Re: octave memory

[Rob Mahurin]

On Feb 11, 2009, at 11:45 AM, John W. Eaton wrote:
> On 11-Feb-2009, Søren Hauberg wrote:
>
> | ons, 11 02 2009 kl. 17:31 +0100, skrev jean francois sauvage:
> | > 2) Actually, the "who" command gives information about the size of
> | > variables. This is not exactly what I need. I need to know how  
> much
> | > memory has been allocated while the execution of a program.
> | >
> | > the function memory() of IDL returns 4 arguments :
> | >  - the actual amount of dynamic memory used by IDL
> | >  - the number of memory allocation since last call to memory()
> | >  - the number of memory unallocation since last call to memory()
> | >  - the maximum amount of dynamic memory readched since last  
> call to memory()
> | >
> | > I am looking for something similar (particularly for the first and
> | > fourth arguments) in octave.
>
> Octave doesn't keep track of these statistics.
>
> Why do you think you need this information?


I had a problem where this information would have been useful, and I  
wound up sort-of getting it from the operating system.

I had several thousand data files, each containing a 48x100x10,000 =  
200MB array of four-bit integers from a set of analog-to-digital  
converters (and about 100MB of other stuff).  For some parts of my  
analysis I needed only to do arithmetic with these integers, and an  
ugly set of loops in Some Other Language was much harder to tweak  
than a few lines of reshape(), sum(), diff().  For other parts I  
needed to convert to floating-point, or a conversion to floating- 
point would happen implicitly somewhere.  I spent a bunch of  
debugging time looking for those 400MB temporaries.

I wound up keeping a running tally of the memory used with a shell  
script that called "free" and wrote to a file.  An octave function  
where I could have written
> memory; my_function(data); memory
> ## maximum memory usage between calls: 1.5 GB
would have sped this debugging along quite a bit.

Cheers,
Rob

--
Rob Mahurin
Department of Physics and Astronomy
University of Tennessee                 865 207 2594
Knoxville, TN 37996                     address@hidden