netdev-dpdk: Remove Rx checksum reconfigure.

Rx checksum offload is enabled by default on DPDK physical NICs
where available, with reconfiguration through
options:rx-checksum-offload. However, changing rx-checksum-offload
did not result in a reconfiguration of the NIC and wrong status is
reported for it.

As there seems to be diminishing reasons why a user would want
to disable Rx checksum offload, just remove the broken reconfiguration
option.

Fixes: 1a2bb11817 ("netdev-dpdk: Enable Rx checksum offloading feature on DPDK physical ports.")
Reported-by: Kevin Traynor <ktraynor@redhat.com>
Suggested-by: Sugesh Chandran <sugesh.chandran@intel.com>
Acked-by: Darrell Ball <dlu998@gmail.com>
Tested-by: Sugesh Chandran <sugesh.chandran@intel.com>
Signed-off-by: Kevin Traynor <ktraynor@redhat.com>
Signed-off-by: Ben Pfaff <blp@ovn.org>

Documentation/howto/dpdk.rst

@@ -276,27 +276,12 @@ common for use cases involving East-West traffic only.
 Rx Checksum Offload
 -------------------
 
-By default, DPDK physical ports are enabled with Rx checksum offload. Rx
+By default, DPDK physical ports are enabled with Rx checksum offload.
-checksum offload can be configured on a DPDK physical port either when adding
-or at run time.
-
-To disable Rx checksum offload when adding a DPDK port dpdk-p0::
-
-    $ ovs-vsctl add-port br0 dpdk-p0 -- set Interface dpdk-p0 type=dpdk \
-      options:dpdk-devargs=0000:01:00.0 options:rx-checksum-offload=false
-
-Similarly to disable the Rx checksum offloading on a existing DPDK port dpdk-p0::
-
-    $ ovs-vsctl set Interface dpdk-p0 options:rx-checksum-offload=false
 
 Rx checksum offload can offer performance improvement only for tunneling
 traffic in OVS-DPDK because the checksum validation of tunnel packets is
 offloaded to the NIC. Also enabling Rx checksum may slightly reduce the
 performance of non-tunnel traffic, specifically for smaller size packet.
-DPDK vectorization is disabled when checksum offloading is configured on DPDK
-physical ports which in turn effects the non-tunnel traffic performance.
-So it is advised to turn off the Rx checksum offload for non-tunnel traffic use
-cases to achieve the best performance.
 
 .. _extended-statistics:
 

lib/netdev-dpdk.c

@@ -718,29 +718,6 @@ dpdk_eth_dev_queue_setup(struct netdev_dpdk *dev, int n_rxq, int n_txq)
     return diag;
 }
 
-static void
-dpdk_eth_checksum_offload_configure(struct netdev_dpdk *dev)
-    OVS_REQUIRES(dev->mutex)
-{
-    struct rte_eth_dev_info info;
-    bool rx_csum_ol_flag = false;
-    uint32_t rx_chksm_offload_capa = DEV_RX_OFFLOAD_UDP_CKSUM |
-                                     DEV_RX_OFFLOAD_TCP_CKSUM |
-                                     DEV_RX_OFFLOAD_IPV4_CKSUM;
-    rte_eth_dev_info_get(dev->port_id, &info);
-    rx_csum_ol_flag = (dev->hw_ol_features & NETDEV_RX_CHECKSUM_OFFLOAD) != 0;
-
-    if (rx_csum_ol_flag &&
-        (info.rx_offload_capa & rx_chksm_offload_capa) !=
-         rx_chksm_offload_capa) {
-        VLOG_WARN_ONCE("Rx checksum offload is not supported on device %"PRIu8,
-                       dev->port_id);
-        dev->hw_ol_features &= ~NETDEV_RX_CHECKSUM_OFFLOAD;
-        return;
-    }
-    netdev_request_reconfigure(&dev->up);
-}
-
 static void
 dpdk_eth_flow_ctrl_setup(struct netdev_dpdk *dev) OVS_REQUIRES(dev->mutex)
 {
@@ -759,9 +736,21 @@ dpdk_eth_dev_init(struct netdev_dpdk *dev)
     struct ether_addr eth_addr;
     int diag;
     int n_rxq, n_txq;
+    uint32_t rx_chksm_offload_capa = DEV_RX_OFFLOAD_UDP_CKSUM |
+                                     DEV_RX_OFFLOAD_TCP_CKSUM |
+                                     DEV_RX_OFFLOAD_IPV4_CKSUM;
 
     rte_eth_dev_info_get(dev->port_id, &info);
 
+    if ((info.rx_offload_capa & rx_chksm_offload_capa) !=
+            rx_chksm_offload_capa) {
+        VLOG_WARN_ONCE("Rx checksum offload is not supported on device %"PRIu8,
+                        dev->port_id);
+        dev->hw_ol_features &= ~NETDEV_RX_CHECKSUM_OFFLOAD;
+    } else {
+        dev->hw_ol_features |= NETDEV_RX_CHECKSUM_OFFLOAD;
+    }
+
     n_rxq = MIN(info.max_rx_queues, dev->up.n_rxq);
     n_txq = MIN(info.max_tx_queues, dev->up.n_txq);
 
@@ -1209,8 +1198,6 @@ netdev_dpdk_set_config(struct netdev *netdev, const struct smap *args,
         {RTE_FC_NONE,     RTE_FC_TX_PAUSE},
         {RTE_FC_RX_PAUSE, RTE_FC_FULL    }
     };
-    bool rx_chksm_ofld;
-    bool temp_flag;
     const char *new_devargs;
     int err = 0;
 
@@ -1292,16 +1279,6 @@ netdev_dpdk_set_config(struct netdev *netdev, const struct smap *args,
         dpdk_eth_flow_ctrl_setup(dev);
     }
 
-    /* Rx checksum offload configuration */
-    /* By default the Rx checksum offload is ON */
-    rx_chksm_ofld = smap_get_bool(args, "rx-checksum-offload", true);
-    temp_flag = (dev->hw_ol_features & NETDEV_RX_CHECKSUM_OFFLOAD)
-                        != 0;
-    if (temp_flag != rx_chksm_ofld) {
-        dev->hw_ol_features ^= NETDEV_RX_CHECKSUM_OFFLOAD;
-        dpdk_eth_checksum_offload_configure(dev);
-    }
-
 out:
     ovs_mutex_unlock(&dev->mutex);
     ovs_mutex_unlock(&dpdk_mutex);

vswitchd/vswitch.xml

@@ -3480,20 +3480,6 @@
       </column>
     </group>
 
-    <group title="Rx Checksum Offload Configuration">
-      <p>
-        The checksum validation on the incoming packets are performed on NIC
-        using Rx checksum offload feature. Implemented only for <code>dpdk
-        </code>physical interfaces.
-      </p>
-
-      <column name="options" key="rx-checksum-offload"
-              type='{"type": "boolean"}'>
-        Set to <code>false</code> to disble Rx checksum offloading on <code>
-        dpdk</code>physical ports. By default, Rx checksum offload is enabled.
-      </column>
-    </group>
-
     <group title="Common Columns">
       The overall purpose of these columns is described under <code>Common
       Columns</code> at the beginning of this document.