reuse the packets after tx burst

[Lokesh Chakka]

hi stephen,

Thanks for your response. However it seems the solution is not working. The
following is the modified snippet....

while( condition )
{
     for( pkt_count=0; pkt_count<num_of_pkts_per_queue; pkt_count++ )
     {
          rte_mbuf_refcnt_set( mbuf[pkt_count], 2 );// setting to two -
first and second iteration
     }
     for( pkt_count=0; pkt_count<5; pkt_count++ )
     {
          fprintf( stderr, "%s %d %u\n", __func__, __LINE__,
rte_mbuf_refcnt_read( mbuf[pkt_count] ) );//able to print two- first and
second iteration
     }
     if( rte_eth_tx_burst( port_id, 0, mbuf, num_of_pkts_per_queue ) !=
num_of_pkts_per_queue )
     {
          fprintf( stderr, "%s %d %d %s\n", __func__, __LINE__, rte_errno,
rte_strerror(rte_errno) );//failing second time
          rte_exit( EXIT_FAILURE, "%s %d rte_eth_tx_burst port id: %u\n",
__func__, __LINE__, port_id );
     }
     fprintf( stderr, "%s %d port: %u sent %u packets\n", __func__,
__LINE__, port_id, num_of_pkts_per_queue );//able to send once - first
iteration only
     for( pkt_count=0; pkt_count<5; pkt_count++ )
     {
          fprintf( stderr, "%s %d %u\n", __func__, __LINE__,
rte_mbuf_refcnt_read( mbuf[pkt_count] ) );//refcnt is printing one
     }
}

There seems to be some more gap in my understanding. Could you please help
understand the issue?

Thanks & Regards
--
Lokesh Chakka.


On Mon, Aug 12, 2024 at 8:22 PM Stephen Hemminger <
stephen at networkplumber.org> wrote:

> On Mon, 12 Aug 2024 15:55:50 +0530
> Lokesh Chakka <lvenkatakumarchakka at gmail.com> wrote:
>
> > hello,
> >
> > Here is a small piece of code :
> >
> > while( condition )
> > {
> >
> >       if( rte_eth_tx_burst( port_id, 0, mbuf, num_of_pkts_per_queue ) !=
> > num_of_pkts_per_queue )
> >       {
> >               fprintf( stderr, "%d %s\n", rte_errno,
> rte_strerror(rte_errno) );
> >               rte_exit( EXIT_FAILURE, "%s %d rte_eth_tx_burst port id:
> %u\n",
> > __func__, __LINE__, port_id );//second iteration failing.
> >       }
> >       fprintf( stderr, "%s %d port: %u packet: %c sent %u packets\n",
> > __func__, __LINE__, port_id, argv[3][0], num_of_pkts_per_queue
> > );//printing once
> >       for( pkt_count=0; pkt_count<num_of_pkts_per_queue; pkt_count++ )
> >       {//want to send same data again...!!!
> >               mbuf[pkt_count]->pkt_len = mbuf[pkt_count]->data_len =
> dev_info.max_mtu;
> >
> >       }
> >
> > }
> >
> > Can someone help me understand how to reuse the packets again to send the
> > same data ?
> >
>
> When packet is passed to tx_burst, the ownership of that mbuf is passed
> to the driver. The driver will free it after it is sent.
>
> One option would be to increase the reference count on the packet before
> sending.
> Using rte_mbuf_refcnt_update() function to add one to refcount.
> Then the driver will decrement refcount and the refcount will still be one
> (not freed).
>
> Assume this is some kind of packet generator.
>
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