• Julian Wiedmann's avatar
    s390/qeth: add TX multiqueue support for IQD devices · 3a18d754
    Julian Wiedmann authored
    qeth has been supporting multiple HW Output Queues for a long time. But
    rather than exposing those queues to the stack, it uses its own queue
    selection logic in .ndo_start_xmit... with all the drawbacks that
    entails.
    Start off by switching IQD devices over to a proper mqs net_device,
    and converting all the netdev_queue management code.
    
    One oddity with IQD devices is the requirement to place all mcast
    traffic on the _highest_ established HW queue. Doing so via
    .ndo_select_queue seems straight-forward - but that won't work if only
    some of the HW queues are active
    (ie. when dev->real_num_tx_queues < dev->num_tx_queues), since
    netdev_cap_txqueue() will not allow us to put skbs on the higher queues.
    
    To make this work, we
    1. let .ndo_select_queue() map all mcast traffic to netdev_queue 0, and
    2. later re-map the netdev_queue and HW queue indices in
       .ndo_start_xmit and the TX completion handler.
    
    With this patch we default to a fixed set of 1 ucast and 1 mcast queue.
    Support for dynamic reconfiguration is added at a later time.
    Signed-off-by: default avatarJulian Wiedmann <jwi@linux.ibm.com>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    3a18d754
qeth_l2_main.c 58.8 KB