[dpdk-dev] [PATCH] examples/l3fwd: remove useless reloads in EM main loop

[Conor Walsh]

This patch aligns the l3fwd EM code with the changes made to LPM in
commit 74fb854a3de6 ("examples/l3fwd: remove useless reloads in LPM
main loop").
This change ensures the compiler knows that the lcore config variables
are constant values and the compiler will then optimize the code
accordingly.

Signed-off-by: Conor Walsh <conor.walsh at intel.com>
---
 examples/l3fwd/l3fwd_em.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/examples/l3fwd/l3fwd_em.c b/examples/l3fwd/l3fwd_em.c
index 01f8dff485..43fc7612e7 100644
--- a/examples/l3fwd/l3fwd_em.c
+++ b/examples/l3fwd/l3fwd_em.c
@@ -632,14 +632,16 @@ em_main_loop(__rte_unused void *dummy)
 	lcore_id = rte_lcore_id();
 	qconf = &lcore_conf[lcore_id];
 
-	if (qconf->n_rx_queue == 0) {
+	const uint16_t n_rx_q = qconf->n_rx_queue;
+	const uint16_t n_tx_p = qconf->n_tx_port;
+	if (n_rx_q == 0) {
 		RTE_LOG(INFO, L3FWD, "lcore %u has nothing to do\n", lcore_id);
 		return 0;
 	}
 
 	RTE_LOG(INFO, L3FWD, "entering main loop on lcore %u\n", lcore_id);
 
-	for (i = 0; i < qconf->n_rx_queue; i++) {
+	for (i = 0; i < n_rx_q; i++) {
 
 		portid = qconf->rx_queue_list[i].port_id;
 		queueid = qconf->rx_queue_list[i].queue_id;
@@ -659,7 +661,7 @@ em_main_loop(__rte_unused void *dummy)
 		diff_tsc = cur_tsc - prev_tsc;
 		if (unlikely(diff_tsc > drain_tsc)) {
 
-			for (i = 0; i < qconf->n_tx_port; ++i) {
+			for (i = 0; i < n_tx_p; ++i) {
 				portid = qconf->tx_port_id[i];
 				if (qconf->tx_mbufs[portid].len == 0)
 					continue;
@@ -675,7 +677,7 @@ em_main_loop(__rte_unused void *dummy)
 		/*
 		 * Read packet from RX queues
 		 */
-		for (i = 0; i < qconf->n_rx_queue; ++i) {
+		for (i = 0; i < n_rx_q; ++i) {
 			portid = qconf->rx_queue_list[i].port_id;
 			queueid = qconf->rx_queue_list[i].queue_id;
 			nb_rx = rte_eth_rx_burst(portid, queueid, pkts_burst,
-- 
2.25.1