libpcap perf improvement? latest ideas?

[Robert Watson]

On Thu, 5 Oct 2006, Jochen Kaiser wrote:

> after reading a german master thesis [1] (dated 12/2004) about pcap 
> performance (with comparison of linux and freebsd) I searched freebsd 
> resources for pcap improvements. Unofortunately I did not find any 
> improvements like PF_RING and/or efforts for reducing the number of copy 
> operations from device to user space.
>
> Maybe I think too simple because I don't know how SMP fine locks are 
> influencing this (maybe it is very complex to improve that when you want to 
> avoid side effects.).
>
> Or maybe it is not important at all, because real applications use DAG 
> boards?
>
> I would appreciate any discussion here.
>
> greetings,
> Jochen
>
> [1] www.net.in.tum.de/teaching/projects/docs/schneider_SEP_slides2.ps
> [2] www.endace.com

Quite a bit of work has been done on zero-copy for BPF, but none of it really 
commitable.  Christian Peron (CC'd) and I have been talking about doing 
something that is commitable, but some of the details (such as memory 
ownership) are still very much up in the air.  PF_RING takes an interesting 
approach, and one we should look at, but we'd also like to keep all the 
benefits of BPF rather than discard them, so need to consider how best to 
apply elements of the approach in our context.  I'd like to see something like 
this happen for FreeBSD 7.0, with a possible backport if it goes really well. 
:-)

Robert N M Watson
Computer Laboratory
University of Cambridge