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MemoryInUse[] reports wrong numbers?

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  • Subject: MemoryInUse[] reports wrong numbers?
  • From: David Harrison <harrison%faraday at>
  • Date: Thu, 22 Apr 1993 09:11:52 -0400

We are running MMA 2.1 on an HP9000/750 (HP-UX 8.07).  When a MMA session
gets fairly large ( >~ 8 Megabytes or so), MemoryInUse[] gives results
which are greatly different from those reported by either HP's Glance,
top, or vmstat(1), all three of which agree that MemoryInUse[] is returning
a number about a factor of 2 too small.   Note that I am comparing the
resident program size from Glance/top/vmstat to MemoryInUse[], not the
total program size.  Further, Glance/top/vmstat seem to be correct since
the UNIX kernel begins paging when MMA has eaten all the RAM.

As an undergraduate computing facility, we placed a governor on the size
of a MMA session based on David Withoff's <withoff at> posted
automatic invocation of Share for large kernels, supplemented by Todd
Gayley's <tgayley at> extension invoking ClearInOut and CleanSlate
if Share doesn't sufficiently reduce the size of the kernel, and further
extended by me to Exit[1] if those don't do the job.

We now limit to MemoryInUse[] of 8000000 (8 Megs) to get an effective
limit of 16 Megs.

Is this a generic bug or HP specific?  Am I misinterpreting something
and it isn't a bug at all? Finally, could it be related to Jesus Rivero's
recent post to this group of problems with big packages under Windows?
David Harrison                             | "We place no reliance on virgin
Dept. of Physics, Univ. of Toronto         |   or pigeon,
Inet: harrison at |  Our method is science, or aim
Tel: 416-978-2977  Fax: 416-978-5848       |   is religion."  Aleister Crowley

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