igb网卡驱动
do_IRQ -->handle_irq -->generic_handle_irq_desc -->handle_edge_irq --> handle_irq_event -->igb_msix_ring -->napi_schedule -->list_add_tail
__do_softirq -->net_rx_action -->napi_poll -->igb_poll -->igb_clean_rx_irq-->napi_gro_receive -->napi_skb_finish -->netif_receive_skb_internal
--> __netif_receive_skb_core -->deliver_skb
内核参数 threadirqs 设置启动softirqd