On 2/3/11 4:25 PM, Ryan Stone wrote:
On Thu, Feb 3, 2011 at 2:48 PM, Julian Elischer<jul...@freebsd.org> wrote:
I had never considered passing a set of packets, but after my initial
scoffing thoughts I realized that it would actually be a very interesting
thought experiment to see if the ability to do that would be advantageous in
any way. I tmay be a way to reduce some sorts of
overhead if using interrupt mitigation.
At $WORK we've put a rather considerable amount of effort into writing
what I'd call a poor-man's version of netgraph. Originally, in fact,
our application was entirely netgraph-based back when we were running
on FreeBSD 4. What we ended up implementing was the minimal set of
netgraph features our application needed, optimized for performance.
Passing packets around in batches was one of the performance
optimizations. There are some pretty big wins with that approach:
amortization of locking costs and other overhead, better cache
locality and it's easier to prefetch the data from packet n while
processing packet n-1.
That's actually one of the ways that we envisioned netgraph being used..
As a prototyping tool that would eventually be replaced by the same
node code hooked together
be a purpose-designed application. However we did too good a job in
implementing it so that
for a large percentage of the tasks the prototyping framework actually
does well enough.
The other use was for low speed L2 plumbing for WAN networking.
If I get some time I'll see if I can get something by the way of hard
numbers as to the advantages on our application.
_______________________________________________
freebsd-current@freebsd.org mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-current
To unsubscribe, send any mail to "freebsd-current-unsubscr...@freebsd.org"
