Subject: Re: Skipping TCP / UDP / IP checksums on loopback traffic
To: Nathan J. Williams <>
From: mouss <>
List: tech-net
Date: 10/27/2004 10:38:56
Nathan J. Williams wrote:
 > Right, I had veered from the original stated purpose and into the
 > abstract mental territory of "starting from scratch, if I want to make
 > a connection to myself, what do I do?" Of course, we're not starting
 > from scratch, so we've got PF_LOCAL. I think the argument I
 > hypothesized would have more appeal with those people ("young kids" or
 > something) who have only ever known IP networking, and whose answer to
 > "How do I make a local connection?" would be IP-centric rather than
 > popping up a layer.

well, people are "ip-centric" for valid reasons:

- there is no point in adding pf_local support in a networked 
application. One rarely needs more performances than what tcp offers.

- pf_local has its own problems. some platforms have it wrong and others 
don't even support it.

of course, if perf and/or security are a real concern, then pf_local may 
be the way to go.

 >>I'm still not aware of any real-world case where lo0 throughput is a
 >>significant bottleneck?  Speed up something that's well under 10% of
 >>your application, by some 10%[*]? Not a big win.
 > I'm not either, so I agree here.

I agree that we should avoid the benchmarketing race.