netdev-dpdk: Add custom stat for vhost tx retries.

vhost tx retries may occur, and it can be a sign that
the guest is not optimally configured.

Add a custom stat so a user will know if vhost tx retries are
occurring and hence give a hint that guest config should be
examined.

Signed-off-by: Kevin Traynor <ktraynor@redhat.com>
Signed-off-by: Ian Stokes <ian.stokes@intel.com>

diff --git a/Documentation/topics/dpdk/vhost-user.rst b/Documentation/topics/dpdk/vhost-user.rst
index 5f393aced8f3687a275ed7b0e47dcefe2d153e65..368f445203b32f016c93c3a98e3f1787ad110a21 100644 (file)
--- a/Documentation/topics/dpdk/vhost-user.rst
+++ b/Documentation/topics/dpdk/vhost-user.rst
@@ -520,6 +520,11 @@ example with ``testpmd`` the command line argument can be used::
 The guest should also have sufficient cores dedicated for consuming and
 processing packets at the required rate.
 
+The amount of Tx retries on a vhost-user or vhost-user-client interface can be
+shown with::
+
+  $ ovs-vsctl get Interface dpdkvhostclient0 statistics:tx_retries
+
 vhost-user Dequeue Zero Copy (experimental)
 -------------------------------------------
 

diff --git a/lib/netdev-dpdk.c b/lib/netdev-dpdk.c
index a380b6ffefd46cc8c65b2d99e52b064056e135a6..51a88527085d819d3a59e23cd688539a2cb6b3ef 100644 (file)
--- a/lib/netdev-dpdk.c
+++ b/lib/netdev-dpdk.c
@@ -138,6 +138,12 @@ BUILD_ASSERT_DECL((MAX_NB_MBUF / ROUND_DOWN_POW2(MAX_NB_MBUF / MIN_NB_MBUF))
 #define XSTAT_RX_FRAGMENTED_ERRORS       "rx_fragmented_errors"
 #define XSTAT_RX_JABBER_ERRORS           "rx_jabber_errors"
 
+/* Size of vHost custom stats. */
+#define VHOST_CUSTOM_STATS_SIZE          1
+
+/* Names of vHost custom stats. */
+#define VHOST_STAT_TX_RETRIES            "tx_retries"
+
 #define SOCKET0              0
 
 /* Default size of Physical NIC RXQ */
@@ -433,9 +439,11 @@ struct netdev_dpdk {
 
     PADDED_MEMBERS(CACHE_LINE_SIZE,
         struct netdev_stats stats;
+        /* Custom stat for retries when unable to transmit. */
+        uint64_t tx_retries;
         /* Protects stats */
         rte_spinlock_t stats_lock;
-        /* 44 pad bytes here. */
+        /* 4 pad bytes here. */
     );
 
     PADDED_MEMBERS(CACHE_LINE_SIZE,
@@ -1189,6 +1197,8 @@ common_construct(struct netdev *netdev, dpdk_port_t port_no,
     dev->rte_xstats_ids = NULL;
     dev->rte_xstats_ids_size = 0;
 
+    dev->tx_retries = 0;
+
     return 0;
 }
 
@@ -2380,6 +2390,7 @@ __netdev_dpdk_vhost_send(struct netdev *netdev, int qid,
     rte_spinlock_lock(&dev->stats_lock);
     netdev_dpdk_vhost_update_tx_counters(&dev->stats, pkts, total_pkts,
                                          cnt + dropped);
+    dev->tx_retries += MIN(retries, VHOST_ENQ_RETRY_NUM);
     rte_spinlock_unlock(&dev->stats_lock);
 
 out:
@@ -2817,6 +2828,29 @@ netdev_dpdk_get_custom_stats(const struct netdev *netdev,
     return 0;
 }
 
+static int
+netdev_dpdk_vhost_get_custom_stats(const struct netdev *netdev,
+                                   struct netdev_custom_stats *custom_stats)
+{
+    struct netdev_dpdk *dev = netdev_dpdk_cast(netdev);
+
+    ovs_mutex_lock(&dev->mutex);
+
+    custom_stats->size = VHOST_CUSTOM_STATS_SIZE;
+    custom_stats->counters = xcalloc(custom_stats->size,
+                                     sizeof *custom_stats->counters);
+    ovs_strlcpy(custom_stats->counters[0].name, VHOST_STAT_TX_RETRIES,
+                NETDEV_CUSTOM_STATS_NAME_SIZE);
+
+    rte_spinlock_lock(&dev->stats_lock);
+    custom_stats->counters[0].value = dev->tx_retries;
+    rte_spinlock_unlock(&dev->stats_lock);
+
+    ovs_mutex_unlock(&dev->mutex);
+
+    return 0;
+}
+
 static int
 netdev_dpdk_get_features(const struct netdev *netdev,
                          enum netdev_features *current,
@@ -4397,6 +4431,7 @@ static const struct netdev_class dpdk_vhost_class = {
     .send = netdev_dpdk_vhost_send,
     .get_carrier = netdev_dpdk_vhost_get_carrier,
     .get_stats = netdev_dpdk_vhost_get_stats,
+    .get_custom_stats = netdev_dpdk_vhost_get_custom_stats,
     .get_status = netdev_dpdk_vhost_user_get_status,
     .reconfigure = netdev_dpdk_vhost_reconfigure,
     .rxq_recv = netdev_dpdk_vhost_rxq_recv,
@@ -4412,6 +4447,7 @@ static const struct netdev_class dpdk_vhost_client_class = {
     .send = netdev_dpdk_vhost_send,
     .get_carrier = netdev_dpdk_vhost_get_carrier,
     .get_stats = netdev_dpdk_vhost_get_stats,
+    .get_custom_stats = netdev_dpdk_vhost_get_custom_stats,
     .get_status = netdev_dpdk_vhost_user_get_status,
     .reconfigure = netdev_dpdk_vhost_client_reconfigure,
     .rxq_recv = netdev_dpdk_vhost_rxq_recv,