• Alexander Duyck's avatar
    gso: Update tunnel segmentation to support Tx checksum offload · cdbaa0bb
    Alexander Duyck authored
    This change makes it so that the GRE and VXLAN tunnels can make use of Tx
    checksum offload support provided by some drivers via the hw_enc_features.
    Without this fix enabling GSO means sacrificing Tx checksum offload and
    this actually leads to a performance regression as shown below:
    
                Utilization
                Send
    Throughput  local         GSO
    10^6bits/s  % S           state
      6276.51   8.39          enabled
      7123.52   8.42          disabled
    
    To resolve this it was necessary to address two items.  First
    netif_skb_features needed to be updated so that it would correctly handle
    the Trans Ether Bridging protocol without impacting the need to check for
    Q-in-Q tagging.  To do this it was necessary to update harmonize_features
    so that it used skb_network_protocol instead of just using the outer
    protocol.
    
    Second it was necessary to update the GRE and UDP tunnel segmentation
    offloads so that they would reset the encapsulation bit and inner header
    offsets after the offload was complete.
    
    As a result of this change I have seen the following results on a interface
    with Tx checksum enabled for encapsulated frames:
    
                Utilization
                Send
    Throughput  local         GSO
    10^6bits/s  % S           state
      7123.52   8.42          disabled
      8321.75   5.43          enabled
    
    v2: Instead of replacing refrence to skb->protocol with
        skb_network_protocol just replace the protocol reference in
        harmonize_features to allow for double VLAN tag checks.
    Signed-off-by: default avatarAlexander Duyck <alexander.h.duyck@intel.com>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    cdbaa0bb
dev.c 160 KB