examples/l3fwd: remove useless reloads in EM main loop

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@intel.com>
Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
Reviewed-by: David Marchand <david.marchand@redhat.com>

diff --git a/examples/l3fwd/l3fwd_em.c b/examples/l3fwd/l3fwd_em.c
index 01f8dff48539b38c83c7fc05d2cd92e42c53b9c8..43fc7612e74f6bcc392359d5616d17c8a59acc0e 100644 (file)
--- 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,