Re: Unix sockets via TCP on localhost: is TCP slower?

From: Olaf van der Spek
Date: Fri Nov 14 2008 - 04:09:46 EST


On Fri, Nov 14, 2008 at 9:56 AM, David Miller <davem@xxxxxxxxxxxxx> wrote:
>> Why would you use windowing, ACKs, flow control and encapsulation on localhost?
>
> So that you could firewall, shape, redirect, and make other
> modifications to the traffic, as well as see it in tcpdumps. That's
> the power of Linux, and yes people do this stuff and yes people do
> want these features to work over loopback.
>
>> I expected the kernel to copy data directly from user-space of the
>> sending process to a kernel buffer of the receiving process, much like
>> UNIX sockets.
>
> Then all of the above features and debugging facilities go away.

So instead the recommendation is for all apps to support both TCP and
Unix sockets?
If you then use Unix sockets, you still lose all of those facilities
and as a bonus, your apps are more complex.

I'd prefer a switch that could be enabled to use such a shortcut for TCP.
Firewalls should still work mostly (on connect), redirect would still work.
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