Subject: Re: Netperf TCP_RR(loopback) 10% regression in 2.6.24-rc6, comparing with 2.6.22

From: "Zhang, Yanmin" <[email-masked]>
Date: Tue, 22 Jan 2008 14:51:04 +0800

On Mon, 2008-01-21 at 22:22 -0800, David Miller wrote:
> From: "Zhang, Yanmin" <[email-masked]>
> Date: Tue, 22 Jan 2008 14:07:19 +0800
> 
> > I am wondering if UDP stack in kernel has a bug.
> 
> If one server binds to INADDR_ANY with port N, then any other socket
> can be bound to a specific IP address with port N.  When packets
> come in destined for port N, the delivery will be prioritized
> to whichever socket has the more specific and matching binding.
What does 'more specific' mean here? I assume 127.0.0.1 should be
prioritized before 0.0.0.0 which means packets should be queued to
127.0.0.1 firstly.

> So the kernel is fine.
But kernel now queues packets to 0.0.0.0.

> 
> Netperf just needs to be more careful in order to handle this kind of
> case more cleanly.
It's better if kernel works more reasonable.

-yanmin