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io_uring/zcrx: throttle receive requests

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io_zc_rx_tcp_recvmsg() continues until it fails or there is nothing to
receive. If the other side sends fast enough, we might get stuck in
io_zc_rx_tcp_recvmsg() producing more and more CQEs but not letting the
user to handle them leading to unbound latencies.

Break out of it based on an arbitrarily chosen limit, the upper layer
will either return to userspace or requeue the request.

Reviewed-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: David Wei <dw@davidwei.uk>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Link: https://lore.kernel.org/r/20250215000947.789731-9-dw@davidwei.uk
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Pavel Begunkov
2025-02-14 16:09:43 -08:00
committed by Jens Axboe
parent e0793de24a
commit 931dfae190
2 changed files with 11 additions and 0 deletions
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2
io_uring/net.c
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@@ -1285,6 +1285,8 @@ int io_recvzc(struct io_kiocb *req, unsigned int issue_flags)
if (unlikely(ret <= 0) && ret != -EAGAIN) {
if (ret == -ERESTARTSYS)
ret = -EINTR;
if (ret == IOU_REQUEUE)
return IOU_REQUEUE;
req_set_fail(req);
io_req_set_res(req, ret, 0);

9
io_uring/zcrx.c
View File

@@ -94,10 +94,13 @@ static void io_zcrx_sync_for_device(const struct page_pool *pool,
#define IO_RQ_MAX_ENTRIES 32768
#define IO_SKBS_PER_CALL_LIMIT 20
struct io_zcrx_args {
struct io_kiocb *req;
struct io_zcrx_ifq *ifq;
struct socket *sock;
unsigned nr_skbs;
};
static const struct memory_provider_ops io_uring_pp_zc_ops;
@@ -720,6 +723,9 @@ io_zcrx_recv_skb(read_descriptor_t *desc, struct sk_buff *skb,
int i, copy, end, off;
int ret = 0;
if (unlikely(args->nr_skbs++ > IO_SKBS_PER_CALL_LIMIT))
return -EAGAIN;
start = skb_headlen(skb);
start_off = offset;
@@ -810,6 +816,9 @@ static int io_zcrx_tcp_recvmsg(struct io_kiocb *req, struct io_zcrx_ifq *ifq,
ret = -ENOTCONN;
else
ret = -EAGAIN;
} else if (unlikely(args.nr_skbs > IO_SKBS_PER_CALL_LIMIT) &&
(issue_flags & IO_URING_F_MULTISHOT)) {
ret = IOU_REQUEUE;
} else if (sock_flag(sk, SOCK_DONE)) {
/* Make it to retry until it finally gets 0. */
if (issue_flags & IO_URING_F_MULTISHOT)