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Old 2011-12-12, 22:34   #1
EdH
 
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"Ed Hall"
Dec 2009
Adirondack Mtns

1101000100102 Posts
Default Using Several Instances of Aliqueit for a large gnfs job

For those who like the automation of Aliqueit and would like to work on larger numbers, but not wait quite so long for completion, I have been playing with a way to use several machines on the same gnfs job via Aliqueit. I'm not sure of the results, though and am asking for some comments on the following:

I recently ran a c135 on a 64-bit linux machine, with help from several 32-bit linux machines. What I did was to start the 64-bit machine and once the poly selection was done and relations were being added, I copied the ggnfs_###... directory and the ###.elf file to the other machines. I then got rid of the spairs files on those other machines. (I did some other things due to the dual thread work by the 64-bit machine, but those items will be addressed if and when I create a "how-to" about this effort.)

Next, I waited for the first completion of q range on the 64-bit machine to see what percentage was completed. I used this info to calculate how high the q should get if left alone to 100%. I then used this value to adjust each of the other machines to work above this value and separate from each other, by editing the test.job.T0 and test.job.resume files. Then I started Aliqueit with the -e switch on each 32-bit machine.

As each machine completed a cycle and created test.dat, I removed it to a holding area where I concatenated all of them into spairs.add. I then placed spairs.add into the 64-bit ggnfs_##... directory.

All seemed to work well, but the 64-bit machine needed to go back out several times for 1000000 more relations. It ended up needing to get to 113.9% of the original estimate. Is there a way I can tell if this is due to the added relations being no good, or if this is just due to an underestimate in the 64-bit machine's factmsieve.py script?

I realize that I can just run gnfs-lasieve with the same results, but I'm exploring whether this might be an easier way for those that may not want to go the gnfs-lasieve route...

Thanks for any comments...
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