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  1. Sep 01, 2017
    • Cong Wang's avatar
      net_sched: add reverse binding for tc class · 07d79fc7
      Cong Wang authored
      
      
      TC filters when used as classifiers are bound to TC classes.
      However, there is a hidden difference when adding them in different
      orders:
      
      1. If we add tc classes before its filters, everything is fine.
         Logically, the classes exist before we specify their ID's in
         filters, it is easy to bind them together, just as in the current
         code base.
      
      2. If we add tc filters before the tc classes they bind, we have to
         do dynamic lookup in fast path. What's worse, this happens all
         the time not just once, because on fast path tcf_result is passed
         on stack, there is no way to propagate back to the one in tc filters.
      
      This hidden difference hurts performance silently if we have many tc
      classes in hierarchy.
      
      This patch intends to close this gap by doing the reverse binding when
      we create a new class, in this case we can actually search all the
      filters in its parent, match and fixup by classid. And because
      tcf_result is specific to each type of tc filter, we have to introduce
      a new ops for each filter to tell how to bind the class.
      
      Note, we still can NOT totally get rid of those class lookup in
      ->enqueue() because cgroup and flow filters have no way to determine
      the classid at setup time, they still have to go through dynamic lookup.
      
      Cc: Jamal Hadi Salim <jhs@mojatatu.com>
      Signed-off-by: default avatarCong Wang <xiyou.wangcong@gmail.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      07d79fc7
  2. Aug 31, 2017
  3. Aug 30, 2017