diff --git a/Documentation/topics/dpdk/vhost-user.rst b/Documentation/topics/dpdk/vhost-user.rst
index 368f44520..724aa62f6 100644
--- a/Documentation/topics/dpdk/vhost-user.rst
+++ b/Documentation/topics/dpdk/vhost-user.rst
@@ -350,6 +350,31 @@ The default value is ``false``.
.. _dpdk-testpmd:
+vhost-user-client tx retries config
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+For vhost-user-client interfaces, the max amount of retries can be changed from
+the default 8 by setting ``tx-retries-max``.
+
+The minimum is 0 which means there will be no retries and if any packets in
+each batch cannot be sent immediately they will be dropped. The maximum is 32,
+which would mean that after the first packet(s) in the batch was sent there
+could be a maximum of 32 more retries.
+
+Retries can help with avoiding packet loss when temporarily unable to send to a
+vhost interface because the virtqueue is full. However, spending more time
+retrying to send to one interface, will reduce the time available for rx/tx and
+processing packets on other interfaces, so some tuning may be required for best
+performance.
+
+Tx retries max can be set for vhost-user-client ports::
+
+ $ ovs-vsctl set Interface vhost-client-1 options:tx-retries-max=0
+
+.. note::
+
+ Configurable vhost tx retries are not supported with vhost-user ports.
+
DPDK in the Guest
-----------------
@@ -495,6 +520,9 @@ there will be a retry, with a default maximum of 8 occurring. If at any time no
packets can be sent, it may mean the guest is not accepting packets, so there
are no (more) retries.
+For information about configuring the maximum amount of tx retries for
+vhost-user-client interfaces see `vhost-user-client tx retries config`_.
+
.. note::
Maximum vhost tx batch size is defined by NETDEV_MAX_BURST, and is currently
diff --git a/NEWS b/NEWS
index 6db1af8b1..81130e667 100644
--- a/NEWS
+++ b/NEWS
@@ -7,6 +7,8 @@ Post-v2.11.0
* OVS validated with DPDK 18.11.2 which is the new minimal supported
version.
* DPDK 18.11.1 and lower is no longer supported.
+ * New option 'tx-retries-max' to set the maximum amount of vhost tx
+ retries that can be made.
- OpenFlow:
* All features required by OpenFlow 1.5 are now implemented, so
ovs-vswitchd now enables OpenFlow 1.5 by default (in addition to
diff --git a/lib/netdev-dpdk.c b/lib/netdev-dpdk.c
index 51a885270..48057835f 100644
--- a/lib/netdev-dpdk.c
+++ b/lib/netdev-dpdk.c
@@ -164,7 +164,13 @@ BUILD_ASSERT_DECL((MAX_NB_MBUF / ROUND_DOWN_POW2(MAX_NB_MBUF / MIN_NB_MBUF))
typedef uint16_t dpdk_port_t;
#define DPDK_PORT_ID_FMT "%"PRIu16
-#define VHOST_ENQ_RETRY_NUM 8
+/* Minimum amount of vhost tx retries, effectively a disable. */
+#define VHOST_ENQ_RETRY_MIN 0
+/* Maximum amount of vhost tx retries. */
+#define VHOST_ENQ_RETRY_MAX 32
+/* Legacy default value for vhost tx retries. */
+#define VHOST_ENQ_RETRY_DEF 8
+
#define IF_NAME_SZ (PATH_MAX > IFNAMSIZ ? PATH_MAX : IFNAMSIZ)
static const struct rte_eth_conf port_conf = {
@@ -417,7 +423,9 @@ struct netdev_dpdk {
/* True if vHost device is 'up' and has been reconfigured at least once */
bool vhost_reconfigured;
- /* 3 pad bytes here. */
+
+ atomic_uint8_t vhost_tx_retries_max;
+ /* 2 pad bytes here. */
);
PADDED_MEMBERS(CACHE_LINE_SIZE,
@@ -1261,6 +1269,8 @@ vhost_common_construct(struct netdev *netdev)
return ENOMEM;
}
+ atomic_init(&dev->vhost_tx_retries_max, VHOST_ENQ_RETRY_DEF);
+
return common_construct(netdev, DPDK_ETH_PORT_ID_INVALID,
DPDK_DEV_VHOST, socket_id);
}
@@ -1921,6 +1931,7 @@ netdev_dpdk_vhost_client_set_config(struct netdev *netdev,
{
struct netdev_dpdk *dev = netdev_dpdk_cast(netdev);
const char *path;
+ int max_tx_retries, cur_max_tx_retries;
ovs_mutex_lock(&dev->mutex);
if (!(dev->vhost_driver_flags & RTE_VHOST_USER_CLIENT)) {
@@ -1937,6 +1948,19 @@ netdev_dpdk_vhost_client_set_config(struct netdev *netdev,
netdev_request_reconfigure(netdev);
}
}
+
+ max_tx_retries = smap_get_int(args, "tx-retries-max",
+ VHOST_ENQ_RETRY_DEF);
+ if (max_tx_retries < VHOST_ENQ_RETRY_MIN
+ || max_tx_retries > VHOST_ENQ_RETRY_MAX) {
+ max_tx_retries = VHOST_ENQ_RETRY_DEF;
+ }
+ atomic_read_relaxed(&dev->vhost_tx_retries_max, &cur_max_tx_retries);
+ if (max_tx_retries != cur_max_tx_retries) {
+ atomic_store_relaxed(&dev->vhost_tx_retries_max, max_tx_retries);
+ VLOG_INFO("Max Tx retries for vhost device '%s' set to %d",
+ netdev_get_name(netdev), max_tx_retries);
+ }
ovs_mutex_unlock(&dev->mutex);
return 0;
@@ -2350,6 +2374,7 @@ __netdev_dpdk_vhost_send(struct netdev *netdev, int qid,
unsigned int total_pkts = cnt;
unsigned int dropped = 0;
int i, retries = 0;
+ int max_retries = VHOST_ENQ_RETRY_MIN;
int vid = netdev_dpdk_get_vid(dev);
qid = dev->tx_q[qid % netdev->n_txq].map;
@@ -2379,18 +2404,25 @@ __netdev_dpdk_vhost_send(struct netdev *netdev, int qid,
cnt -= tx_pkts;
/* Prepare for possible retry.*/
cur_pkts = &cur_pkts[tx_pkts];
+ if (OVS_UNLIKELY(cnt && !retries)) {
+ /*
+ * Read max retries as there are packets not sent
+ * and no retries have already occurred.
+ */
+ atomic_read_relaxed(&dev->vhost_tx_retries_max, &max_retries);
+ }
} else {
/* No packets sent - do not retry.*/
break;
}
- } while (cnt && (retries++ < VHOST_ENQ_RETRY_NUM));
+ } while (cnt && (retries++ < max_retries));
rte_spinlock_unlock(&dev->tx_q[qid].tx_lock);
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);
+ dev->tx_retries += MIN(retries, max_retries);
rte_spinlock_unlock(&dev->stats_lock);
out:
diff --git a/vswitchd/vswitch.xml b/vswitchd/vswitch.xml
index dc31b282d..6d99f7c27 100644
--- a/vswitchd/vswitch.xml
+++ b/vswitchd/vswitch.xml
@@ -3127,6 +3127,18 @@ ovs-vsctl add-port br0 p0 -- set Interface p0 type=patch options:peer=p1 \
+
+
+ The value specifies the maximum amount of vhost tx retries that can
+ be made while trying to send a batch of packets to an interface.
+ Only supported by dpdkvhostuserclient interfaces.
+
+
+ Default value is 8.
+
+
+