network performance problem

[Robert Watson]

On Wed, 13 Sep 2006, Ingo wrote:

> I`ve some problems with the network performance on my Soekris NET 4801. 
> (Freebsd 6.1 release-p3)
>
> When I start "netio" on the soekris and do a "netio localhost", I get about 
> 8.4 MB/sec, and when I start with "netio 192.168.0.11"(it´s localhost 
> address) I get only ~2.3 MB/sec. That´s what top says when I do:

What does "route get 192.168.0.11" return?

What happens if you force the localhost MTU from whatever the default is (most 
likely 16k) to the same as the ethernet interface?

Robert N M Watson
Computer Laboratory
University of Cambridge

>
> localhost
> CPU states:  2.3% user,  0.0% nice, 72.5% system, 25.2% interrupt,  0.0% idle
>
> 192.168.0.11
> CPU states:  1.2% user,  0.0% nice, 46.3% system, 52.5% interrupt,  0.0% idle
>
> As you can see, the interrupt load is more than doubled when I use the Ip 
> address, and
> I´ve no idea why.
>
>
> Here are some other throughput results of the soekris:
>
> openbsd# ftp 192.16.8.0.20	2.0 MB/sec
> openbsd# iperf localhost 1.4 Mbit/sec
> openbsd# iperf 192.168.0.11(it´s localhost address) 1.4 Mbit/sec
> openbsd# netperf localhost 70MB/sec
> openbsd# netperf 192.168.0.11(it´s localhost address) 70MB/sec
>
> freebsd# ftp 192.168.0.20  2.3 MB/sec
> Freebsd# iperf localhost 45 Mbit/sec
> Freebsd# iperf 192.168.0.11 (it´s localhost address) 19 Mbit/sec
> Freebsd# netperf localhost 67 Mbit/sec
> Freebsd# netperf 192.168.0.11 (it´s localhost address) 19 Mbit/sec
>
>
> What causes the difference between localhost and the ip address on Freebsd?
> On Openbsd there is no diffenerce at all.
>
>
> Greetings
> -- 
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