netdev-dpdk: Check rx/tx descriptor sizes for device.

By default OVS configures 2048 descriptors for tx and rx queues
on DPDK devices. It also allows the user to configure those values.

If the values used are not acceptable to the device then queue setup
would fail.

The device exposes it's max/min/alignment requirements and OVS
applies some limits also. Use these to ensure an acceptable value
is used for the number of descriptors on a device tx/rx.

If the default or user value is not acceptable, adjust to a suitable
value and log.

Reported-at: https://bugzilla.redhat.com/2119876
Reviewed-by: David Marchand <david.marchand@redhat.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: Kevin Traynor <ktraynor@redhat.com>
Signed-off-by: Ilya Maximets <i.maximets@ovn.org>

lib/netdev-dpdk.c

@@ -1910,18 +1910,56 @@ dpdk_set_rxq_config(struct netdev_dpdk *dev, const struct smap *args)
 
 static void
 dpdk_process_queue_size(struct netdev *netdev, const struct smap *args,
-                        const char *flag, int default_size, int *new_size)
+                        struct rte_eth_dev_info *info, bool is_rx)
 {
-    int queue_size = smap_get_int(args, flag, default_size);
+    struct netdev_dpdk *dev = netdev_dpdk_cast(netdev);
+    struct rte_eth_desc_lim *lim;
+    int default_size, queue_size, cur_size, new_requested_size;
+    int *cur_requested_size;
+    bool reconfig = false;
+
+    if (is_rx) {
+        default_size = NIC_PORT_DEFAULT_RXQ_SIZE;
+        new_requested_size = smap_get_int(args, "n_rxq_desc", default_size);
+        cur_size = dev->rxq_size;
+        cur_requested_size = &dev->requested_rxq_size;
+        lim = info ? &info->rx_desc_lim : NULL;
+    } else {
+        default_size = NIC_PORT_DEFAULT_TXQ_SIZE;
+        new_requested_size = smap_get_int(args, "n_txq_desc", default_size);
+        cur_size = dev->txq_size;
+        cur_requested_size = &dev->requested_txq_size;
+        lim = info ? &info->tx_desc_lim : NULL;
+    }
+
+    queue_size = new_requested_size;
 
+    /* Check for OVS limits. */
     if (queue_size <= 0 || queue_size > NIC_PORT_MAX_Q_SIZE
             || !is_pow2(queue_size)) {
         queue_size = default_size;
     }
 
-    if (queue_size != *new_size) {
-        *new_size = queue_size;
+    if (lim) {
+        /* Check for device limits. */
+        if (lim->nb_align) {
+            queue_size = ROUND_UP(queue_size, lim->nb_align);
+        }
+        queue_size = MIN(queue_size, lim->nb_max);
+        queue_size = MAX(queue_size, lim->nb_min);
+    }
+
+    *cur_requested_size = queue_size;
+
+    if (cur_size != queue_size) {
         netdev_request_reconfigure(netdev);
+        reconfig = true;
+    }
+    if (new_requested_size != queue_size) {
+        VLOG(reconfig ? VLL_INFO : VLL_DBG,
+             "%s: Unable to set the number of %s descriptors to %d. "
+             "Adjusted to %d.", netdev_get_name(netdev),
+             is_rx ? "rx": "tx", new_requested_size, queue_size);
     }
 }
 
@@ -1937,22 +1975,17 @@ netdev_dpdk_set_config(struct netdev *netdev, const struct smap *args,
         {RTE_ETH_FC_NONE,     RTE_ETH_FC_TX_PAUSE},
         {RTE_ETH_FC_RX_PAUSE, RTE_ETH_FC_FULL    }
     };
+    struct rte_eth_dev_info info;
     const char *new_devargs;
     const char *vf_mac;
     int err = 0;
+    int ret;
 
     ovs_mutex_lock(&dpdk_mutex);
     ovs_mutex_lock(&dev->mutex);
 
     dpdk_set_rxq_config(dev, args);
 
-    dpdk_process_queue_size(netdev, args, "n_rxq_desc",
-                            NIC_PORT_DEFAULT_RXQ_SIZE,
-                            &dev->requested_rxq_size);
-    dpdk_process_queue_size(netdev, args, "n_txq_desc",
-                            NIC_PORT_DEFAULT_TXQ_SIZE,
-                            &dev->requested_txq_size);
-
     new_devargs = smap_get(args, "dpdk-devargs");
 
     if (dev->devargs && new_devargs && strcmp(new_devargs, dev->devargs)) {
@@ -2008,6 +2041,11 @@ netdev_dpdk_set_config(struct netdev *netdev, const struct smap *args,
         goto out;
     }
 
+    ret = rte_eth_dev_info_get(dev->port_id, &info);
+
+    dpdk_process_queue_size(netdev, args, !ret ? &info : NULL, true);
+    dpdk_process_queue_size(netdev, args, !ret ? &info : NULL, false);
+
     vf_mac = smap_get(args, "dpdk-vf-mac");
     if (vf_mac) {
         struct eth_addr mac;