[dpdk-users] mlx5 / tcpdump: packet drop

[Stephen Hemminger]

On Thu, 23 Jul 2020 17:10:31 -0400
PATRICK KEROULAS <patrick.keroulas at radio-canada.ca> wrote:

> Hello,
> 
> I'm trying to use tcpdump with dpdk support in order to benefit from
> dpdk performance and nice features from tcpdump, like filters etc.
> Traffic is constant but quite significant, 6 Gbps, captured by Mellanox
> ConnectX-5.
> 
> DPDK standalone works like a charm, no packet drop.
> $ testpmd -w 0000:01:00.0 -w 0000:01:00.1 -- --enable-rx-timestamp
> $ dpdk-pdump -- --pdump 'port=0,queue=*,rx-dev=/tmp/test.pcap'
> 
> However,when using libpcap/tcpdump on exact same hardware and
> dpdk version, 15% of the pkts are dropped by interface:

The libpcap version of packet capture has many copies, and lots
of extra system calls. The performance is likely to be less than doing
a native solution with the kernel.

It may get better in the future.