AW: Serious TCP performance regression in 4.0?

["Karpinski, Jens (A.P.E. GmbH - IT-Security Engineer)" <J.Karpinski%ape-net.com@localhost>]

I got the same issue with iperf last week.
After a couple of tests with a new firewall-setup the throughput (measured by 
two NetBSD-Clients) was around 2.8 MBit/s (at least 80 MBit/s were expected).
After a lot of meaningless testing I repeated the measurement with two 
Windows-PCs running the same Version of iperf and got the expected result of 
~94 MBit/s. It looks like every time a NetBSD-Version of iperf is involved in 
the test the result is way to small.

I would like to know the reason for this behavior too, but according to your 
tests the problem will solve itself when I switch to NetBSD 5 this week.

Regards,

Jens

-----Ursprüngliche Nachricht-----
Von: tech-net-owner%NetBSD.org@localhost 
[mailto:tech-net-owner%NetBSD.org@localhost] Im Auftrag von Havard Eidnes
Gesendet: Sonntag, 30. November 2008 21:30
An: seanb%qnx.com@localhost
Cc: tech-net%NetBSD.org@localhost
Betreff: Re: Serious TCP performance regression in 4.0?

> > I have recently been made aware of what appears to be a serious
> > TCP bulk data transfer performance regression experienced by
> > NetBSD 4.0.
>
> Does setting net.inet.tcp.congctl.selected=reno (default is newreno)
> make a difference?

Nope, it didn't.

However, I may have to retract my claim, the problem appears to
be specific to the "iperf" program.  Re-doing some of the tests
with good old ttcp does not show the same behaviour.

It would still be interesting to know what "iperf" does to
trigger the problem in 4.0, but the solution to that is now not
urgent.

Regards,

- Håvard