Skip to content
  • Eric Dumazet's avatar
    net: introduce SO_INCOMING_CPU · 2c8c56e1
    Eric Dumazet authored
    Alternative to RPS/RFS is to use hardware support for multiple
    Then split a set of million of sockets into worker threads, each
    one using epoll() to manage events on its own socket pool.
    Ideally, we want one thread per RX/TX queue/cpu, but we have no way to
    know after accept() or connect() on which queue/cpu a socket is managed.
    We normally use one cpu per RX queue (IRQ smp_affinity being properly
    set), so remembering on socket structure which cpu delivered last packet
    is enough to solve the problem.
    After accept(), connect(), or even file descriptor passing around
    processes, applications can use :
     int cpu;
     socklen_t len = sizeof(cpu);
     getsockopt(fd, SOL_SOCKET, SO_INCOMING_CPU, &cpu, &len);
    And use this information to put the socket into the right silo
    for optimal performance, as all networking stack should run
    on the appropriate cpu, without need to send IPI (RPS/RFS).
    Signed-off-by: default avatarEric Dumazet <>
    Signed-off-by: default avatarDavid S. Miller <>