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Date: Thu, 21 Nov 2002 12:55:15 -0800
From: David Schultz <dschultz@uclink.Berkeley.EDU>
To: Petri Helenius <pete@he.iki.fi>
Cc: freebsd-questions@FreeBSD.ORG, freebsd-net@FreeBSD.ORG
Subject: Re: panic: kmem_map too small
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	freebsd-questions@FreeBSD.ORG, freebsd-net@FreeBSD.ORG
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Thus spake Petri Helenius <pete@he.iki.fi>:
> > > With about 150M in use and KVA_PAGES undefined in config (default),
> > > both 4.7-STABLE and 5.0-CURRENT panic (1G installed memory).
> >
> > Yes, the default is 256, IIRC.  That corresponds to 1 GB of KVA,
> > and you have only 1 GB of physical memory to back it.  I take it
> > this is a very busy machine.  Short of getting more memory, you
> > can decrease memory utilization by the network, e.g. by decreasing
> > TCP window sizes, or you can limit memory usage by the network so
> > you don't get panics.  I forget the details here, so perhaps
> > someone else can fill them in.
> >
> The thing I´m concerned about that if with 150M kernel memory usage and
> >200M free and >300M inact memory the system panics, how much "extra"
> memory is needed to keep it running? And the swap is never touched.

Most kernel memory is not pageable, so swap probably won't help
you.  Your `kmem_map too small' error message should report to you
the size of the attempted allocation and the size of kmem_map.
If the map really isn't full, I'm not sure why you would get this
panic, unless you're somehow running into excessive fragmentation.

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