[dpdk-dev] [PATCH] examples/ip_fragmentation: support bigger packets

[Noa Ezra]

Adding MTU and mbuf size configuration to the application's command
line, in order to be able to receive all packet sizes by the NIC and
DPDK application.
The maximum transmission unit (MTU) is the largest size packet in
bytes that can be sent on the network, therefore before adding MTU
parameter, the NIC could not receive packets larger than 1500 bytes,
which is the default MTU size.
The mbuf is the memory buffer that contains the packet. Before adding
mbuf parameter, the DPDK application could not receive packets larger
than 2KB, which is the default mbuf size.

Signed-off-by: Noa Ezra <noae at mellanox.com>
---
 doc/guides/sample_app_ug/ip_frag.rst | 18 ++++++++-
 examples/ip_fragmentation/main.c     | 77 +++++++++++++++++++++++++++++++++---
 2 files changed, 88 insertions(+), 7 deletions(-)

diff --git a/doc/guides/sample_app_ug/ip_frag.rst b/doc/guides/sample_app_ug/ip_frag.rst
index 7914a97..13933c7 100644
--- a/doc/guides/sample_app_ug/ip_frag.rst
+++ b/doc/guides/sample_app_ug/ip_frag.rst
@@ -53,7 +53,7 @@ Application usage:
 
 .. code-block:: console
 
-    ./build/ip_fragmentation [EAL options] -- -p PORTMASK [-q NQ]
+    ./build/ip_fragmentation [EAL options] -- -p PORTMASK [-q NQ] [-b MBUFSIZE] [-m MTUSIZE]
 
 where:
 
@@ -61,6 +61,15 @@ where:
 
 *   -q NQ is the number of queue (=ports) per lcore (the default is 1)
 
+*   -b MBUFSIZE is the mbuf size in bytes (the default is 2048)
+
+*   -m MTUSIZE is the mtu size in bytes (the default is 1500)
+
+The MTU is the maximum size of a single data unit that can be transmitted over the network, therefore it must be
+greater than the requested max packet size, otherwise the NIC won't be able to get the packet.
+The mbuf is a buffer that is used by the DPDK application to store message buffers.If not using scatter then the
+mbuf size must be greater than the requested max packet size, otherwise the DPDK will not be able to receive the
+packet.
 To run the example in linuxapp environment with 2 lcores (2,4) over 2 ports(0,2) with 1 RX queue per lcore:
 
 .. code-block:: console
@@ -96,6 +105,13 @@ To run the example in linuxapp environment with 1 lcore (4) over 2 ports(0,2) wi
 
     ./build/ip_fragmentation -l 4 -n 3 -- -p 5 -q 2
 
+To run the example with defined MTU size 4000 bytes and mbuf size 9000 byes:
+
+.. code-block:: console
+
+    ./build/ip_fragmentation -l 4 -n 3 -- -p 5 -m 4000 -b 9000
+
+
 To test the application, flows should be set up in the flow generator that match the values in the
 l3fwd_ipv4_route_array and/or l3fwd_ipv6_route_array table.
 
diff --git a/examples/ip_fragmentation/main.c b/examples/ip_fragmentation/main.c
index 17a877d..0cf23b4 100644
--- a/examples/ip_fragmentation/main.c
+++ b/examples/ip_fragmentation/main.c
@@ -111,6 +111,10 @@
 
 static int rx_queue_per_lcore = 1;
 
+static int mbuf_size = RTE_MBUF_DEFAULT_BUF_SIZE;
+
+static int mtu_size = ETHER_MTU;
+
 #define MBUF_TABLE_SIZE  (2 * MAX(MAX_PKT_BURST, MAX_PACKET_FRAG))
 
