[PATCH] examples/l3fwd-graph: remove redundant Tx queue limit

[PATCH] examples/l3fwd-graph: remove redundant Tx queue limit

[Sivaprasad Tummala]

In `l3fwd-graph` application, Tx queues are configured per lcore
to enable a lockless design and achieve optimal performance.

The `MAX_TX_QUEUE_PER_PORT` macro, defined as `RTE_MAX_ETHPORTS`,
introduced an artificial constraint on the number of Tx queues
and limited core-scaling performance.

This patch removes the unused `MAX_TX_QUEUE_PER_PORT` macro and
redundant Tx queue check, allowing Tx queues to scale directly
with the no. of lcores.

Fixes: 08bd1a174461 ("examples/l3fwd-graph: add graph-based l3fwd skeleton")
Cc: ndabilpuram@marvell.com
Cc: stable@dpdk.org

Signed-off-by: Sivaprasad Tummala <sivaprasad.tummala@amd.com>
---
 examples/l3fwd-graph/main.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/examples/l3fwd-graph/main.c b/examples/l3fwd-graph/main.c
index 92cdaa1ebe..12908acbba 100644
--- a/examples/l3fwd-graph/main.c
+++ b/examples/l3fwd-graph/main.c
@@ -49,7 +49,6 @@
 #define RX_DESC_DEFAULT 1024
 #define TX_DESC_DEFAULT 1024
 
-#define MAX_TX_QUEUE_PER_PORT RTE_MAX_ETHPORTS
 #define MAX_RX_QUEUE_PER_PORT 128
 
 #define MAX_RX_QUEUE_PER_LCORE 16
@@ -1076,8 +1075,6 @@ main(int argc, char **argv)
 
 		nb_rx_queue = get_port_n_rx_queues(portid);
 		n_tx_queue = nb_lcores;
-		if (n_tx_queue > MAX_TX_QUEUE_PER_PORT)
-			n_tx_queue = MAX_TX_QUEUE_PER_PORT;
 		printf("Creating queues: nb_rxq=%d nb_txq=%u... ",
 		       nb_rx_queue, n_tx_queue);
 
-- 
2.43.0

Re: [PATCH] examples/l3fwd-graph: remove redundant Tx queue limit

[Nithin Dabilpuram]

Acked-by: Nithin Dabilpuram <ndabilpuram@marvell.com>

On Mon, Sep 1, 2025 at 11:39 PM Sivaprasad Tummala
<sivaprasad.tummala@amd.com> wrote:
>
> In `l3fwd-graph` application, Tx queues are configured per lcore
> to enable a lockless design and achieve optimal performance.
>
> The `MAX_TX_QUEUE_PER_PORT` macro, defined as `RTE_MAX_ETHPORTS`,
> introduced an artificial constraint on the number of Tx queues
> and limited core-scaling performance.
>
> This patch removes the unused `MAX_TX_QUEUE_PER_PORT` macro and
> redundant Tx queue check, allowing Tx queues to scale directly
> with the no. of lcores.
>
> Fixes: 08bd1a174461 ("examples/l3fwd-graph: add graph-based l3fwd skeleton")
> Cc: ndabilpuram@marvell.com
> Cc: stable@dpdk.org
>
> Signed-off-by: Sivaprasad Tummala <sivaprasad.tummala@amd.com>
> ---
>  examples/l3fwd-graph/main.c | 3 ---
>  1 file changed, 3 deletions(-)
>
> diff --git a/examples/l3fwd-graph/main.c b/examples/l3fwd-graph/main.c
> index 92cdaa1ebe..12908acbba 100644
> --- a/examples/l3fwd-graph/main.c
> +++ b/examples/l3fwd-graph/main.c
> @@ -49,7 +49,6 @@
>  #define RX_DESC_DEFAULT 1024
>  #define TX_DESC_DEFAULT 1024
>
> -#define MAX_TX_QUEUE_PER_PORT RTE_MAX_ETHPORTS
>  #define MAX_RX_QUEUE_PER_PORT 128
>
>  #define MAX_RX_QUEUE_PER_LCORE 16
> @@ -1076,8 +1075,6 @@ main(int argc, char **argv)
>
>                 nb_rx_queue = get_port_n_rx_queues(portid);
>                 n_tx_queue = nb_lcores;
> -               if (n_tx_queue > MAX_TX_QUEUE_PER_PORT)
> -                       n_tx_queue = MAX_TX_QUEUE_PER_PORT;
>                 printf("Creating queues: nb_rxq=%d nb_txq=%u... ",
>                        nb_rx_queue, n_tx_queue);
>
> --
> 2.43.0
>

RE: [PATCH] examples/l3fwd-graph: remove redundant Tx queue limit

[Konstantin Ananyev]

> On Mon, Sep 1, 2025 at 11:39 PM Sivaprasad Tummala
> <sivaprasad.tummala@amd.com> wrote:
> >
> > In `l3fwd-graph` application, Tx queues are configured per lcore
> > to enable a lockless design and achieve optimal performance.
> >
> > The `MAX_TX_QUEUE_PER_PORT` macro, defined as `RTE_MAX_ETHPORTS`,
> > introduced an artificial constraint on the number of Tx queues
> > and limited core-scaling performance.
> >
> > This patch removes the unused `MAX_TX_QUEUE_PER_PORT` macro and
> > redundant Tx queue check, allowing Tx queues to scale directly
> > with the no. of lcores.
> >
> > Fixes: 08bd1a174461 ("examples/l3fwd-graph: add graph-based l3fwd skeleton")
> > Cc: ndabilpuram@marvell.com
> > Cc: stable@dpdk.org
> >
> > Signed-off-by: Sivaprasad Tummala <sivaprasad.tummala@amd.com>
> > ---
> >  examples/l3fwd-graph/main.c | 3 ---
> >  1 file changed, 3 deletions(-)
> >
> > diff --git a/examples/l3fwd-graph/main.c b/examples/l3fwd-graph/main.c
> > index 92cdaa1ebe..12908acbba 100644
> > --- a/examples/l3fwd-graph/main.c
> > +++ b/examples/l3fwd-graph/main.c
> > @@ -49,7 +49,6 @@
> >  #define RX_DESC_DEFAULT 1024
> >  #define TX_DESC_DEFAULT 1024
> >
> > -#define MAX_TX_QUEUE_PER_PORT RTE_MAX_ETHPORTS
> >  #define MAX_RX_QUEUE_PER_PORT 128

AFAIK, in the mainline we actually have:
#define MAX_TX_QUEUE_PER_PORT RTE_MAX_LCORE

since:
commit 88256ed85338c572d73006e4c4530a52d3b477ff
Author: Harman Kalra <hkalra@marvell.com>
Date:   Tue Jan 12 23:54:46 2021 +0530

    examples/l3fwd: remove limitation on Tx queue count

What I am missing here?

> >
> >  #define MAX_RX_QUEUE_PER_LCORE 16
> > @@ -1076,8 +1075,6 @@ main(int argc, char **argv)
> >
> >                 nb_rx_queue = get_port_n_rx_queues(portid);
> >                 n_tx_queue = nb_lcores;
> > -               if (n_tx_queue > MAX_TX_QUEUE_PER_PORT)
> > -                       n_tx_queue = MAX_TX_QUEUE_PER_PORT;
> >                 printf("Creating queues: nb_rxq=%d nb_txq=%u... ",
> >                        nb_rx_queue, n_tx_queue);
> >
> > --
> > 2.43.0
> >