"Feature" request: Keep new B2 value when memory allotment increased

JuanTutors · 2006-12-17, 03:59

Here's the situation:

950MB: B1=400000, B2=103 00000
1000MB: B1=400000, B2=104 00000

However, when stage 2 has already been started, even though the B1 values stays the same, Prime95 still says "Ignoring suggested B2 value, using B2=10300000 from the save file".

S485122 · 2006-12-17, 08:02

The 50 MB increase in memory does not make it worth to redo all work already done. Next time the program will have to do stage 2 of P-1 factoring it will use the bigger value.

If you absolutely want Prime 95 to use 1000MB instead of 950 MB on the current exponent, stop the program and delete the intermediate result file, something like "m0C15621.000" for an exponent like 37 015 621. Restart Prime95 it will start the P-1 computations all over. You would lose all work already done on the exponent (stage 1 and stage 1 GCD and the start of stage 2.) I do not know by how much you would increase your chances of finding a factor with the new B2 value, it is probably marginal.

JuanTutors · 2006-12-18, 05:19

Quote:

Originally Posted by Jacob Visser

The 50 MB increase in memory does not make it worth to redo all work already done. Next time the program will have to do stage 2 of P-1 factoring it will use the bigger value.

Do you know enough about the code to be sure that it has to restart stage 2 because of the new B2 value?

S485122 · 2006-12-18, 06:31

My answer was based on my understanding of bits and pieces of this forum, the FAQ and the wiki.

If I understood well changing the B1 and B2 limits, means the tables used for the P-1 stage 2 have to be recomputed. With the table changed it is not possible to resume the work. But I may be corrected by more knowledgeable people.

2006-12-17, 03:59	#1
JuanTutors "Juan Tutors" Mar 2004 571 Posts	"Feature" request: Keep new B2 value when memory allotment increased Here's the situation: 950MB: B1=400000, B2=103 00000 1000MB: B1=400000, B2=104 00000 However, when stage 2 has already been started, even though the B1 values stays the same, Prime95 still says "Ignoring suggested B2 value, using B2=10300000 from the save file".

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2006-12-17, 08:02	#2
S485122 "Jacob" Sep 2006 Brussels, Belgium 3657₈ Posts	The 50 MB increase in memory does not make it worth to redo all work already done. Next time the program will have to do stage 2 of P-1 factoring it will use the bigger value. If you absolutely want Prime 95 to use 1000MB instead of 950 MB on the current exponent, stop the program and delete the intermediate result file, something like "m0C15621.000" for an exponent like 37 015 621. Restart Prime95 it will start the P-1 computations all over. You would lose all work already done on the exponent (stage 1 and stage 1 GCD and the start of stage 2.) I do not know by how much you would increase your chances of finding a factor with the new B2 value, it is probably marginal.

2006-12-18, 06:31	#4
S485122 "Jacob" Sep 2006 Brussels, Belgium 7·281 Posts	My answer was based on my understanding of bits and pieces of this forum, the FAQ and the wiki. If I understood well changing the B1 and B2 limits, means the tables used for the P-1 stage 2 have to be recomputed. With the table changed it is not possible to resume the work. But I may be corrected by more knowledgeable people.