flags)
> static int io_accept_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
> {
> struct io_accept *accept = &req->accept;
> + unsigned flags;
>
> if (sqe->len || sqe->buf_index)
> return -EINVAL;
> @@ -5714,19 +5716,26 @@ static int io_accept_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
> accept->addr_len = u64_to_user_ptr(READ_ONCE(sqe->addr2));
> accept->flags = READ_ONCE(sqe->accept_flags);
> accept->nofile = rlimit(RLIMIT_NOFILE);
> + flags = READ_ONCE(sqe->ioprio);
> + if (flags & ~IORING_ACCEPT_MULTISHOT)
> + return -EINVAL;
>
> accept->file_slot = READ_ONCE(sqe->file_index);
> - if (accept->file_slot && (accept->flags & SOCK_CLOEXEC))
> + if (accept->file_slot && ((accept->flags & SOCK_CLOEXEC) ||
> + flags & IORING_ACCEPT_MULTISHOT))
> return -EINVAL;
So something ala:
if (accept_>file_slot) {
if (accept->flags & SOCK_CLOEXEC)
return -EINVAL;
if (flags & IORING_ACCEPT_MULTISHOT &&
accept->file_slot != IORING_FILE_INDEX_ALLOC)
return -EINVAL;
}
when rebased as mentioned in the cover reply.
if (accept->file_slot && (accept->flags & SOCK_CLOEXEC))
> static int io_accept(struct io_kiocb *req, unsigned int issue_flags)
> {
> + struct io_ring_ctx *ctx = req->ctx;
> struct io_accept *accept = &req->accept;
> bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK;
> unsigned int file_flags = force_nonblock ? O_NONBLOCK : 0;
> @@ -5734,6 +5743,7 @@ static int io_accept(struct io_kiocb *req, unsigned int issue_flags)
> struct file *file;
> int ret, fd;
>
> +retry:
> if (!fixed) {
> fd = __get_unused_fd_flags(accept->flags, accept->nofile);
> if (unlikely(fd < 0))
> @@ -5745,8 +5755,12 @@ static int io_accept(struct io_kiocb *req, unsigned int issue_flags)
> if (!fixed)
> put_unused_fd(fd);
> ret = PTR_ERR(file);
> - if (ret == -EAGAIN && force_nonblock)
> - return -EAGAIN;
> + if (ret == -EAGAIN && force_nonblock) {
> + if ((req->flags & IO_APOLL_MULTI_POLLED) ==
> + IO_APOLL_MULTI_POLLED)
> + ret = 0;
> + return ret;
> + }
Could probably do with a comment here for this check, it's not
immediately obvious unless you've already been deep in this part.
> @@ -5757,8 +5771,26 @@ static int io_accept(struct io_kiocb *req, unsigned int issue_flags)
> ret = io_install_fixed_file(req, file, issue_flags,
> accept->file_slot - 1);
> }
> - __io_req_complete(req, issue_flags, ret, 0);
> - return 0;
> +
> + if (!(req->flags & REQ_F_APOLL_MULTISHOT)) {
> + __io_req_complete(req, issue_flags, ret, 0);
> + return 0;
> + }
> + if (ret >= 0) {
> + bool filled;
> +
> + spin_lock(&ctx->completion_lock);
> + filled = io_fill_cqe_aux(ctx, req->cqe.user_data, ret,
> + IORING_CQE_F_MORE);
> + io_commit_cqring(ctx);
> + spin_unlock(&ctx->completion_lock);
> + if (!filled)
> + return -ECANCELED;
> + io_cqring_ev_posted(ctx);
> + goto retry;
> + }
> +
> + return ret;
> }
As mentioned, I still think this should be:
...
if (filled) {
io_cqring_ev_posted(ctx);
goto retry;
}
ret = -ECANCELED;
}
return ret;
--
Jens Axboe
next prev parent reply other threads:[~2022-05-10 3:20 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <[email protected]>
2022-05-08 15:32 ` [PATCH 1/4] io_uring: add IORING_ACCEPT_MULTISHOT for accept Hao Xu
2022-05-08 15:32 ` [PATCH 2/4] io_uring: add REQ_F_APOLL_MULTISHOT for requests Hao Xu
2022-05-08 15:32 ` [PATCH 3/4] io_uring: let fast poll support multishot Hao Xu
2022-05-10 3:20 ` Jens Axboe
2022-05-08 15:32 ` [PATCH 4/4] io_uring: implement multishot mode for accept Hao Xu
2022-05-10 3:20 ` Jens Axboe [this message]
2022-05-14 14:20 [PATCH v6 0/4] fast poll multishot mode Hao Xu
2022-05-14 14:20 ` [PATCH 4/4] io_uring: implement multishot mode for accept Hao Xu
[not found] <[email protected]>
2022-05-08 15:37 ` Hao Xu
[not found] <[email protected]>
2022-05-07 17:15 ` Hao Xu
-- strict thread matches above, loose matches on Subject: below --
2022-05-07 15:20 Hao Xu
2022-05-07 15:23 ` Jens Axboe
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