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

narges mousavi mousavi.nrgs at gmail.com
Tue Jun 23 07:47:57 CEST 2015


Dear Prof. Zimmermann
Thank you for your fast reply.

It was assumed that the reported results are the total spending time with
16 threads, not the sum up of all thread’s time; So, we made a mistake in
comparison of our results with yours.

We plan to run the CADO-NFS 2.1 with 128 threads. It would be grateful if
you can help us by answering this question:
We know that the sieving step can be run using almost unlimited number of
threads, but we don’t have enough knowledge about the other steps. How many
threads can we use in Polynomial selection, Linear Algebra and Square
roots?  Is there any limitations? (Max or min…?)

Best Regards
Narges

On Mon, Jun 15, 2015 at 12:57 PM, paul zimmermann <Paul.Zimmermann at inria.fr>
wrote:

>        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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