• Daniel Borkmann's avatar
    net: sched: further simplify handle_ing · d2788d34
    Daniel Borkmann authored
    Ingress qdisc has no other purpose than calling into tc_classify()
    that executes attached classifier(s) and action(s).
    
    It has a 1:1 relationship to dev->ingress_queue. After having commit
    087c1a60 ("net: sched: run ingress qdisc without locks") removed
    the central ingress lock, one major contention point is gone.
    
    The extra indirection layers however, are not necessary for calling
    into ingress qdisc. pktgen calling locally into netif_receive_skb()
    with a dummy u32, single CPU result on a Supermicro X10SLM-F, Xeon
    E3-1240: before ~21,1 Mpps, after patch ~22,9 Mpps.
    
    We can redirect the private classifier list to the netdev directly,
    without changing any classifier API bits (!) and execute on that from
    handle_ing() side. The __QDISC_STATE_DEACTIVATE test can be removed,
    ingress qdisc doesn't have a queue and thus dev_deactivate_queue()
    is also not applicable, ingress_cl_list provides similar behaviour.
    In other words, ingress qdisc acts like TCQ_F_BUILTIN qdisc.
    
    One next possible step is the removal of the dev's ingress (dummy)
    netdev_queue, and to only have the list member in the netdevice
    itself.
    
    Note, the filter chain is RCU protected and individual filter elements
    are being kfree'd by sched subsystem after RCU grace period. RCU read
    lock is being held by __netif_receive_skb_core().
    
    Joint work with Alexei Starovoitov.
    Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
    Signed-off-by: default avatarAlexei Starovoitov <ast@plumgrid.com>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    d2788d34
dev.c 186 KB