• Michael S. Tsirkin's avatar
    vhost-net: select tx zero copy dynamically · eaae8132
    Michael S. Tsirkin authored
    Even when vhost-net is in zero-copy transmit mode,
    net core might still decide to copy the skb later
    which is somewhat slower than a copy in user
    context: data copy overhead is added to the cost of
    page pin/unpin. The result is that enabling tx zero copy
    option leads to higher CPU utilization for guest to guest
    and guest to host traffic.
    
    To fix this, suppress zero copy tx after a given number of
    packets triggered late data copy. Re-enable periodically
    to detect workload changes.
    Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    eaae8132
net.c 24.1 KB