[Cado-nfs-discuss] A question on CADO-NFS 2.1

paul zimmermann Paul.Zimmermann at inria.fr
Mon Jun 15 10:27:03 CEST 2015


       Dear Narges,

> Date: Mon, 15 Jun 2015 12:43:32 +0430
> From: narges mousavi <mousavi.nrgs at gmail.com>
> 
> To whom it may concern,
> 
> According to the results mentioned in the main page of CADO-NFS
> <http://cado-nfs.gforge.inria.fr/> (Features subsection), can we say
> CADO-NFS 2.1 is two times faster than CADO-NFS 1.1? If so, can we refer to
> this result for larger numbers or not?

as you can see in the table, the speedup of 2.1 wrt 1.1 is not monotonous:
2.3 for RSA-120, 1.3 for RSA-130, 1.4 for RSA-140 and 2.2 for RSA-155. Note
also that for another (say) 155-digit number you might get a different ratio.
Thus we cannot say that CADO-NFS 2.1 is two times faster than CADO-NFS 1.1.
However it shows that CADO-NFS 2.1 is globally much faster than 1.1. For
larger numbers we don't have real figures but I'm confident it is similar.

> As the second question, we had set of factorizations on large numbers with
> CADO-NFS 1.1 and overally got more better results than the reported results
> that are shown in the CADO-NFS's site (more than 6 times faster). We can
> not find out what's the main reason of this different performances. Our
> test bed features are as the following:
> 
> - Intel  Xeon  X7560  2.27GHz  ,   4cpu*8*2 thr = 64 core (we used 60
> threads)
> - 25MB cache, 64GB RAM
> 
> Best Regards,
> Narges

our table displays the total cpu time, i.e., with 16 threads we sum up the
time spend for all threads. It would be very surprising that you get a 6-times
speedup. Can you reproduce on the RSA-xxx numbers?

Best regards,
Paul Zimmermann


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