RE: [PATCH v7 2/3] pcap: support MTU set for linux interfaces TX enhancment

[Ido Goshen <Ido@cgstowernetworks.com>]

> -----Original Message-----
> From: Stephen Hemminger <stephen@networkplumber.org>
> Sent: Tuesday, 21 June 2022 1:53
> To: Ido Goshen <Ido@cgstowernetworks.com>
> Cc: ferruh.yigit@xilinx.com; dev@dpdk.org
> Subject: Re: [PATCH v7 2/3] pcap: support MTU set for linux interfaces TX
> enhancment
> 
> On Sun, 19 Jun 2022 12:30:33 +0300
> Ido Goshen <ido@cgstowernetworks.com> wrote:
> 
> > Drop only the oversized packets and not its entrie burst mbuf will be
> > freed and will be counted as oerror
> >
> > Signed-off-by: Ido Goshen <ido@cgstowernetworks.com>
> > ---
> >  drivers/net/pcap/pcap_ethdev.c | 10 ++++++++--
> >  1 file changed, 8 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/net/pcap/pcap_ethdev.c
> > b/drivers/net/pcap/pcap_ethdev.c index 2221c53051..ff98762058 100644
> > --- a/drivers/net/pcap/pcap_ethdev.c
> > +++ b/drivers/net/pcap/pcap_ethdev.c
> > @@ -494,8 +494,14 @@ eth_pcap_tx(void *queue, struct rte_mbuf **bufs,
> uint16_t nb_pkts)
> >  		 */
> >  		ret = pcap_sendpacket(pcap,
> >  			rte_pktmbuf_read(mbuf, 0, len, temp_data), len);
> > -		if (unlikely(ret != 0))
> > -			break;
> > +		if (unlikely(ret != 0)) {
> > +			if (errno == EMSGSIZE) {
> 
> Will this show up in tx_errors?
>

[idog] yes
It will be counted few lines below by
	'dumper_q->tx_stat.err_pkts += nb_pkts - num_tx;'
as this case doesn't increment the 'num_tx'

test example:

build/app/dpdk-testpmd --no-huge -m1024 -l 0-2  --vdev='net_pcap0,iface=veth0' --vdev='net_pcap1,iface=veth1' -- -i
...
testpmd> port config mtu 0 9400
testpmd> port config mtu 1 1500
testpmd> start
...
testpmd> stop
Telling cores to stop...
Waiting for lcores to finish...

  ---------------------- Forward statistics for port 0  ----------------------
  RX-packets: 1              RX-dropped: 0             RX-total: 1
  TX-packets: 0              TX-dropped: 0             TX-total: 0
  ----------------------------------------------------------------------------

  ---------------------- Forward statistics for port 1  ----------------------
  RX-packets: 0              RX-dropped: 0             RX-total: 0
  TX-packets: 0              TX-dropped: 0             TX-total: 0
  ----------------------------------------------------------------------------

  +++++++++++++++ Accumulated forward statistics for all ports+++++++++++++++
  RX-packets: 1              RX-dropped: 0             RX-total: 1
  TX-packets: 0              TX-dropped: 1             TX-total: 1
  ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

Done.
testpmd> show  port stats all

  ######################## NIC statistics for port 0  ########################
  RX-packets: 1          RX-missed: 0          RX-bytes:  8996
  RX-errors: 0
  RX-nombuf:  0         
  TX-packets: 0          TX-errors: 0          TX-bytes:  0

  Throughput (since last show)
  Rx-pps:            0          Rx-bps:            0
  Tx-pps:            0          Tx-bps:            0
  ############################################################################

  ######################## NIC statistics for port 1  ########################
  RX-packets: 0          RX-missed: 0          RX-bytes:  0
  RX-errors: 0
  RX-nombuf:  0         
  TX-packets: 0          TX-errors: 1          TX-bytes:  0

  Throughput (since last show)
  Rx-pps:            0          Rx-bps:            0
  Tx-pps:            0          Tx-bps:            0
  ############################################################################

> > +				rte_pktmbuf_free(mbuf);
> > +				continue;
> > +			} else {
> > +				break;
> > +			}
> else is not needed here.

[idog] ok
 
> > +		}
> >  		num_tx++;
> >  		tx_bytes += len;
> >  		rte_pktmbuf_free(mbuf);