[PATCH liburing v2 0/4] zcrx refill queue allocation modes

[PATCH liburing v2 0/4] zcrx refill queue allocation modes

[Pavel Begunkov]

Random patches for zcrx. Path 1 removes oneshot mode as it doesn't
give a good example, and Patch 3 allows to kernel allocations for
the refill queue.

v2: rework oneshot/size limiting instead of removal
    fix flipped allocation mode check

Pavel Begunkov (4):
  examples/zcrx: consolidate add_recvzc variants
  examples/zcrx: rework size limiting
  examples/zcrx: constants for request types
  examples/zcrx: add refill queue allocation modes

 examples/zcrx.c | 119 +++++++++++++++++++++++++++---------------------
 1 file changed, 68 insertions(+), 51 deletions(-)

-- 
2.48.1

[PATCH liburing v2 1/4] examples/zcrx: consolidate add_recvzc variants

[Pavel Begunkov]

Pass len to add_recvzc, 0 means it's unlimited, and kill the oneshot
variant.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 examples/zcrx.c | 21 ++++-----------------
 1 file changed, 4 insertions(+), 17 deletions(-)

diff --git a/examples/zcrx.c b/examples/zcrx.c
index 32d9e4ae..727943c4 100644
--- a/examples/zcrx.c
+++ b/examples/zcrx.c
@@ -140,17 +140,7 @@ static void add_accept(struct io_uring *ring, int sockfd)
 	sqe->user_data = 1;
 }
 
-static void add_recvzc(struct io_uring *ring, int sockfd)
-{
-	struct io_uring_sqe *sqe = io_uring_get_sqe(ring);
-
-	io_uring_prep_rw(IORING_OP_RECV_ZC, sqe, sockfd, NULL, 0, 0);
-	sqe->ioprio |= IORING_RECV_MULTISHOT;
-	sqe->zcrx_ifq_idx = zcrx_id;
-	sqe->user_data = 2;
-}
-
-static void add_recvzc_oneshot(struct io_uring *ring, int sockfd, size_t len)
+static void add_recvzc(struct io_uring *ring, int sockfd, size_t len)
 {
 	struct io_uring_sqe *sqe = io_uring_get_sqe(ring);
 
@@ -168,10 +158,7 @@ static void process_accept(struct io_uring *ring, struct io_uring_cqe *cqe)
 		t_error(1, 0, "Unexpected second connection");
 
 	connfd = cqe->res;
-	if (cfg_oneshot)
-		add_recvzc_oneshot(ring, connfd, page_size);
-	else
-		add_recvzc(ring, connfd);
+	add_recvzc(ring, connfd, cfg_oneshot ? page_size : 0);
 }
 
 static void verify_data(char *data, size_t size, unsigned long seq)
@@ -207,11 +194,11 @@ static void process_recvzc(struct io_uring *ring, struct io_uring_cqe *cqe)
 
 	if (cfg_oneshot) {
 		if (cqe->res == 0 && cqe->flags == 0 && cfg_oneshot_recvs) {
-			add_recvzc_oneshot(ring, connfd, page_size);
+			add_recvzc(ring, connfd, page_size);
 			cfg_oneshot_recvs--;
 		}
 	} else if (!(cqe->flags & IORING_CQE_F_MORE)) {
-		add_recvzc(ring, connfd);
+		add_recvzc(ring, connfd, 0);
 	}
 
 	rcqe = (struct io_uring_zcrx_cqe *)(cqe + 1);
-- 
2.48.1

[PATCH liburing v2 2/4] examples/zcrx: rework size limiting

[Pavel Begunkov]

zcrx doesn't work in a single shot mode, we can limit the number of
bytes it processes but not the number of cqes. Replace cfg_oneshot with
total byte size limiting.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 examples/zcrx.c | 38 +++++++++++++++-----------------------
 1 file changed, 15 insertions(+), 23 deletions(-)

