memory problem with GMP 5
Torbjorn Granlund
tg at gmplib.org
Fri Jan 15 17:11:15 CET 2010
Paul Zimmermann <Paul.Zimmermann at loria.fr> writes:
I've noticed that GMP 5 uses much more internal memory for big multiplications
than previous versions. For example with the following program on a 64-bit
Core 2, top gives a maximal "RES" memory of 1.6g for GMP 4.3.2, and 2.4g for
GMP 5, i.e., 50% more!
Ouch!
have you checked balanced multiplies too? Do they, too, require much
more memory than 4.3?
Note that the inputs a and b use about 0.5g, as does the result a*b. Thus
GMP 4.3.2 uses extra memory of 0.6g to perform the product, whereas GMP 5
uses 1.4g.
With a given memory limit, this means that GMP 4.3.2 is able to perform larger
computations than GMP 5.
This ought to be fixed. My goal is actually to gradually *lower* GMP's
memory thirst!
--
Torbjörn
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