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

[Pavel Begunkov <asml.silence@gmail.com>]

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