Thread: YAFU 2.0
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Old 2021-06-16, 15:17   #139
bsquared's Avatar
Feb 2007

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A couple updates, one related to a msieve change that I've just noticed.

As of msieve 1023, gnfs cpu (and maybe gpu?) poly selection now defaults to a massive 8640000 seconds deadline per coefficient searched. That can be changed with a "poly_deadline" parameter, which I didn't know about before. Noticed it recently when trying to gnfs a c120 or so, and having it spend hours in multi-threaded poly select for a 30 minute job. The update now uses the poly_deadline parameter and it seems to work better.

Although, it finds way fewer polys than before. The parameter tables changed in msieve 1023 as well, and some seem to have pretty strict minimum E-score requirements.

When running snfs with an input poly file, yafu will do a quick search for a better skew value. So far it doesn't do anything with this info other than print it to the screen, but after some more testing I might automatically update the input poly with the improved skew, if one is found.

I'm no longer supporting -psearch deep or -psearch wide for multi-threaded gnfs poly selection. Not sure if these were even used by anyone... I know I didn't use them. Now all searches are "fast", which was the default, and which divides the search time by the number of threads. -psearch {min | avg | good} can still be used to modify acceptable E-scores.* For small jobs I've found -psearch avg or even -psearch min to be faster, as any old poly will sieve almost as fast as another and you would like to get on with the sieving asap.

* the -psearch min | avg capability is where conflicts might occur with the new msieve poly parameter tables. I need to do more testing to know for sure. But for that c120 job I did recently, it found exactly one poly after 10 minutes of searching on 40 threads (over 6 thread-hours of searching). Specifying -psearch min won't do any good if msieve won't even return polys found near that score.

Last fiddled with by bsquared on 2021-06-16 at 15:22 Reason: potential conflict
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