• David Arinzon's avatar
    net: ena: Update NUMA TPH hint register upon NUMA node update · a8ee104f
    David Arinzon authored
    The device supports a PCIe optimization hint, which indicates on
    which NUMA the queue is currently processed. This hint is utilized
    by PCIe in order to reduce its access time by accessing the
    correct NUMA resources and maintaining cache coherence.
    
    The driver calls the register update for the hint (called TPH -
    TLP Processing Hint) during the NAPI loop.
    
    Though the update is expected upon a NUMA change (when a queue
    is moved from one NUMA to the other), the current logic performs
    a register update when the queue is moved to a different CPU,
    but the CPU is not necessarily in a different NUMA.
    
    The changes include:
    1. Performing the TPH update only when the queue has switched
    a NUMA node.
    2. Moving the TPH update call to be triggered only when NAPI was
    scheduled from interrupt context, as opposed to a busy-polling loop.
    This is due to the fact that during busy-polling, the frequency
    of CPU switches for a particular queue is significantly higher,
    thus, the likelihood to switch NUMA is much higher. Therefore,
    providing the frequent updates to the device upon a NUMA update
    are unlikely to be beneficial.
    
    Fixes: 1738cd3e ("net: ena: Add a driver for Amazon Elastic Network Adapters (ENA)")
    Signed-off-by: default avatarDavid Arinzon <darinzon@amazon.com>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    a8ee104f
ena_netdev.h 10.7 KB