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Date: Fri, 4 Mar 2005 18:47:04 -0500
From: David Schultz <das@FreeBSD.ORG>
To: Peter Jeremy <PeterJeremy@optushome.com.au>
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cc: cvs-src@FreeBSD.ORG
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cc: Julian Elischer <julian@elischer.org>
cc: cvs-all@FreeBSD.ORG
Subject: Re: cvs commit: src/sys/kern kern_sig.c
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On Sat, Mar 05, 2005, Peter Jeremy wrote:
> On Fri, 2005-Mar-04 16:23:29 -0500, David Schultz wrote:
> >On Fri, Mar 04, 2005, Julian Elischer wrote:
> >> for a start I'd like to add a sysctl to turn off swapping out kernel 
> >> stacks..
> >> then if someone had a reproducible or atleast 'common" problem,
> >> we could suggest turning it off to see
> >> if it fixes the problem.. that would be a big smoking gun..
> >
> >You mean like vm.swap_enabled?  ;-)
> 
> That turns off all swapping and isn't going to answer the question.
> Julian's point does seem reasonable - there is a potential problem
> relating to swapping kernel threads but there's no clear evidence
> that it is or isn't a real problem.  Adding a knob to easily control
> the behaviour would be useful - we stand to get some real data and
> can then better make a decision as to how to proceed.

vm.swap_enabled *does* control kstack swapping only.  What you're
thinking of, namely, paging in general, is controlled by whether
or not you have any swap devices configured.