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Message-ID: <03c201c17dcc$4e14c930$1a01a8c0@allyourbase>
From: "Dan Maas" <dmaas@dcine.com>
To: <adam-dated-1007982419.3acea7@flounder.net>
Cc: <linux-kernel@vger.kernel.org>
In-Reply-To: <fa.g60uruv.1n5cija@ifi.uio.no> <fa.h8gf0vv.18kimh8@ifi.uio.no>
Subject: Re: Maximum heap size?
Date: Wed, 5 Dec 2001 15:34:54 -0500
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> If you are hitting a 1GB limit I would assume the jvm isn't very bright
> about its allocation of resources. You should run out at something like
> 2.5Gb of allocations. (you lose some to app and library maps)

Specifically, the jvm is probably getting memory from brk(), because brk()
only operates in the ~1GB region between 0x08000000 + epsilon (where the
executable ends) and 0x40000000 (where shared libs begin). The easiest way
to get more than 1GB is to mmap() anonymous pages (which will come from the
remaining ~2GB region between 0x40000000 and 0xBFFFFFFF). e.g. glibc will
use anonymous mmap() to fulfill large malloc() requests.

Regards,
Dan

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