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SubjectRe: tbench regression on each kernel release from 2.6.22 -> 2.6.28
On Mon, 11 Aug 2008, David Miller wrote:

> From: Christoph Lameter <cl@linux-foundation.org>
> 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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