Arithmetic without limitations?

Joerg Arndt arndt at
Thu Feb 11 15:14:04 CET 2010

* Torbjorn Granlund <tg at> [Feb 11. 2010 14:57]:

> Special explicit swap files in a general purpose library is not imho a
> good design.  In a special purpose program, perfectly fine.  (Perhaps
> one could consider an optional interface in GMP where one makes
> available explicit swap files, I haven't thought about that.)

For performance reasons explicit files (better: partitions)
are almost a must.  Using swap space you rely on several
assumptions, e.g. that the reads and writes are from and to
big linear pieces of the disk.  Even if this is 'typically'
true very bad behaviour may occur in some cases.

Note you have _no_ control about how the kernel really maps
stuff (mem pages <--> disk blocks).

Allowing an FFT that is not organized as mass storage
transform to cause swapping is asking for total disaster
(performance wise).

> -- 
> Torbjörn
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