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Date: Thu, 7 Aug 2008 11:26:06 -0500 (CDT)
From: Mark Tinguely <tinguely@casselton.net>
Message-Id: <200808071626.m77GQ6vf033517@casselton.net>
To: mkhitrov@gmail.com
In-Reply-To: <489B1311.9020100@FreeBSD.org>
Cc: freebsd-questions@freebsd.org
Subject: Re: 64-bit Linux Binary Compatibility (for Matlab)
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> Date: Thu, 7 Aug 2008 09:47:45 -0400
> From: mkhitrov@gmail.com
> To: freebsd-questions@freebsd.org
> Apparently Matlab tries to allocate a continuous chunk of memory, and
> we needed to upgrade to 64-bit hardware to give it access to more than
> 1GB of memory, which is about the most that it was able to get before.
> It's a lousy explanation, but I wasn't employed at this place when
> this diagnosis was made.

Large contiguous allocations have to occur during or soon after booting because
of memory fragmentation. 

I can see that larger memory configurations on a 64 bit OS has a better
chance of allocating big chunks like this. Make sure you have much more
than 4G RAM since some hardware needs memory below 4GB, and the contiguous
allocation at boot favors memory towards the top of the 4GB range.

--Mark Tinguely.