repeatable crash on RELENG7

[Kevin Oberman]

> Date: Tue, 2 Dec 2008 19:33:00 +0300
> From: "Alexandr Pakhomov" <pahom.rt at gmail.com>
> Sender: owner-freebsd-stable at freebsd.org
> 
> On Tue, Dec 2, 2008 at 5:12 PM, Mike Tancsa <mike at sentex.net> wrote:
> 
> > At 08:38 AM 12/2/2008, Kostik Belousov wrote:
> >
> >> >
> >> > mdconfig -a -t malloc -s 1800M
> >> You cannot have ~ 2Gb of kernel memory allocated for md, at least not on
> >> i386.
> >>
> >
> > Thanks,  how do I find out what the limit is on a machine ? Is it
> > vm.kvm_size ?
> >
> >
> >        ---Mike
> > _______________________________________________
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> >
> 
> Try tune both vm.kmem_size and vm.kmem_size_max via /boot/loader.conf. They
> are equal to 330M by default.

Mike,

Let me second Kris's suggestion. I can think of very few cases where
malloc backed is in any way better than swap backed. Many people assume
that swap-backed performance is better, but this is only the case if you
run out of memory (and that is full memory, not kvm).

md is still RAM based and very fast. The current mdconfig should be
defaulting to swap-backed devices, but I don't see any indication of
that in the man page, so I may be wrong.
-- 
R. Kevin Oberman, Network Engineer
Energy Sciences Network (ESnet)
Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab)
E-mail: oberman at es.net			Phone: +1 510 486-8634
Key fingerprint:059B 2DDF 031C 9BA3 14A4  EADA 927D EBB3 987B 3751
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