diff --git a/examples/zcrx.c b/examples/zcrx.c
index 727943c4..5b06bb4c 100644
--- a/examples/zcrx.c
+++ b/examples/zcrx.c
@@ -46,9 +46,8 @@ static long page_size;
 static int cfg_port = 8000;
 static const char *cfg_ifname;
 static int cfg_queue_id = -1;
-static bool cfg_oneshot;
-static int cfg_oneshot_recvs;
 static bool cfg_verify_data = false;
+static size_t cfg_size = 0;
 static struct sockaddr_in6 cfg_addr;
 
 static void *area_ptr;
@@ -158,7 +157,7 @@ static void process_accept(struct io_uring *ring, struct io_uring_cqe *cqe)
 		t_error(1, 0, "Unexpected second connection");
 
 	connfd = cqe->res;
-	add_recvzc(ring, connfd, cfg_oneshot ? page_size : 0);
+	add_recvzc(ring, connfd, cfg_size);
 }
 
 static void verify_data(char *data, size_t size, unsigned long seq)
@@ -176,7 +175,8 @@ static void verify_data(char *data, size_t size, unsigned long seq)
 	}
 }
 
-static void process_recvzc(struct io_uring *ring, struct io_uring_cqe *cqe)
+static void process_recvzc(struct io_uring __attribute__((unused)) *ring,
+			   struct io_uring_cqe *cqe)
 {
 	unsigned rq_mask = rq_ring.ring_entries - 1;
 	struct io_uring_zcrx_cqe *rcqe;
@@ -184,22 +184,16 @@ static void process_recvzc(struct io_uring *ring, struct io_uring_cqe *cqe)
 	uint64_t mask;
 	char *data;
 
-	if (cqe->res < 0)
-		t_error(1, 0, "recvzc(): %d", cqe->res);
-
-	if (cqe->res == 0 && cqe->flags == 0 && cfg_oneshot_recvs == 0) {
+	if (!(cqe->flags & IORING_CQE_F_MORE)) {
+		if (!cfg_size || cqe->res != 0)
+			t_error(1, 0, "invalid final recvzc ret %i", cqe->res);
+		if (received != cfg_size)
+			t_error(1, 0, "total receive size mismatch %lu / %lu",
+				received, cfg_size);
 		stop = true;
-		return;
-	}
-
-	if (cfg_oneshot) {
-		if (cqe->res == 0 && cqe->flags == 0 && cfg_oneshot_recvs) {
-			add_recvzc(ring, connfd, page_size);
-			cfg_oneshot_recvs--;
-		}
-	} else if (!(cqe->flags & IORING_CQE_F_MORE)) {
-		add_recvzc(ring, connfd, 0);
 	}
+	if (cqe->res < 0)
+		t_error(1, 0, "recvzc(): %d", cqe->res);
 
 	rcqe = (struct io_uring_zcrx_cqe *)(cqe + 1);
 	mask = (1ULL << IORING_ZCRX_AREA_SHIFT) - 1;
@@ -286,7 +280,7 @@ static void parse_opts(int argc, char **argv)
 	if (argc <= 1)
 		usage(argv[0]);
 
-	while ((c = getopt(argc, argv, "vp:i:q:o:")) != -1) {
+	while ((c = getopt(argc, argv, "vp:i:q:s:")) != -1) {
 		switch (c) {
 		case 'p':
 			cfg_port = strtoul(optarg, NULL, 0);
@@ -294,11 +288,9 @@ static void parse_opts(int argc, char **argv)
 		case 'i':
 			cfg_ifname = optarg;
 			break;
-		case 'o': {
-			cfg_oneshot = true;
-			cfg_oneshot_recvs = strtoul(optarg, NULL, 0);
+		case 's':
+			cfg_size = strtoul(optarg, NULL, 0);
 			break;
-		}
 		case 'q':
 			cfg_queue_id = strtoul(optarg, NULL, 0);
 			break;
-- 
2.48.1

[PATCH liburing v2 3/4] examples/zcrx: constants for request types

[Pavel Begunkov]

Instead of hard coding user_data, name request types we need and use
them.

