examples/l3fwd: remove useless reloads in FIB main loop

This patch aligns the l3fwd FIB 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>
Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
Reviewed-by: David Marchand <david.marchand@redhat.com>

diff --git a/examples/l3fwd/l3fwd_fib.c b/examples/l3fwd/l3fwd_fib.c
index 178722994284cf57884aca93c833cc15a0110c3c..d083ddfdd5c4b03d4301e13eb685aa876c416dd2 100644 (file)
--- a/examples/l3fwd/l3fwd_fib.c
+++ b/examples/l3fwd/l3fwd_fib.c
@@ -182,14 +182,16 @@ fib_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;
@@ -207,7 +209,7 @@ fib_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;
@@ -221,7 +223,7 @@ fib_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,