Currently I can do tcpdump -i eth1 -s 200 -w /some/usb/stick.cap at about 1.2 - 2MB/sec before saturating cpu on the wndr3700v2. (MB =megabyte)

I can r/w a usb stick at about 8/7 MB/sec. I haven' tried a 'real' hard disk.

About 50Mbit/sec I figure covers the 95 percentile of most home users to their ISP. 100Mbit would be better. Being drop-free would be really helpful on shorter tests....

I was also thinking about an in-kernel module that uses 'splice' to send the data to a file... as well as  the current jit work for bpf, using netfilter, and various other alternatives.

Or writing something in a iptables or tc filter to track things more sanely that web100 does....

Ideas?

---------- Forwarded message ----------
From: Fabian Schneider <fabian@ieee.org>
Date: Wed, Oct 19, 2011 at 6:03 PM
Subject: Options for making Linux suck less when capturing packets
To: Dave Täht <dave.taht@gmail.com>
Cc: Ahlem Reggani



Hi Dave,

as promised here are some pointers.

- http://www.ntop.org/products/pf_ring/

- And i think that libpcap since version 1.0 has builtin support for memory mapping, which was propose by Phil Woods [1].

- It might be worthwhile to check if the NIC supports any sort of interrupt coalescing or polling, instead of standard one interrupt per packet.

- I have to search a bit more for the code of my student (I changed employers twice since then).

best
Fabian

[1] http://public.lanl.gov/cpw/ramblings.html



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