3 files changed, 75 insertions(+), 4 deletions(-)
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
@@ -351,4 +351,29 @@ 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
-----------------
@@ -496,4 +521,7 @@ 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::
diff --git a/lib/netdev-dpdk.c b/lib/netdev-dpdk.c
index d3e02d389..b8592962f 100644
--- a/lib/netdev-dpdk.c
+++ b/lib/netdev-dpdk.c
@@ -165,5 +165,10 @@ 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)
@@ -418,5 +423,7 @@ 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. */
);
@@ -1262,4 +1269,6 @@ vhost_common_construct(struct netdev *netdev)
}
+ atomic_store_relaxed(&dev->vhost_tx_retries_max,
VHOST_ENQ_RETRY_DEF);
+
return common_construct(netdev, DPDK_ETH_PORT_ID_INVALID,
DPDK_DEV_VHOST, socket_id);
@@ -1922,4 +1931,5 @@ 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);
@@ -1938,4 +1948,17 @@ netdev_dpdk_vhost_client_set_config(struct
netdev *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",
+ dev->up.name, max_tx_retries);
+ }
ovs_mutex_unlock(&dev->mutex);
@@ -2351,4 +2374,5 @@ __netdev_dpdk_vhost_send(struct netdev
*netdev, int qid,
unsigned int dropped = 0;
int i, retries = 0;
+ int max_retries = VHOST_ENQ_RETRY_MIN;
int vid = netdev_dpdk_get_vid(dev);
@@ -2380,9 +2404,16 @@ __netdev_dpdk_vhost_send(struct netdev
*netdev, int qid,
/* 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);
@@ -2391,5 +2422,5 @@ __netdev_dpdk_vhost_send(struct netdev *netdev,
int qid,
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);
diff --git a/vswitchd/vswitch.xml b/vswitchd/vswitch.xml
index 69fce7ffb..5b4c13b64 100644
--- a/vswitchd/vswitch.xml
+++ b/vswitchd/vswitch.xml
@@ -3120,4 +3120,16 @@ ovs-vsctl add-port br0 p0 -- set Interface p0
type=patch options:peer=p1 \
</column>
+ <column name="options" key="tx-retries-max"
+ type='{"type": "integer", "minInteger": 0,
"maxInteger": 32}'>
+ <p>
+ 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.
+ </p>
+ <p>
+ Default value is 8.
+ </p>
+ </column>
+
<column name="options" key="n_rxq_desc"
type='{"type": "integer", "minInteger": 1,
"maxInteger": 4096}'>
