Function rte_red_enqueue_empty

dpdk/lib/sched/rte_red.h:195–231

* @brief Updates queue average in condition when queue is empty * * Note: packet is never dropped in this particular case. * * @param red_cfg [in] config pointer to a RED configuration parameter structure * @param red [in,out] data pointer to RED runtime data * @param time [in] current time stamp * * @return Operation status * @retval 0 enqueue the packet * @retval 1 drop the packet base

 * @retval 2 drop the packet based on mark probability criterion
 */
static inline int
rte_red_enqueue_empty(const struct rte_red_config *red_cfg,
	struct rte_red *red,
	const uint64_t time)
{
	uint64_t time_diff = 0, m = 0;

	RTE_ASSERT(red_cfg != NULL);
	RTE_ASSERT(red != NULL);

	red->count ++;

	/**
	 * We compute avg but we don't compare avg against
	 *  min_th or max_th, nor calculate drop probability
	 */
	time_diff = time - red->q_time;

	/**
	 * m is the number of packets that might have arrived while the queue was empty.
	 * In this case we have time stamps provided by scheduler in byte units (bytes
	 * transmitted on network port). Such time stamp translates into time units as
	 * port speed is fixed but such approach simplifies the code.
	 */
	m = time_diff / RTE_RED_S;

	/**
	 * Check that m will fit into 16-bit unsigned integer
	 */
	if (m >= RTE_RED_2POW16) {
		red->avg = 0;
	} else {
		red->avg = (red->avg >> RTE_RED_SCALING) * __rte_red_calc_qempty_factor(red_cfg->wq_log2, (uint16_t) m);
	}

	return 0;
}

/**
 *  Drop probability (Sally Floyd and Van Jacobson):