Reviewed-by: David Wei <dw@davidwei.uk>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 examples/zcrx.c | 22 +++++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)

diff --git a/examples/zcrx.c b/examples/zcrx.c
index 5b06bb4c..e5c3c6ec 100644
--- a/examples/zcrx.c
+++ b/examples/zcrx.c
@@ -43,6 +43,14 @@ static long page_size;
 #define AREA_SIZE (8192 * page_size)
 #define SEND_SIZE (512 * 4096)
 
+#define REQ_TYPE_SHIFT	3
+#define REQ_TYPE_MASK	((1UL << REQ_TYPE_SHIFT) - 1)
+
+enum request_type {
+	REQ_TYPE_ACCEPT		= 1,
+	REQ_TYPE_RX		= 2,
+};
+
 static int cfg_port = 8000;
 static const char *cfg_ifname;
 static int cfg_queue_id = -1;
@@ -136,7 +144,7 @@ static void add_accept(struct io_uring *ring, int sockfd)
 	struct io_uring_sqe *sqe = io_uring_get_sqe(ring);
 
 	io_uring_prep_accept(sqe, sockfd, NULL, NULL, 0);
-	sqe->user_data = 1;
+	sqe->user_data = REQ_TYPE_ACCEPT;
 }
 
 static void add_recvzc(struct io_uring *ring, int sockfd, size_t len)
@@ -146,7 +154,7 @@ static void add_recvzc(struct io_uring *ring, int sockfd, size_t len)
 	io_uring_prep_rw(IORING_OP_RECV_ZC, sqe, sockfd, NULL, len, 0);
 	sqe->ioprio |= IORING_RECV_MULTISHOT;
 	sqe->zcrx_ifq_idx = zcrx_id;
-	sqe->user_data = 2;
+	sqe->user_data = REQ_TYPE_RX;
 }
 
 static void process_accept(struct io_uring *ring, struct io_uring_cqe *cqe)
@@ -217,12 +225,16 @@ static void server_loop(struct io_uring *ring)
 	io_uring_submit_and_wait(ring, 1);
 
 	io_uring_for_each_cqe(ring, head, cqe) {
-		if (cqe->user_data == 1)
+		switch (cqe->user_data & REQ_TYPE_MASK) {
+		case REQ_TYPE_ACCEPT:
 			process_accept(ring, cqe);
-		else if (cqe->user_data == 2)
+			break;
+		case REQ_TYPE_RX:
 			process_recvzc(ring, cqe);
-		else
+			break;
+		default:
 			t_error(1, 0, "unknown cqe");
+		}
 		count++;
 	}
 	io_uring_cq_advance(ring, count);
-- 
2.48.1

[PATCH liburing v2 4/4] examples/zcrx: add refill queue allocation modes

[Pavel Begunkov]

Refill queue creating is backed by the region api, which can either be
user or kernel allocated. Add an option to switch between the modes.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 examples/zcrx.c | 46 ++++++++++++++++++++++++++++++++++++----------
 1 file changed, 36 insertions(+), 10 deletions(-)

diff --git a/examples/zcrx.c b/examples/zcrx.c
index e5c3c6ec..40a4f0ad 100644
--- a/examples/zcrx.c
+++ b/examples/zcrx.c
@@ -39,6 +39,13 @@
 #include "liburing.h"
 #include "helpers.h"
 
+enum {
+	RQ_ALLOC_USER,
+	RQ_ALLOC_KERNEL,
+
+	__RQ_ALLOC_MAX,
+};
+
 static long page_size;
 #define AREA_SIZE (8192 * page_size)
 #define SEND_SIZE (512 * 4096)
@@ -56,6 +63,7 @@ static const char *cfg_ifname;
 static int cfg_queue_id = -1;
 static bool cfg_verify_data = false;
 static size_t cfg_size = 0;
+static unsigned cfg_rq_alloc_mode = RQ_ALLOC_USER;
 static struct sockaddr_in6 cfg_addr;
 
 static void *area_ptr;
@@ -80,6 +88,7 @@ static void setup_zcrx(struct io_uring *ring)
 {
 	unsigned int ifindex;
 	unsigned int rq_entries = 4096;
+	unsigned rq_flags = 0;
 	int ret;
 
 	ifindex = if_nametoindex(cfg_ifname);
@@ -96,19 +105,22 @@ static void setup_zcrx(struct io_uring *ring)
 		t_error(1, 0, "mmap(): zero copy area");
 
