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io_uring: optimise non-timeout waiting 

Unlike the jiffy scheduling version, schedule_hrtimeout() jumps a few
functions before getting into schedule() even if there is no actual
timeout needed. Some tests showed that it takes up to 1% of CPU cycles.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/89f880574eceee6f4899783377ead234df7b3d04.1672916894.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Pavel Begunkov 2023-01-05 11:22:28 +00:00 committed by Jens Axboe
parent 326a9e482e
commit 46ae7eef44
1 changed files with 3 additions and 1 deletions
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4
io_uring/io_uring.c
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@ -2479,7 +2479,9 @@ static inline int io_cqring_wait_schedule(struct io_ring_ctx *ctx,
return -EINTR;
if (unlikely(io_should_wake(iowq)))
return 0;
if (!schedule_hrtimeout(timeout, HRTIMER_MODE_ABS))
if (*timeout == KTIME_MAX)
schedule();
else if (!schedule_hrtimeout(timeout, HRTIMER_MODE_ABS))
return -ETIME;
return 0;
}