Discussion related to cado-nfs

[paul zimmermann <Paul.Zimmermann@inria.fr>]

       Hi Valentin,

> From: Valentin Janser <valentin@wans-janser.de>
> Date: Wed, 15 Apr 2020 02:12:29 +0200
> 
> Hello there,
> 
> 
> in the last time I get more and more interested in your project.
> 
> That's why I upgraded one of my servers from a single E5-2680 to two
> E5-2680s.
> 
> For testing purposes I used the RSA-100-number from the wikipedia page
> "rsa numbers"
> (1522605027922533360535618378132637429718068114961380688657908494580122963258952897654000350692006139).
> 
> With one single CPU I get: CPU time: 10574s    WCT: 911s
> 
> With both CPUs I get:         CPU time: 24070s    WCT: 987s.
> 
> I use the following command: ./cado-nfs.py <number> server.ssl=no
> --server-threads <16/32> --slaves <8/16> --client-threads 2
> 
> The CPU usage is nearly 100 % in both cases.
> 
> 
> Why does the second CPU not achieve any speedup whatsoever?
> 
> Do you need futher debug information?
> 
> 
> Thanks in advance!
> 
> 
> Valentin Janser

this probably means that "With both CPUs" you have more threads that cores,
thus you cannot get more efficiency. What do you get without any argument
like --server-threads, --slaves or --client-threads? The default setting
should be close to optimal. More information could be the first lines of
the cado-nfs.py console log.

Best regards,
Paul