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

["Tummala, Sivaprasad" <Sivaprasad.Tummala@amd.com>]

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[AMD Official Use Only - AMD Internal Distribution Only]

Hi Konstantin,

________________________________
From: Konstantin Ananyev <konstantin.ananyev@huawei.com>
Sent: Monday, September 22, 2025 12:19 PM
To: Nithin Dabilpuram <nithind1988@gmail.com>; Tummala, Sivaprasad <Sivaprasad.Tummala@amd.com>
Cc: jerinj@marvell.com <jerinj@marvell.com>; kirankumark@marvell.com <kirankumark@marvell.com>; ndabilpuram@marvell.com <ndabilpuram@marvell.com>; yanzhirun_163@163.com <yanzhirun_163@163.com>; david.marchand@redhat.com <david.marchand@redhat.com>; ktraynor@redhat.com <ktraynor@redhat.com>; thomas@monjalon.net <thomas@monjalon.net>; konstantin.v.ananyev@yandex.ru <konstantin.v.ananyev@yandex.ru>; bruce.richardson@intel.com <bruce.richardson@intel.com>; maxime.coquelin@redhat.com <maxime.coquelin@redhat.com>; aconole@redhat.com <aconole@redhat.com>; dev@dpdk.org <dev@dpdk.org>; stable@dpdk.org <stable@dpdk.org>
Subject: RE: [PATCH] examples/l3fwd-graph: remove redundant Tx queue limit

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> > 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
>
In l3fwd-graph app, this change is not available and instead we have
#define MAX_TX_QUEUE_PER_PORT RTE_MAX_ETHPORTS

> 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?
This patch marked here was fixing l3fwd app and not l3fwd-graph

>
> > >
> > >  #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
> > >

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