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Date:      Tue, 06 Jul 1999 17:20:53 +0000
From:      rob <rfleming@cc.weber.edu>
Cc:        freebsd-smp@FreeBSD.ORG
Subject:   Re: Intel SC450NX hangs under high disk/memory load (2)
Message-ID:  <37823AF4.7EA3BDA@cc.weber.edu>
References:  <Pine.OS2.3.95.990706085442.237A-100000@CENTRAL> <99070612032100.30449@par28.ma.ikos.com>

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Just a thought.

Richard Cownie wrote:

> On Mon, 05 Jul 1999, Andrew MacIntyre wrote:
> > On Mon, 5 Jul 1999, Dmitry Flitmann wrote:
> >
> > > Any ideas - are there any problems with memory over 512M -
> > > either kernel, or maybe some drivers/controllers?
> >
> > {...}
> >
> > > >MAXUSERS is 512 (or 256)

I was playing with the setting a while ago trying to get better performance on
a dual pII 400 with 512meg ram.  I had hang problems similar to this.  I read
some notes that stated that this has actually very little to do with the
number of users that can access a machine?
Anyway I would try pushing this number back down.  It uses a very large amount
of memory.




>
> >
> > I haven't seen any responses to your query via the list, so...
> >
> > Given that I remember your described usage patterns, I seem to recall
> > seeing recommendations to use a smaller MAXUSERS value (say 128) and
> > directly modify the specific values which may need to be increased, such
> > as NMBCLUSTERS (hope I got that right...).  I think it had to do with the
> > MAXUSERS calculation causing kernel memory usage to expand too much.
>
> I'm running 4.0-CURRENT from about 6 June on an SC450NX with
> 4 x Xeon-500 and 4GB DRAM.  The kernel is built with these sizing
> options:
>
>   maxusers  256
>   options VM_KMEM_SIZE_MAX=0x20000000UL
>   options NMBCLUSTERS=8192
>
> If you don't set VM_KMEM_SIZE_MAX, I believe the default is 80MB,
> which is not much for a machine with >1GB of DRAM.  However, this
> would probably cause a panic rather than the behaviour you're
> seeing.
>
> I believe Linux is good for approx 1GB of DRAM, and latest kernels
> can be tuned to support 2GB DRAM.  As far as I know FreeBSD 3.x
> supports 2GB DRAM (not sure about 3GB ?) - you need a recent 4.0-CURRENT
> to support the full 4GB.  It turns out to be 4GB - 97MB, because
> the SC450NX chipset/bios put some of the DRAM above the 4GB address
> boundary.
>
> Richard Cownie (tich@ma.ikos.com)
>
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Rob



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