 	ring_size = get_refill_ring_size(rq_entries);
-	ring_ptr = mmap(NULL,
-			ring_size,
-			PROT_READ | PROT_WRITE,
-			MAP_ANONYMOUS | MAP_PRIVATE,
-			0,
-			0);
-	if (ring_ptr == MAP_FAILED)
-		t_error(1, 0, "mmap(): refill ring");
+
+	ring_ptr = NULL;
+	if (cfg_rq_alloc_mode == RQ_ALLOC_USER) {
+		ring_ptr = mmap(NULL, ring_size,
+				PROT_READ | PROT_WRITE,
+				MAP_ANONYMOUS | MAP_PRIVATE,
+				0, 0);
+		if (ring_ptr == MAP_FAILED)
+			t_error(1, 0, "mmap(): refill ring");
+		rq_flags |= IORING_MEM_REGION_TYPE_USER;
+	}
 
 	struct io_uring_region_desc region_reg = {
 		.size = ring_size,
 		.user_addr = (__u64)(unsigned long)ring_ptr,
-		.flags = IORING_MEM_REGION_TYPE_USER,
+		.flags = rq_flags,
 	};
 
 	struct io_uring_zcrx_area_reg area_reg = {
@@ -129,6 +141,15 @@ static void setup_zcrx(struct io_uring *ring)
 	if (ret)
 		t_error(1, 0, "io_uring_register_ifq(): %d", ret);
 
+	if (cfg_rq_alloc_mode == RQ_ALLOC_KERNEL) {
+		ring_ptr = mmap(NULL, ring_size,
+				PROT_READ | PROT_WRITE,
+				MAP_SHARED | MAP_POPULATE,
+				ring->ring_fd, region_reg.mmap_offset);
+		if (ring_ptr == MAP_FAILED)
+			t_error(1, 0, "mmap(): refill ring");
+	}
+
 	rq_ring.khead = (unsigned int *)((char *)ring_ptr + reg.offsets.head);
 	rq_ring.ktail = (unsigned int *)((char *)ring_ptr + reg.offsets.tail);
 	rq_ring.rqes = (struct io_uring_zcrx_rqe *)((char *)ring_ptr + reg.offsets.rqes);
@@ -292,7 +313,7 @@ static void parse_opts(int argc, char **argv)
 	if (argc <= 1)
 		usage(argv[0]);
 
-	while ((c = getopt(argc, argv, "vp:i:q:s:")) != -1) {
+	while ((c = getopt(argc, argv, "vp:i:q:s:r:")) != -1) {
 		switch (c) {
 		case 'p':
 			cfg_port = strtoul(optarg, NULL, 0);
@@ -309,6 +330,11 @@ static void parse_opts(int argc, char **argv)
 		case 'v':
 			cfg_verify_data = true;
 			break;
+		case 'r':
+			cfg_rq_alloc_mode = strtoul(optarg, NULL, 0);
+			if (cfg_rq_alloc_mode >= __RQ_ALLOC_MAX)
+				t_error(1, 0, "invalid RQ allocation mode");
+			break;
 		}
 	}
 
-- 
2.48.1

Re: [PATCH liburing v2 0/4] zcrx refill queue allocation modes

[Jens Axboe]

On Mon, 21 Apr 2025 08:25:28 +0100, Pavel Begunkov wrote:
> Random patches for zcrx. Path 1 removes oneshot mode as it doesn't
> give a good example, and Patch 3 allows to kernel allocations for
> the refill queue.
> 
> v2: rework oneshot/size limiting instead of removal
>     fix flipped allocation mode check
> 
> [...]

Applied, thanks!

[1/4] examples/zcrx: consolidate add_recvzc variants
      commit: 17286dbf9017ae6f4c864216b59ab9919268aff6
[2/4] examples/zcrx: rework size limiting
      commit: b10430f9b004a4f1f54c1a4721c80ce3a98996a0
[3/4] examples/zcrx: constants for request types
      commit: 8cee8f8cbf9f91c4dca9298159f2c5c64f898080
[4/4] examples/zcrx: add refill queue allocation modes
      commit: 353fc7dcc61e059ac8890916f41d39df10e5bfa5

Best regards,
-- 
Jens Axboe