Re: tbench regression on each kernel release from 2.6.22 -> 2.6.28

[Ilpo Järvinen]

On Mon, 11 Aug 2008, David Miller wrote:

> From: Christoph Lameter <cl@xxxxxxxxxxxxxxxxxxxx>
> Date: Mon, 11 Aug 2008 13:36:38 -0500
> 
> > It seems that the network stack becomes slower over time? Here is a list of
> > tbench results with various kernel versions:
> > 
> > 2.6.22		3207.77 mb/sec
> > 2.6.24		3185.66
> > 2.6.25		2848.83
> > 2.6.26		2706.09
> > 2.6.27(rc2)	2571.03
> > 
> > And linux-next is:
> > 
> > 2.6.28(l-next)	2568.74
> > 
> > It shows that there is still have work to be done on linux-next. Too close to
> > upstream in performance.
> > 
> > Note the KT event between 2.6.24 and 2.6.25. Why is that?
> 
> Isn't that when some major scheduler changes went in?  I'm not blaming
> the scheduler, but rather I'm making the point that there are other
> subsystems in the kernel that the networking interacts with that
> influences performance at such a low level.

...IIRC, somebody in the past did even bisect his (probably netperf) 
2.6.24-25 regression to some scheduler change (obviously it might or might 
not be related to this case of yours)...


-- 
 i.
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