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io_uring: tweak iopoll CQE_SKIP event counting

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When iopolling the userspace specifies the minimum number of "events" it
expects. Previously, we had one CQE per request, so the definition of
an "event" was unequivocal, but that's not more the case anymore with
REQ_F_CQE_SKIP.

Currently it counts the number of completed requests, replace it with
the number of posted CQEs. This allows users of the "one CQE per link"
scheme to wait for all N links in a single syscall, which is not
possible without the patch and requires extra context switches.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/d5a965c4d2249827392037bbd0186f87fea49c55.1638714983.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Pavel Begunkov 2021-12-05 14:37:59 +00:00 • committed by Jens Axboe
parent d1fd1c201d
commit 83a13a4181
1 changed files with 3 additions and 3 deletions
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6
fs/io_uring.c
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@ -2538,10 +2538,10 @@ static int io_do_iopoll(struct io_ring_ctx *ctx, bool force_nonspin)
/* order with io_complete_rw_iopoll(), e.g. ->result updates */
if (!smp_load_acquire(&req->iopoll_completed))
break;
if (unlikely(req->flags & REQ_F_CQE_SKIP))
continue;
if (!(req->flags & REQ_F_CQE_SKIP))
__io_fill_cqe(ctx, req->user_data, req->result,
io_put_kbuf(req));
__io_fill_cqe(ctx, req->user_data, req->result, io_put_kbuf(req));
nr_events++;
}