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Date:      Wed, 14 Nov 2001 15:30:31 +0000
From:      David Malone <dwmalone@maths.tcd.ie>
To:        Eugene Grosbein <eugen@grosbein.pp.ru>
Cc:        stable@freebsd.org, hackers@freebsd.org
Subject:   Re: kern.vm.kmem.size
Message-ID:  <20011114153031.A16886@lanczos.maths.tcd.ie>
In-Reply-To: <20011113224730.A864@grosbein.pp.ru>; from eugen@grosbein.pp.ru on Tue, Nov 13, 2001 at 10:47:30PM %2B0700
References:  <20011111230817.A2325@grosbein.pp.ru> <20011113151329.A44837@walton.maths.tcd.ie> <20011113224730.A864@grosbein.pp.ru>

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On Tue, Nov 13, 2001 at 10:47:30PM +0700, Eugene Grosbein wrote:
> > you have enough physical memory. (By default there is about 1GB of
> > kernel address space, so you are unlikely to be running into this
> > limit - I don't think changing kern.vm.kmem.size will help you).
> 
> Are you shure? From LINT:

You're right - it is much smaller (I was thinking of something
else). However it is bigger than 12MB on most systems - I think it
will turn out to be 1/3 physical memory or 200MB, whichever is
less.

> It seems DIRHASH is limited with free space in the kernel malloc area.
> It even cannot utilize default 2M of vfs.ufs.dirhash_maxmem when I do not
> increase kern.vm.kmem.size.
> 
> So, how can I estimate needed value of kern.vm.kmem.size?

How much ram do you have in the machine? On a 4.4-RC1 machine
with 128MB of ram we don't have any problems getting dirhash
to use almost all of it's 2MB:

	vfs.ufs.dirhash_maxmem: 2097152
	vfs.ufs.dirhash_mem: 2085797

This is with the devault value for kern.vm.kmem.size. Maybe
you could print the value your system is getting with:

	echo print vm_kmem_size |  gdb -k /kernel /dev/mem

David.

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