diff mbox series

[net-next,v8,15/17] io_uring/zcrx: throttle receive requests

Message ID 20241204172204.4180482-16-dw@davidwei.uk (mailing list archive)
State New
Delegated to: Netdev Maintainers
Headers show
Series io_uring zero copy rx | expand

Checks

Context Check Description
netdev/series_format fail Series longer than 15 patches
netdev/tree_selection success Clearly marked for net-next, async
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 4 this patch: 4
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers success CCed 3 of 3 maintainers
netdev/build_clang success Errors and warnings before: 6 this patch: 6
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 305 this patch: 305
netdev/checkpatch warning WARNING: Prefer 'unsigned int' to bare use of 'unsigned'
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

David Wei Dec. 4, 2024, 5:21 p.m. UTC 
From: Pavel Begunkov <asml.silence@gmail.com>

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>
---
 io_uring/net.c  | 2 ++
 io_uring/zcrx.c | 9 +++++++++
 2 files changed, 11 insertions(+)
diff mbox series

Patch

diff --git a/io_uring/net.c b/io_uring/net.c
index f1431317182e..c8d718d7cbe6 100644
--- a/io_uring/net.c
+++ b/io_uring/net.c
@@ -1266,6 +1266,8 @@  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);
diff --git a/io_uring/zcrx.c b/io_uring/zcrx.c
index 8e4b9bfaed99..130583fbe7ca 100644
--- a/io_uring/zcrx.c
+++ b/io_uring/zcrx.c
@@ -24,10 +24,13 @@ 
 
 #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;
 };
 
 struct io_zc_refill_data {
@@ -705,6 +708,9 @@  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;
+
 	if (unlikely(offset < skb_headlen(skb))) {
 		ssize_t copied;
 		size_t to_copy;
@@ -809,6 +815,9 @@  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)