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>
---
 examples/l3fwd/l3fwd_fib.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)
  

> 
> 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>
> ---
>  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@intel.com>

> 2.25.1
  

> -----Original Message-----
> From: Conor Walsh <conor.walsh@intel.com>
> Sent: Tuesday, July 6, 2021 1:06 AM
> To: konstantin.ananyev@intel.com; vladimir.medvedkin@intel.com; Ruifeng
> Wang <Ruifeng.Wang@arm.com>; jerinj@marvell.com
> Cc: dev@dpdk.org; paulis.gributs@intel.com; Conor Walsh
> <conor.walsh@intel.com>
> Subject: [PATCH] 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>
> ---
>  examples/l3fwd/l3fwd_fib.c | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
> 
Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
  

On Mon, Jul 5, 2021 at 7:06 PM Conor Walsh <conor.walsh@intel.com> wrote:
>
> 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.

em can undergo the same change too.
Can you send a followup patch and I would take them both for rc1?

Thanks.

>
> Signed-off-by: Conor Walsh <conor.walsh@intel.com>
  

> > 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.
> 
> em can undergo the same change too.
> Can you send a followup patch and I would take them both for rc1?

Thanks! I will send a patch for em now
/Conor.

> 
> Thanks.
> 
> >
> > Signed-off-by: Conor Walsh <conor.walsh@intel.com>
> 
> --
> David Marchand
  

On Mon, Jul 5, 2021 at 7:06 PM Conor Walsh <conor.walsh@intel.com> wrote:
>
> 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>

Applied, thanks.