Re: 2.6.12 Performance problems

From: Danial Thom
Date: Wed Aug 24 2005 - 11:33:38 EST




--- Sven-Thorsten Dietrich <sven@xxxxxxxxxx>
wrote:

> On Tue, 2005-08-23 at 13:10 -0700, Danial Thom
> wrote:
> >
> > None of this is helpful, but since no one has
> > been able to tell me how to tune it to
> provide
> > absolute priority to the network stack I'll
> > assume it can't be done.
>
> History has proven that camp wrong almost 100%
> of the time.
>
> You were told to turn off kernel preemption.
>
> A diligent comparison requires that, since 2.4
> does not support kernel
> preemption, and a fair comparison requires
> holding all other things
> constant.
>
> In addition, there were several IP-level
> features mentioned in emails,
> that have been added to 2.6.
>
> You need to make sure those are all off by
> default, to keep your
> comparison relevant.
>
> All the answers are before you, review those
> emails, turn all that stuff
> off and retest.

I had tried turning off pre-emption, with little
difference. However linux had the same properties
before there was such a setting (of liking to
drop packets here and there for no apparent
reason under heavy load), so I didn't expect it
to make a huge difference. It seems typing on the
keyboard has the same effect with or without
pre-emption enabled.

IP is not involved in this test, so no IP stack
issues should be relevent.

Danial




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