udp: add explicit config for GRO (#15545)

GRO is now configurable and defaults to disabled for server sockets and
enabled for client sockets.

Fixes https://github.com/envoyproxy/envoy/issues/15418

Signed-off-by: Matt Klein <mklein@lyft.com>

Mirrored from https://github.com/envoyproxy/envoy @ fb9dd7cc3479e244414bf4702bdbca0fdee7840c

envoy/config/core/v3/udp_socket_config.proto

@@ -21,4 +21,11 @@ message UdpSocketConfig {
   // defaults to 1500 bytes.
   google.protobuf.UInt64Value max_rx_datagram_size = 1
       [(validate.rules).uint64 = {lt: 65536 gt: 0}];
+
+  // Configures whether Generic Receive Offload (GRO)
+  // <https://en.wikipedia.org/wiki/Large_receive_offload>_ is preferred when reading from the
+  // UDP socket. The default is context dependent and is documented where UdpSocketConfig is used.
+  // This option affects performance but not functionality. If GRO is not supported by the operating
+  // system, non-GRO receive will be used.
+  google.protobuf.BoolValue prefer_gro = 2;
 }

envoy/config/core/v4alpha/udp_socket_config.proto

@@ -25,4 +25,11 @@ message UdpSocketConfig {
   // defaults to 1500 bytes.
   google.protobuf.UInt64Value max_rx_datagram_size = 1
       [(validate.rules).uint64 = {lt: 65536 gt: 0}];
+
+  // Configures whether Generic Receive Offload (GRO)
+  // <https://en.wikipedia.org/wiki/Large_receive_offload>_ is preferred when reading from the
+  // UDP socket. The default is context dependent and is documented where UdpSocketConfig is used.
+  // This option affects performance but not functionality. If GRO is not supported by the operating
+  // system, non-GRO receive will be used.
+  google.protobuf.BoolValue prefer_gro = 2;
 }

envoy/config/listener/v3/udp_listener_config.proto

@@ -36,7 +36,10 @@ message UdpListenerConfig {
   // [#comment:TODO(#12829): Remove this as an extension point.]
   core.v3.TypedExtensionConfig listener_config = 4;
 
-  // UDP socket configuration for the listener.
+  // UDP socket configuration for the listener. The default for
+  // :ref:`prefer_gro <envoy_v3_api_field_config.core.v3.UdpSocketConfig.prefer_gro>` is false for
+  // listener sockets. If receiving a large amount of datagrams from a small number of sources, it
+  // may be worthwhile to enable this option after performance testing.
   core.v3.UdpSocketConfig downstream_socket_config = 5;
 
   // If the protocol in the listener socket address in :ref:`protocol

envoy/config/listener/v4alpha/udp_listener_config.proto

@@ -36,7 +36,10 @@ message UdpListenerConfig {
   // [#comment:TODO(#12829): Remove this as an extension point.]
   core.v4alpha.TypedExtensionConfig listener_config = 4;
 
-  // UDP socket configuration for the listener.
+  // UDP socket configuration for the listener. The default for
+  // :ref:`prefer_gro <envoy_v3_api_field_config.core.v3.UdpSocketConfig.prefer_gro>` is false for
+  // listener sockets. If receiving a large amount of datagrams from a small number of sources, it
+  // may be worthwhile to enable this option after performance testing.
   core.v4alpha.UdpSocketConfig downstream_socket_config = 5;
 
   // If the protocol in the listener socket address in :ref:`protocol

envoy/extensions/filters/udp/udp_proxy/v3/udp_proxy.proto

@@ -72,6 +72,8 @@ message UdpProxyConfig {
   // limited to 1.
   repeated HashPolicy hash_policies = 5 [(validate.rules).repeated = {max_items: 1}];
 
-  // UDP socket configuration for upstream sockets.
+  // UDP socket configuration for upstream sockets. The default for
+  // :ref:`prefer_gro <envoy_v3_api_field_config.core.v3.UdpSocketConfig.prefer_gro>` is true for upstream
+  // sockets as the assumption is datagrams will be received from a single source.
   config.core.v3.UdpSocketConfig upstream_socket_config = 6;
 }