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    udp: use a separate rx queue for packet reception · 2276f58a
    Paolo Abeni 提交于
    under udp flood the sk_receive_queue spinlock is heavily contended.
    This patch try to reduce the contention on such lock adding a
    second receive queue to the udp sockets; recvmsg() looks first
    in such queue and, only if empty, tries to fetch the data from
    sk_receive_queue. The latter is spliced into the newly added
    queue every time the receive path has to acquire the
    sk_receive_queue lock.
    
    The accounting of forward allocated memory is still protected with
    the sk_receive_queue lock, so udp_rmem_release() needs to acquire
    both locks when the forward deficit is flushed.
    
    On specific scenarios we can end up acquiring and releasing the
    sk_receive_queue lock multiple times; that will be covered by
    the next patch
    Suggested-by: NEric Dumazet <edumazet@google.com>
    Signed-off-by: NPaolo Abeni <pabeni@redhat.com>
    Acked-by: NEric Dumazet <edumazet@google.com>
    Signed-off-by: NDavid S. Miller <davem@davemloft.net>
    2276f58a
udp.c 38.9 KB