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

[Ananyev, Konstantin]

> 
> 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 at intel.com>
> ---
>  examples/l3fwd/l3fwd_fib.c | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/examples/l3fwd/l3fwd_fib.c b/examples/l3fwd/l3fwd_fib.c
> index 1787229942..d083ddfdd5 100644
> --- 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,
> --

Acked-by: Konstantin Ananyev <konstantin.ananyev at intel.com>

> 2.25.1