io_uring: flag SQPOLL busy condition to userspace

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Now that we have backpressure, for SQPOLL, we have one more condition
that warrants flagging that the application needs to enter the kernel:
we failed to submit IO due to backpressure. Make sure we catch that
and flag it appropriately.

If we run into backpressure issues with the SQPOLL thread, flag it
as such to the application by setting IORING_SQ_NEED_WAKEUP. This will
cause the application to enter the kernel, and that will flush the
backlog and clear the condition.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

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This commit is contained in:

Jens Axboe 2019-11-10 16:56:04 -07:00

parent 47f467686e

commit c1edbf5f08

1 changed files with 16 additions and 6 deletions

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fs/io_uring.c

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