From 46ae7eef44f6dfd825a3bcfa43392d3ad9836ada Mon Sep 17 00:00:00 2001 From: Pavel Begunkov Date: Thu, 5 Jan 2023 11:22:28 +0000 Subject: [PATCH] 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 Link: https://lore.kernel.org/r/89f880574eceee6f4899783377ead234df7b3d04.1672916894.git.asml.silence@gmail.com Signed-off-by: Jens Axboe --- io_uring/io_uring.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c index 2ec011f0ba7d..6229a49c0c33 100644 --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -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; }