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Old 2021-08-27, 19:07   #18
EdH's Avatar
"Ed Hall"
Dec 2009
Adirondack Mtns

32×457 Posts

Originally Posted by VBCurtis View Post
Well, the reason we control either stage1 or stage2 norms from the command line is because msieve's defaults are from the era before GPUs, while GPUs produce 50-100x more data from stage1.

So, if you're running CPU only, I'd relax stage1 norm to half of default, or maybe even default. That should yield enough raw polys for size-opt to have useful work to do.
But, my problem was that I was piling up too many hits from stage 1 - several hundred thousand in five minutes. Maybe I really needed to restrict stage 1 via its norm, but leave stage 2 default in place.

Another query: I'm engaging all the threads of my machines via a script and providing the ranges via the script. I find that many ranges quit almost immediately with no results and those that continue always have the same coefficients. I thought that Msieve chooses random coefficients within the given range. Is the randomness only in the multiple of the small primes? And, does this mean if the ranges are too small, there will be no appropriate coefficients within some? I've written my script to take these skipped instances into account when assigning threads.

Additionally, once Msieve has chosen a coefficient within a range, it never releases that coefficient to move to another.* Should I choose ranges based on expecting each to hold only one appropriate coefficient, perhaps 120120 (2^3*3*5*7*11*13), which has been the first coefficient for every run?

I know Msieve README.nfs says each range can be run on multiple machines and the randomness will minimize collisions, maybe my understanding of randomness is(was) incorrect and two machines (threads) will work the same coefficient, but the randomness is in the work within that coefficient. Am I learning or losing it?

* I'm guessing that's because of the "deadline: 8640000 CPU-seconds per coefficient" and it really would move on after a few months.
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