On Wed, 18 Feb 2026 09:48:04 +0100 Morten Brørup <[email protected]> wrote:
> > + * > > + * A return value equal to *nb_pkts* means that all packets have been > > + * consumed, and this is likely to signify that other output packets > > * could be immediately transmitted again. Applications that implement > > a > > * "send as many packets to transmit as possible" policy can check > > this > > * specific case and keep invoking the rte_eth_tx_burst() function > > until > > * a value less than *nb_pkts* is returned. > > * > > + * If a packet cannot be transmitted due to an error (for example, an > > + * invalid offload flag), the driver must still consume it and free > > the > > + * mbuf, rather than stopping at that point. Such packets should be > > + * counted in the *tx_errors* port statistic. > > The above paragraph is driver centric, it should be application centric. Most of the applications are doing it right already since everybody starts with l2fwd, or l3fwd. The problem I see is buggy drivers. > Suggest rephrasing as: > > If a packet cannot be transmitted due to an error (for example, an invalid > offload flag), the rte_eth_tx_burst() function will still consume it, rather > than stopping at that point. > Such packets are counted in the *oerrors* port statistic. > > NB: In struct rte_eth_stats [1], the error counter is named "oerrors", not > "tx_errors". > > [1]: > https://elixir.bootlin.com/dpdk/v25.11/source/lib/ethdev/rte_ethdev.h#L273 Good point, I was thinking of the per-queue stats and xstats. > While discussing details... > Let's say a packet has 4 segments, and the driver only has 2 descriptors > remaining available. > In that case, I think the driver should not consume the packet, but leave it > for the application to either drop it or retry transmitting it later. > Do we want to mention this case too, or is it a semi-obvious case of the > descriptor ring having no more room? There are also other cases of backpressure like when driver talks to kernel and gets EAGAIN or EBUSY
