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Re: IDL Memory Management [message #18460 is a reply to message #18458]

Fri, 07 January 2000 00:00

Craig Markwardt
Messages: 1869
Registered: November 1996

Senior Member

davidf@dfanning.com (David Fanning) writes:

> Craig Markwardt (craigmnet@cow.physics.wisc.edu) writes:
>
>> Windows used to have a non-linear addressing model when physical
>> system memory was scarce. Memory was allocated in chunks which could
>> be moved around by the Windows as needed, thus alleviating the above
>> fragmentation problem. I think however that more recent versions of
>> Windows have accepted the linear "Unix" model of memory architecture
>> that I have described.
>
> As I understand it, the compiler used for the Windows versions
> of IDL *can* return process memory back to the OS. But it is
> the only one to do so. It is not a feature, apparently, of
> UNIX, Mac, and VMS compilers, which rely on Malloc and Free
> for dynamic memory allocation.

I suppose I am picking nits now. The fragmentation problem actually
has nothing to do with the Unix compilers, malloc or free. The
problem is that Unix-style processes have memory that is one
dimensional without holes. [ To get technical, blame it on the
internal brk() function. ]

Windows NT also has a single linear memory space for processes, but it
may possibly have more features to deal with fragmentation
efficiently.

Nit-ingly yours,
Craig

--
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Craig B. Markwardt, Ph.D. EMAIL: craigmnet@cow.physics.wisc.edu
Astrophysics, IDL, Finance, Derivatives | Remove "net" for better response
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[Message index]

		Re: IDL Memory Management By: davidf on Fri, 07 January 2000 00:00
		Re: IDL Memory Management By: Craig Markwardt on Fri, 07 January 2000 00:00
		Re: IDL Memory Management By: davidf on Fri, 07 January 2000 00:00
		Re: IDL Memory Management By: Craig Markwardt on Fri, 07 January 2000 00:00
		Re: IDL Memory Management By: wbiagiot on Fri, 07 January 2000 00:00
		Re: IDL Memory Management By: Craig Markwardt on Thu, 06 January 2000 00:00

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