lib/net: review the size of mbuf pools

This commit fixes two miscalculations in the size of mbuf pools:

1. calculate_mempool_config_para() was not accounting for
multiple members in bonded interfaces; and

2. Although unlikely, a GK or GT instance might receive all
the packets, so the instances must account for this worst case.

gk/main.c

@@ -2541,9 +2541,13 @@ gk_stage1(void *arg)
 
 	num_mbuf = calculate_mempool_config_para("gk", gk_conf->net,
 		gk_conf->front_max_pkt_burst + gk_conf->back_max_pkt_burst +
+		/*
+		 * One cannot divide the sum below per gk_conf->num_lcores
+		 * because, though unlikely, it might happen that
+		 * all packets go to a single instance.
+		 */
 		(gk_conf->net->front.total_pkt_burst +
-		gk_conf->net->back.total_pkt_burst + gk_conf->num_lcores - 1) /
-		gk_conf->num_lcores);
+		gk_conf->net->back.total_pkt_burst));
 
 	sol_conf = gk_conf->sol_conf;
 	for (i = 0; i < gk_conf->num_lcores; i++) {

gt/main.c

@@ -2067,8 +2067,12 @@ init_gt_instances(struct gt_config *gt_conf)
 		gt_conf->net, gt_conf->max_pkt_burst +
 		gt_conf->frag_max_entries + gt_conf->max_pkt_burst +
 		gt_conf->max_ggu_notify_pkts +
-		(gt_conf->net->front.total_pkt_burst +
-		gt_conf->num_lcores - 1) / gt_conf->num_lcores);
+		/*
+		 * One cannot divide the sum below per gt_conf->num_lcores
+		 * because, though unlikely, it might happen that
+		 * all packets go to a single instance.
+		 */
+		gt_conf->net->front.total_pkt_burst);
 
 	/* Set up queue identifiers now for RSS, before instances start. */
 	for (i = 0; i < gt_conf->num_lcores; i++) {

lib/net.c

@@ -2234,25 +2234,42 @@ start_iface(struct gatekeeper_if *iface)
 	return ret;
 }
 
+static inline uint32_t
+if_rx_desc(const struct gatekeeper_if *iface)
+{
+	return (uint32_t)iface->num_ports * iface->num_rx_desc;
+}
+
+static inline uint32_t
+if_tx_desc(const struct gatekeeper_if *iface)
+{
+	return (uint32_t)iface->num_ports * iface->num_tx_desc;
+}
+
 unsigned int
 calculate_mempool_config_para(const char *block_name,
 	struct net_config *net_conf, unsigned int total_pkt_burst)
 {
-	unsigned int num_mbuf;
-
 	/*
-	 * The total number of receive descriptors to
-	 * allocate per lcore for the receive ring over all interfaces.
+	 * The total number of receive descriptors to allocate per lcore
+	 * for the receive ring of the front interface.
 	 */
-	uint16_t total_rx_desc = net_conf->front.num_rx_desc +
-		(net_conf->back_iface_enabled ? net_conf->back.num_rx_desc : 0);
+	uint32_t total_rx_desc = if_rx_desc(&net_conf->front);
 
 	/*
-	 * The total number of transmit descriptors to
-	 * allocate per lcore for the transmit ring over all interfaces.
+	 * The total number of transmit descriptors to allocate per lcore
+	 * for the transmit ring of the front interface.
 	 */
-	uint16_t total_tx_desc = net_conf->front.num_tx_desc +
-		(net_conf->back_iface_enabled ? net_conf->back.num_tx_desc : 0);
+	uint32_t total_tx_desc = if_tx_desc(&net_conf->front);
+
+	uint32_t max_num_pkt;
+	unsigned int num_mbuf;
+
+	if (net_conf->back_iface_enabled) {
+		/* Account for the back interface. */
+		total_rx_desc += if_rx_desc(&net_conf->back);
+		total_tx_desc += if_tx_desc(&net_conf->back);
+	}
 
 	/*
 	 * The number of elements in the mbuf pool.
@@ -2261,16 +2278,16 @@ calculate_mempool_config_para(const char *block_name,
 	 * It's the number of RX descriptors, the number of TX descriptors,
 	 * and the number of packet burst buffers.
 	 */
-	uint32_t max_num_pkt = total_rx_desc + total_tx_desc + total_pkt_burst;
+	max_num_pkt = total_rx_desc + total_tx_desc + total_pkt_burst;
 
 	/*
 	 * The optimum size (in terms of memory usage) for a mempool is when
 	 * it is a power of two minus one.
 	 */
 	num_mbuf = rte_align32pow2(max_num_pkt) - 1;
 
-	G_LOG(NOTICE, "%s: %s: total_pkt_burst = %hu packets, total_rx_desc = %hu descriptors, total_tx_desc = %hu descriptors, max_num_pkt = %u packets, num_mbuf = %u packets.\n",
-		block_name, __func__, total_pkt_burst, total_rx_desc,
+	G_LOG(NOTICE, "%s(%s): total_pkt_burst = %u packets, total_rx_desc = %u descriptors, total_tx_desc = %u descriptors, max_num_pkt = %u packets, num_mbuf = %u packets\n",
+		__func__, block_name, total_pkt_burst, total_rx_desc,
 		total_tx_desc, max_num_pkt, num_mbuf);
 
 	return num_mbuf;