rte_eth_tx_burst() always returns 0 in tight loop

[Antonio Di Bacco]

I wonder why calling eth_dev_tx_burst in a tight loop doesn't allow to
write the packets into the transmit buffer. Only solution I found is
to include a small delay after the tx_burst that is less than the
estimated serialization time of the packet in order to be able to
saturate the ethernet line.

Anyway I wonder if this is the right approach.

Thx,
Antonio.

On Sun, Jul 3, 2022 at 10:19 PM Gábor LENCSE <lencse at hit.bme.hu> wrote:
>
> Dear Antonio,
>
> According to my experience, the rte_eth_tx_burst() function reports the
> packets as "sent" (by a non-zero return value), when they are still in
> the transmit buffer.
>
> (If you are interested in the details, you can see them in Section 3.6.5
> of this paper: http://www.hit.bme.hu/~lencse/publications/e104-b_2_128.pdf )
>
> Therefore, I think that the return value of 0 may mean that
> rte_eth_tx_burst() can't even commit itself for the future delivery of
> the packets. I could only guess why. E.g. all its resources have been
> exhausted.
>
> Best regards,
>
> Gábor
>
>
> 7/3/2022 5:57 PM keltezéssel, Antonio Di Bacco írta:
> > I'm trying to send packets continuously in a  tight loop with a burst
> > size of 8 and packets are 9600 bytes long.
> > If I don't insert a delay after the rte_eth_tx_burst it always returns 0.
> >
> > What's the explanation of this behaviour ?
> >
> > Best regards,
> > Antonio.
>