Help stabilising mini-gmp

Marco Bodrato bodrato at mail.dm.unipi.it
Mon Nov 21 20:30:58 UTC 2016


Ciao,

Il Lun, 21 Novembre 2016 6:47 pm, Niels Möller ha scritto:
> tg at gmplib.org (Torbjörn Granlund) writes:
>
>> Of the remaining https://gmplib.org/devel/mini-gmp-status.html issues I
>> worry most about #2.  Marco adjusted the parameters to make it faster,
>> but I remain unconvinced that g5.gmplib.org-dyn:32 really needed 400
>> seconds for the test with old parameters.  I suspect the code can hang
>> for certain seeds.  (We cannot tell the seed because of #1.)
>
> If it happens again, the seed should be printed out.
> https://gmplib.org/repo/gmp/rev/5abbd164e2a3

I tried the test on a 18-years old 32-bits CPU I'm currently using. A
single 8000-bit Miller-Rabin round took 20 seconds with mini-gmp.
That's why I reduced the size. With 2000-bit operands I assume the worst
execution time will be reduced by a factor 18.

The hypothesis "its time varies hugely" is surely true. Before the
changeset 17099, on my machine, fluctuations between 2 and 60 seconds
where the norm. Of course a seed that require many MR rounds on big
operands is unlikely...

Best regards,
mb

-- 
http://bodrato.it/toom/



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