• E
    net: less interrupt masking in NAPI · d75b1ade
    Eric Dumazet 提交于
    net_rx_action() can mask irqs a single time to transfert sd->poll_list
    into a private list, for a very short duration.
    
    Then, napi_complete() can avoid masking irqs again,
    and net_rx_action() only needs to mask irq again in slow path.
    
    This patch removes 2 couples of irq mask/unmask per typical NAPI run,
    more if multiple napi were triggered.
    
    Note this also allows to give control back to caller (do_softirq())
    more often, so that other softirq handlers can be called a bit earlier,
    or ksoftirqd can be wakeup earlier under pressure.
    
    This was developed while testing an alternative to RX interrupt
    mitigation to reduce latencies while keeping or improving GRO
    aggregation on fast NIC.
    
    Idea is to test napi->gro_list at the end of a napi->poll() and
    reschedule one NAPI poll, but after servicing a full round of
    softirqs (timers, TX, rcu, ...). This will be allowed only if softirq
    is currently serviced by idle task or ksoftirqd, and resched not needed.
    Signed-off-by: NEric Dumazet <edumazet@google.com>
    Cc: Willem de Bruijn <willemb@google.com>
    Signed-off-by: NDavid S. Miller <davem@davemloft.net>
    d75b1ade
dev.c 183.0 KB