examples/vhost: fix launch with physical port

[ upstream commit 917229c ]

dpdk-vhost will fail to launch with a 40G i40e port because
there are not enough mbufs. This patch adds a new option
--total-num-mbufs, through which the user can set larger
mbuf pool to avoid this problem.

Fixes: 4796ad6 ("examples/vhost: import userspace vhost application")

Signed-off-by: Wenwu Ma <wenwux.ma@intel.com>
Reviewed-by: Chenbo Xia <chenbo.xia@intel.com>

examples/vhost/main.c

@@ -33,6 +33,8 @@
 #define MAX_QUEUES 128
 #endif
 
+#define NUM_MBUFS_DEFAULT 0x24000
+
 /* the maximum number of external ports supported */
 #define MAX_SUP_PORTS 1
 
@@ -60,6 +62,9 @@
 /* Maximum long option length for option parsing. */
 #define MAX_LONG_OPT_SZ 64
 
+/* number of mbufs in all pools - if specified on command-line. */
+static int total_num_mbufs = NUM_MBUFS_DEFAULT;
+
 /* mask of enabled ports */
 static uint32_t enabled_port_mask = 0;
 
@@ -463,7 +468,8 @@ us_vhost_usage(const char *prgname)
 	"		--tso [0|1] disable/enable TCP segment offload.\n"
 	"		--client register a vhost-user socket as client mode.\n"
 	"		--dma-type register dma type for your vhost async driver. For example \"ioat\" for now.\n"
-	"		--dmas register dma channel for specific vhost device.\n",
+	"		--dmas register dma channel for specific vhost device.\n"
+	"		--total-num-mbufs [0-N] set the number of mbufs to be allocated in mbuf pools, the default value is 147456.\n",
 	       prgname);
 }
 
@@ -491,7 +497,7 @@ us_vhost_parse_args(int argc, char **argv)
 		{"builtin-net-driver", no_argument, &builtin_net_driver, 1},
 		{"dma-type", required_argument, NULL, 0},
 		{"dmas", required_argument, NULL, 0},
-		{NULL, 0, 0, 0},
+		{"total-num-mbufs", required_argument, NULL, 0},
 	};
 
 	/* Parse command line */
@@ -655,6 +661,21 @@ us_vhost_parse_args(int argc, char **argv)
 				async_vhost_driver = 1;
 			}
 
+
+			if (!strncmp(long_option[option_index].name,
+						"total-num-mbufs", MAX_LONG_OPT_SZ)) {
+				ret = parse_num_opt(optarg, INT32_MAX);
+				if (ret == -1) {
+					RTE_LOG(INFO, VHOST_CONFIG,
+						"Invalid argument for total-num-mbufs [0..N]\n");
+					us_vhost_usage(prgname);
+					return -1;
+				}
+
+				if (total_num_mbufs < ret)
+					total_num_mbufs = ret;
+			}
+
 			break;
 
 			/* Invalid option - print options. */
@@ -1443,57 +1464,6 @@ sigint_handler(__rte_unused int signum)
 	exit(0);
 }
 
-/*
- * While creating an mbuf pool, one key thing is to figure out how
- * many mbuf entries is enough for our use. FYI, here are some
- * guidelines:
- *
- * - Each rx queue would reserve @nr_rx_desc mbufs at queue setup stage
- *
- * - For each switch core (A CPU core does the packet switch), we need
- *   also make some reservation for receiving the packets from virtio
- *   Tx queue. How many is enough depends on the usage. It's normally
- *   a simple calculation like following:
- *
- *       MAX_PKT_BURST * max packet size / mbuf size
- *
- *   So, we definitely need allocate more mbufs when TSO is enabled.
- *
- * - Similarly, for each switching core, we should serve @nr_rx_desc
- *   mbufs for receiving the packets from physical NIC device.
- *
- * - We also need make sure, for each switch core, we have allocated
- *   enough mbufs to fill up the mbuf cache.
- */
-static void
-create_mbuf_pool(uint16_t nr_port, uint32_t nr_switch_core, uint32_t mbuf_size,
-	uint32_t nr_queues, uint32_t nr_rx_desc, uint32_t nr_mbuf_cache)
-{
-	uint32_t nr_mbufs;
-	uint32_t nr_mbufs_per_core;
-	uint32_t mtu = 1500;
-
-	if (mergeable)
-		mtu = 9000;
-	if (enable_tso)
-		mtu = 64 * 1024;
-
-	nr_mbufs_per_core  = (mtu + mbuf_size) * MAX_PKT_BURST /
-			(mbuf_size - RTE_PKTMBUF_HEADROOM);
-	nr_mbufs_per_core += nr_rx_desc;
-	nr_mbufs_per_core  = RTE_MAX(nr_mbufs_per_core, nr_mbuf_cache);
-
-	nr_mbufs  = nr_queues * nr_rx_desc;
-	nr_mbufs += nr_mbufs_per_core * nr_switch_core;
-	nr_mbufs *= nr_port;
-
-	mbuf_pool = rte_pktmbuf_pool_create("MBUF_POOL", nr_mbufs,
-					    nr_mbuf_cache, 0, mbuf_size,
-					    rte_socket_id());
-	if (mbuf_pool == NULL)
-		rte_exit(EXIT_FAILURE, "Cannot create mbuf pool\n");
-}
-
 /*
  * Main function, does initialisation and calls the per-lcore functions.
  */
@@ -1552,8 +1522,11 @@ main(int argc, char *argv[])
 	 * many queues here. We probably should only do allocation for
 	 * those queues we are going to use.
 	 */
-	create_mbuf_pool(valid_num_ports, rte_lcore_count() - 1, MBUF_DATA_SIZE,
-			 MAX_QUEUES, RTE_TEST_RX_DESC_DEFAULT, MBUF_CACHE_SIZE);
+	mbuf_pool = rte_pktmbuf_pool_create("MBUF_POOL", total_num_mbufs,
+					    MBUF_CACHE_SIZE, 0, MBUF_DATA_SIZE,
+					    rte_socket_id());
+	if (mbuf_pool == NULL)
+		rte_exit(EXIT_FAILURE, "Cannot create mbuf pool\n");
 
 	if (vm2vm_mode == VM2VM_HARDWARE) {
 		/* Enable VT loop back to let L2 switch to do it. */