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Re: [sage-devel] Re: Why does pari need 1Gig of memory allocated? William Stein Fri Nov 25 17:00:45 2011

On Tue, Nov 15, 2011 at 12:05 PM, Georg S. Weber
<[EMAIL PROTECTED]> wrote:
>
>
> On 15 Nov., 18:18, Jeroen Demeyer <[EMAIL PROTECTED]> wrote:
>> On 2011-11-15 18:09, Maarten Derickx wrote:> I think 1024000000 byte wich is 
>> about 1 gigabyte is a bit to much to
>> > allocate just at once. So the main question is where does this number
>> > come from and why is it so huge?
>>
>> The Heegner test simply needs that much memory...
>>
>> Normally you need between 2GB and 3GB of memory to run all doctests in
>> Sage successfully.
>
> Hmmm,
>
> I run regularly "make testlong" on my old G4 PowerPC Mac, and that
> system has only 768 MB RAM. Last time is just a couple of days ago

It's not the RAM that matters for "out of memory errors", but the
amount of "memory", as Jereon says.    You could probably build and
run the full test suite on a machine with 500MB RAM if you had
sufficiently fast swap.   That said, swap can be slow, so some tests
my time out even though they would eventually thrash through to
completion if you let them run long enough.

(I actually just built Sage-4.7.2. from scratch on a free Amazon EC2
instance with 600MB RAM.  It was crucial to create a swap file, since
otherwise linbox fails to build.)

I don't understand how swap space works on Macs.  It seems that the
operating system dynamically allocates it.  You probably have some on
your old 768MB RAM mac.

> with Sage-4.7.2, and e.g. heegner.py did pass OK. (There were only
> four failures in total, two w.r.t. intefacing: maxima.py and sage0.py,
> and two timeouts for elliptic curve computations:
> ell_rational_field.py and sha_tate.py).
> So there must be something different going on.
>
> @Maarten:
> Does the output you pasted mean that there is no swap space at all
> ("Swap:            0          0          0 "), i.e. neither an extra
> swap partition (fstab/mtab might show more info on this) nor some swap
> file? Even my old Mac swaps out memory pages to disk ...
>
> Cheers,
> Georg
>
> --
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-- 
William Stein
Professor of Mathematics
University of Washington
http://wstein.org

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