io_uring: don't submit sqes when ctx->refs is dying

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When IORING_SETUP_SQPOLL is enabled, io_ring_ctx_wait_and_kill() will wait
for sq thread to idle by busy loop:

    while (ctx->sqo_thread && !wq_has_sleeper(&ctx->sqo_wait))
        cond_resched();

Above loop isn't very CPU friendly, it may introduce a short cpu burst on
the current cpu.

If ctx->refs is dying, we forbid sq_thread from submitting any further
SQEs. Instead they just get discarded when we exit.

Signed-off-by: Xiaoguang Wang <xiaoguang.wang@linux.alibaba.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

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Xiaoguang Wang 2020-05-20 15:35:03 +08:00 • committed by Jens Axboe

parent 310672552f

commit 6b668c9b7f

1 changed files with 2 additions and 11 deletions

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fs/io_uring.c

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