 struct mbuf_table {
@@ -425,7 +429,6 @@ struct rte_lpm6_config lpm6_config = {
 		 * Read packet from RX queues
 		 */
 		for (i = 0; i < qconf->n_rx_queue; i++) {
-
 			portid = qconf->rx_queue_list[i].portid;
 			nb_rx = rte_eth_rx_burst(portid, 0, pkts_burst,
 						 MAX_PKT_BURST);
@@ -455,9 +458,11 @@ struct rte_lpm6_config lpm6_config = {
 static void
 print_usage(const char *prgname)
 {
-	printf("%s [EAL options] -- -p PORTMASK [-q NQ]\n"
+	printf("%s [EAL options] -- -p PORTMASK [-q NQ] [-b MBUFSIZE] [-m MTUSIZE]\n"
 	       "  -p PORTMASK: hexadecimal bitmask of ports to configure\n"
-	       "  -q NQ: number of queue (=ports) per lcore (default is 1)\n",
+	       "  -q NQ: number of queue (=ports) per lcore (default is 1)\n"
+	       "  -b MBUFSIZE: set the data size of mbuf\n"
+	       "  -m MTUSIZE: set the MTU size\n",
 	       prgname);
 }
 
@@ -496,6 +501,38 @@ struct rte_lpm6_config lpm6_config = {
 	return n;
 }
 
+static int
+parse_mbufsize(const char *q_arg)
+{
+	char *end = NULL;
+	unsigned long mbuf;
+
+	/* parse hexadecimal string */
+	mbuf = strtoul(q_arg, &end, 10);
+	if ((q_arg[0] == '\0') || (end == NULL) || (*end != '\0'))
+		return -1;
+	if (mbuf == 0)
+		return -1;
+
+	return mbuf;
+}
+
+static int
+parse_mtusize(const char *q_arg)
+{
+	char *end = NULL;
+	unsigned long mtu;
+
+	/* parse hexadecimal string */
+	mtu = strtoul(q_arg, &end, 10);
+	if ((q_arg[0] == '\0') || (end == NULL) || (*end != '\0'))
+		return -1;
+	if (mtu == 0)
+		return -1;
+
+	return mtu;
+}
+
 /* Parse the argument given in the command line of the application */
 static int
 parse_args(int argc, char **argv)
@@ -510,7 +547,7 @@ struct rte_lpm6_config lpm6_config = {
 
 	argvopt = argv;
 
-	while ((opt = getopt_long(argc, argvopt, "p:q:",
+	while ((opt = getopt_long(argc, argvopt, "p:q:b:m:",
 				  lgopts, &option_index)) != EOF) {
 
 		switch (opt) {
@@ -534,6 +571,26 @@ struct rte_lpm6_config lpm6_config = {
 			}
 			break;
 
+		/* mbufsize */
+		case 'b':
+			mbuf_size = parse_mbufsize(optarg);
+			if (mbuf_size < 0) {
+				printf("invalid mbuf size\n");
+				print_usage(prgname);
+				return -1;
+			}
+			break;
+
+		/* mtusize */
+		case 'm':
+			mtu_size = parse_mtusize(optarg);
+			if (mtu_size < 0) {
+				printf("invalid mtu size\n");
+				print_usage(prgname);
+				return -1;
+			}
+			break;
+
 		/* long options */
 		case 0:
 			print_usage(prgname);
@@ -777,9 +834,8 @@ struct rte_lpm6_config lpm6_config = {
 			RTE_LOG(INFO, IP_FRAG, "Creating direct mempool on socket %i\n",
 					socket);
 			snprintf(buf, sizeof(buf), "pool_direct_%i", socket);
-
 			mp = rte_pktmbuf_pool_create(buf, NB_MBUF, 32,
-				0, RTE_MBUF_DEFAULT_BUF_SIZE, socket);
+				0, mbuf_size, socket);
 			if (mp == NULL) {
 				RTE_LOG(ERR, IP_FRAG, "Cannot create direct mempool\n");
 				return -1;
@@ -892,6 +948,15 @@ struct rte_lpm6_config lpm6_config = {
 		    dev_info.max_rx_pktlen,
 		    local_port_conf.rxmode.max_rx_pkt_len);
 
+		/* set the mtu to the maximum received packet size */
+		ret = rte_eth_dev_set_mtu(portid, mtu_size);
+		if (ret < 0) {
+			printf("\n");
+			rte_exit(EXIT_FAILURE, "Set MTU failed: "
+				"err=%d, port=%d\n",
+			ret, portid);
+		}
+
 		/* get the lcore_id for this port */
 		while (rte_lcore_is_enabled(rx_lcore_id) == 0 ||
 		       qconf->n_rx_queue == (unsigned)rx_queue_per_lcore) {
-- 
1.8.3.1