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io_uring/napi: postpone napi timeout adjustment

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Remove io_napi_adjust_timeout() and move the adjustments out of the
common path into __io_napi_busy_loop(). Now the limit it's calculated
based on struct io_wait_queue::timeout, for which we query current time
another time. The overhead shouldn't be a problem, it's a polling path,
however that can be optimised later by additionally saving the delta
time value in io_cqring_wait().

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/88e14686e245b3b42ff90a3c4d70895d48676206.1723039801.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Pavel Begunkov
2024-08-07 15:18:12 +01:00
committed by Jens Axboe
parent 489b80060c
commit d5cce407e4
3 changed files with 7 additions and 38 deletions
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28
io_uring/napi.c
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@@ -269,27 +269,6 @@ int io_unregister_napi(struct io_ring_ctx *ctx, void __user *arg)
return 0;
}
/*
* __io_napi_adjust_timeout() - adjust busy loop timeout
* @ctx: pointer to io-uring context structure
* @iowq: pointer to io wait queue
* @ts: pointer to timespec or NULL
*
* Adjust the busy loop timeout according to timespec and busy poll timeout.
* If the specified NAPI timeout is bigger than the wait timeout, then adjust
* the NAPI timeout accordingly.
*/
void __io_napi_adjust_timeout(struct io_ring_ctx *ctx, struct io_wait_queue *iowq,
ktime_t to_wait)
{
ktime_t poll_dt = READ_ONCE(ctx->napi_busy_poll_dt);
if (to_wait)
poll_dt = min(poll_dt, to_wait);
iowq->napi_busy_poll_dt = poll_dt;
}
/*
* __io_napi_busy_loop() - execute busy poll loop
* @ctx: pointer to io-uring context structure
@@ -302,6 +281,13 @@ void __io_napi_busy_loop(struct io_ring_ctx *ctx, struct io_wait_queue *iowq)
if (ctx->flags & IORING_SETUP_SQPOLL)
return;
iowq->napi_busy_poll_dt = READ_ONCE(ctx->napi_busy_poll_dt);
if (iowq->timeout != KTIME_MAX) {
ktime_t dt = ktime_sub(iowq->timeout, ktime_get());
iowq->napi_busy_poll_dt = min_t(u64, iowq->napi_busy_poll_dt, dt);
}
iowq->napi_prefer_busy_poll = READ_ONCE(ctx->napi_prefer_busy_poll);
io_napi_blocking_busy_loop(ctx, iowq);
}