diff mbox series

[v3,2/2] examples/l3fwd: eliminate unnecessary reloads in loop

Message ID 20210610065740.231799-3-ruifeng.wang@arm.com (mailing list archive)
State Accepted, archived
Delegated to: David Marchand
Headers
Series l3fwd improvements |

Checks

Context Check Description
ci/checkpatch success coding style OK
ci/Intel-compilation success Compilation OK
ci/intel-Testing success Testing PASS
ci/github-robot success github build: passed
ci/iol-intel-Functional fail Functional Testing issues
ci/iol-abi-testing success Testing PASS
ci/iol-testing success Testing PASS
ci/iol-intel-Performance success Performance Testing PASS

Commit Message

Ruifeng Wang June 10, 2021, 6:57 a.m. UTC 
  Number of rx queue and number of rx port in lcore config are constants
during the period of l3 forward application running. But compiler has
no this information.

Copied values from lcore config to local variables and used the local
variables for iteration. Compiler can see that the local variables are
not changed, so qconf reloads at each iteration can be eliminated.

The change showed 1.8% performance uplift in single core, single port,
single queue test on N1SDP platform with MLX5 NIC.

Signed-off-by: Ruifeng Wang <ruifeng.wang@arm.com>
Acked-by: Jerin Jacob <jerinj@marvell.com>
---
 examples/l3fwd/l3fwd_lpm.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)
diff mbox series

Patch

diff --git a/examples/l3fwd/l3fwd_lpm.c b/examples/l3fwd/l3fwd_lpm.c
index 427c72b1d2..ff1c18a442 100644
--- a/examples/l3fwd/l3fwd_lpm.c
+++ b/examples/l3fwd/l3fwd_lpm.c
@@ -154,14 +154,16 @@  lpm_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;
@@ -181,7 +183,7 @@  lpm_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;
@@ -197,7 +199,7 @@  lpm_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,