Re: nfnetlink_queue -- why linear lookup ?

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On 8/14/21 11:01 PM, Florian Westphal wrote:
alexandre.ferrieux@xxxxxxxxxx <alexandre.ferrieux@xxxxxxxxxx> wrote:
  find_dequeue_entry(struct nfqnl_instance *queue, unsigned int id)
    list_for_each_entry(i, &queue->queue_list, list) {
      if (i->id == id) {
        entry = i;

As a result, in a situation of "highly asynchronous" verdicts, i.e. when we
want some packets to linger in the queue for some time before reinjection,
the mere existence of a large number of such "old packets" may incur a
nonnegligible cost to the system.

So I'm wondering: why is the list implemented as a simple linked list
instead of an array directly indexed by the id (like file descriptors) ?

Because when this was implemented "highly asynchronous" was not on the
radar.  All users of this (that I know of) do in-order verdicts.

So, O(N) instead of O(1) just because "I currently can't imagine N>5" ?

Would a patch to that effect be rejected ?


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