examples/vhost: add --dequeue-zero-copy option

[dpdk.git] / examples / vhost / main.c

diff --git a/examples/vhost/main.c b/examples/vhost/main.c
index 195b1db..91000e8 100644 (file)
--- a/examples/vhost/main.c
+++ b/examples/vhost/main.c
@@ -127,6 +127,7 @@ static uint32_t enable_tx_csum;
 static uint32_t enable_tso;
 
 static int client_mode;
+static int dequeue_zero_copy;
 
 /* Specify timeout (in useconds) between retries on RX. */
 static uint32_t burst_rx_delay_time = BURST_RX_WAIT_US;
@@ -294,6 +295,17 @@ port_init(uint8_t port)
 
        rx_ring_size = RTE_TEST_RX_DESC_DEFAULT;
        tx_ring_size = RTE_TEST_TX_DESC_DEFAULT;
+
+       /*
+        * When dequeue zero copy is enabled, guest Tx used vring will be
+        * updated only when corresponding mbuf is freed. Thus, the nb_tx_desc
+        * (tx_ring_size here) must be small enough so that the driver will
+        * hit the free threshold easily and free mbufs timely. Otherwise,
+        * guest Tx vring would be starved.
+        */
+       if (dequeue_zero_copy)
+               tx_ring_size = 64;
+
        tx_rings = (uint16_t)rte_lcore_count();
 
        retval = validate_num_devices(MAX_DEVICES);
@@ -470,7 +482,8 @@ us_vhost_usage(const char *prgname)
        "               --socket-file: The path of the socket file.\n"
        "               --tx-csum [0|1] disable/enable TX checksum offload.\n"
        "               --tso [0|1] disable/enable TCP segment offload.\n"
-       "               --client register a vhost-user socket as client mode.\n",
+       "               --client register a vhost-user socket as client mode.\n"
+       "               --dequeue-zero-copy enables dequeue zero copy\n",
               prgname);
 }
 
@@ -495,6 +508,7 @@ us_vhost_parse_args(int argc, char **argv)
                {"tx-csum", required_argument, NULL, 0},
                {"tso", required_argument, NULL, 0},
                {"client", no_argument, &client_mode, 1},
+               {"dequeue-zero-copy", no_argument, &dequeue_zero_copy, 1},
                {NULL, 0, 0, 0},
        };
 
@@ -1501,6 +1515,9 @@ main(int argc, char *argv[])
        if (client_mode)
                flags |= RTE_VHOST_USER_CLIENT;
 
+       if (dequeue_zero_copy)
+               flags |= RTE_VHOST_USER_DEQUEUE_ZERO_COPY;
+
        /* Register vhost user driver to handle vhost messages. */
        for (i = 0; i < nb_sockets; i++) {
                ret = rte_vhost_driver_register