[dpdk-dev] [PATCH v3 0/5] add dpdk packet capture support for tcpdump

[Thomas Monjalon]

Hi,

This series has not been reviewed enough to be ready for 16.04.
So it would be good to restart the discussion about the tcpdump requirements.

> packet capture flow for tcpdump:
> ================================
> Part of the design is implemented in secondary process (proc_info.c) and other part
> in primary process (eal_interrupt.c).

Why proc_info is used? Why not a dedicated tool?

> *User should request packet capture via proc_info application command line by passing newly
> added tcpdump command line options i.e. [--tcpdump (port,queue)] [ --src-ip-filter \"A.B.C.D\"]
> [--single-tcpdump-file].
> 
> Note: As basic support, a src ip filter option is provided for filtering the packets.
> This is optional. If user dont provide any src ip filter option all packets will be captured
> for tcpdump.

Why filtering? Why only on IP address? Why not BPF?

> 2: Because of the underlying pcap writing overhead packets can only be captured at slow rates.

What is the benefit of slow rate capture in DPDK?
Shouldn't we target a high rate mechanism?