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Old 2010-07-25, 06:36   #4
S485122's Avatar
Sep 2006
Brussels, Belgium

68A16 Posts

Originally Posted by Rhyled View Post
If you do allocate a worker to P-1, make sure you assign it a reasonable amount of memory. I think the default is 8 MB, but 1000+MB significantly boosts the chance of finding a factor. Most Core i7 systems have a decent amount of memory to match their processor.
The minimum amount of memory to allocate to Prime95 to receive P-1 assignments is 300 MiB, see the assignment rules on the GIMPS site. (8 MiB is the default memory allocation, if you do not change anything after installing. With that memory allocation the program cannot execute the second stage of the P-1 factorisation.)

Indeed 1000 Mib or more gives better chances of finding a factor, because the program will use higher bounds in its search. A thing to keep in mind : the core that will do P-1 work will use that memory two thirds of the time since stage 2 takes about twice the time of stage 1.

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