it's the output, not ack coalescing (Re: TSO and FreeBSD vs Linux)

[Barney Cordoba]

________________________________
 From: Luigi Rizzo <rizzo at iet.unipi.it>
To: Barney Cordoba <barney_cordoba at yahoo.com> 
Cc: "freebsd-net at freebsd.org" <freebsd-net at freebsd.org>; Adrian Chadd <adrian at freebsd.org> 
Sent: Sunday, August 18, 2013 5:16 PM
Subject: Re: it's the output, not ack coalescing (Re: TSO and FreeBSD vs Linux)
 

On Sun, Aug 18, 2013 at 11:01 PM, Barney Cordoba
<barney_cordoba at yahoo.com>wrote:

> That's fine, it's a test tool, not a solution. It just seems that it gets
> pushed as if it's some sort of real
> world solution, which it's not. The idea that bringing packets into user
> space to forward them rather
> than just replacing the bridge module with something more efficient is
> just silliness.
>

you might want to have a look at the VALE switch

http://info.iet.unipi.it/~luigi/vale/

the upcoming version can attach physical interfaces to the switch and keep
all the processing within the kernel.


> If "pushing packets" was a useful task, the solution would be easy.
> Unfortunately you need to do
> something useful with the packets in between.
>
>
there are different definitions of what is "useful":
sources, sinks, forwarding, dropping (anti DoS), logging, ids,
are all useful for different people. The mistake, i think,
is to expect that there is one magic solution to handle all the useful
cases.

cheers
luigi
_______________________________________________



Nobody claimed that there was a magic solution. But when so much time and brainpower
is spent working on kludges (instead of doing things that have mainstream usefulness), it
results in either 1) fewer people using it or 2) the kludges become accepted solutions, simply
because someone did it. Polling, dummynet, netgraph, flowtable and buf_ring
are all good examples. 

It's the big negative of open source, particularly for the bigger projects. Once someone has
done "something", it not worth the effort in most cases to do it in a more correct way; and 
the something becomes all that's available.

BC