Subject: Re: AIM9 regression

From: Stephen Hemminger <[email-masked]>
Date: Wed, 24 Sep 2008 08:16:03 -0700

On Tue, 23 Sep 2008 22:18:31 -0700 (PDT)
David Miller <[email-masked]> wrote:

> From: Herbert Xu <[email-masked]>
> Date: Wed, 24 Sep 2008 13:12:37 +0800
> 
> > On Tue, Sep 23, 2008 at 01:14:27PM -0500, Christoph Lameter wrote:
> > > I just dont seem to be able to get 2.6.27 to behave in a speedy way network
> > > wise. Configured out various components (netfilter, etc etc) but I still keep
> > > getting these aim9 result against 2.6.22:
> > 
> > Could you please compare this against something less ancient,
> > like 2.6.26 perhaps?
> 
> Herbert, this is part of the tbench regression issues.  Christoph
> took tbench from 2.6.22 until 2.6.27 and at basically every release
> tbench performance suffered noticably.
> 
> Now, he's taking the AIM9 benchmark networking numbers and showing
> that the same exact effect is seen there too.
> 
> It really behooves us to start doing something proactive about this
> blindingly obvious set of networking performance regressions through
> the past 6 or so releases instead of barking at the reporters saying
> things like "try this, try that, what's your config" etc.
> 
> :-)

These loopback benchmarks are often more sensitive to scheduler than networking
changes.