Method RunTask

core/modules/queue.cc:159–201

to downstream */

/* to downstream */
struct task_result Queue::RunTask(Context *ctx, bess::PacketBatch *batch,
                                  void *) {
  if (children_overload_ > 0) {
    return {
        .block = true, .packets = 0, .bits = 0,
    };
  }

  const int burst = ACCESS_ONCE(burst_);
  const int pkt_overhead = 24;

  uint64_t total_bytes = 0;

  uint32_t cnt = llring_sc_dequeue_burst(queue_, (void **)batch->pkts(), burst);

  if (cnt == 0) {
    return {.block = true, .packets = 0, .bits = 0};
  }

  stats_.dequeued += cnt;
  batch->set_cnt(cnt);

  if (prefetch_) {
    for (uint32_t i = 0; i < cnt; i++) {
      total_bytes += batch->pkts()[i]->total_len();
      rte_prefetch0(batch->pkts()[i]->head_data());
    }
  } else {
    for (uint32_t i = 0; i < cnt; i++) {
      total_bytes += batch->pkts()[i]->total_len();
    }
  }

  RunNextModule(ctx, batch);

  if (backpressure_ && llring_count(queue_) < low_water_) {
    SignalUnderload();
  }

  return {.block = false,
          .packets = cnt,
          .bits = (total_bytes + cnt * pkt_overhead) * 8};
}

CommandResponse Queue::CommandSetBurst(
    const bess::pb::QueueCommandSetBurstArg &arg) {