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io_uring: optimise out unlikely link queue

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__io_queue_sqe() tries to issue as much requests of a link as it can,
and uses io_put_req_find_next() to extract a next one, targeting inline
completed requests. As now __io_queue_sqe() is always used together with
struct io_comp_state, it leaves next propagation only a small window and
only for async reqs, that doesn't justify its existence.

Remove it, make __io_queue_sqe() to issue only a head request. It
simplifies the code and will allow other optimisations.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Pavel Begunkov 2021-02-12 03:23:51 +00:00 committed by Jens Axboe
parent bd75904590
commit d3d7298d05
1 changed files with 10 additions and 32 deletions
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42
fs/io_uring.c
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@ -6563,26 +6563,20 @@ static struct io_kiocb *io_prep_linked_timeout(struct io_kiocb *req)
static void __io_queue_sqe(struct io_kiocb *req)
{
struct io_kiocb *linked_timeout;
struct io_kiocb *linked_timeout = io_prep_linked_timeout(req);
const struct cred *old_creds = NULL;
int ret;
again:
linked_timeout = io_prep_linked_timeout(req);
if ((req->flags & REQ_F_WORK_INITIALIZED) &&
(req->work.flags & IO_WQ_WORK_CREDS) &&
req->work.identity->creds != current_cred()) {
if (old_creds)
revert_creds(old_creds);
if (old_creds == req->work.identity->creds)
old_creds = NULL; /* restored original creds */
else
old_creds = override_creds(req->work.identity->creds);
}
req->work.identity->creds != current_cred())
old_creds = override_creds(req->work.identity->creds);
ret = io_issue_sqe(req, IO_URING_F_NONBLOCK|IO_URING_F_COMPLETE_DEFER);
if (old_creds)
revert_creds(old_creds);
/*
* We async punt it if the file wasn't marked NOWAIT, or if the file
* doesn't support non-blocking read/write attempts
@ -6595,9 +6589,6 @@ static void __io_queue_sqe(struct io_kiocb *req)
*/
io_queue_async_work(req);
}
if (linked_timeout)
io_queue_linked_timeout(linked_timeout);
} else if (likely(!ret)) {
/* drop submission reference */
if (req->flags & REQ_F_COMPLETE_INLINE) {
@ -6605,31 +6596,18 @@ static void __io_queue_sqe(struct io_kiocb *req)
struct io_comp_state *cs = &ctx->submit_state.comp;
cs->reqs[cs->nr++] = req;
if (cs->nr == IO_COMPL_BATCH)
if (cs->nr == ARRAY_SIZE(cs->reqs))
io_submit_flush_completions(cs, ctx);
req = NULL;
} else {
req = io_put_req_find_next(req);
}
if (linked_timeout)
io_queue_linked_timeout(linked_timeout);
if (req) {
if (!(req->flags & REQ_F_FORCE_ASYNC))
goto again;
io_queue_async_work(req);
io_put_req(req);
}
} else {
/* un-prep timeout, so it'll be killed as any other linked */
req->flags &= ~REQ_F_LINK_TIMEOUT;
req_set_fail_links(req);
io_put_req(req);
io_req_complete(req, ret);
}
if (old_creds)
revert_creds(old_creds);
if (linked_timeout)
io_queue_linked_timeout(linked_timeout);
}
static void io_queue_sqe(struct io_kiocb *req, const struct io_uring_sqe *sqe)