Eric Lee / smarc-fsl-linux-kernel

18 Jan, 2011

1 commit

23 Jul, 2010

1 commit

  • e8648a1fd   netfilter: add xt_cpu match ... Browse Code »

    In some situations a CPU match permits a better spreading of
    connections, or select targets only for a given cpu.

    With Remote Packet Steering or multiqueue NIC and appropriate IRQ
    affinities, we can distribute trafic on available cpus, per session.
    (all RX packets for a given flow is handled by a given cpu)

    Some legacy applications being not SMP friendly, one way to scale a
    server is to run multiple copies of them.

    Instead of randomly choosing an instance, we can use the cpu number as a
    key so that softirq handler for a whole instance is running on a single
    cpu, maximizing cache effects in TCP/UDP stacks.

    Using NAT for example, a four ways machine might run four copies of
    server application, using a separate listening port for each instance,
    but still presenting an unique external port :

    iptables -t nat -A PREROUTING -p tcp --dport 80 -m cpu --cpu 0 \
    -j REDIRECT --to-port 8080

    iptables -t nat -A PREROUTING -p tcp --dport 80 -m cpu --cpu 1 \
    -j REDIRECT --to-port 8081

    iptables -t nat -A PREROUTING -p tcp --dport 80 -m cpu --cpu 2 \
    -j REDIRECT --to-port 8082

    iptables -t nat -A PREROUTING -p tcp --dport 80 -m cpu --cpu 3 \
    -j REDIRECT --to-port 8083

    Signed-off-by: Eric Dumazet
    Signed-off-by: Patrick McHardy

    Eric Dumazet