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Old 2010-04-15, 18:49   #8
Apr 2010

33 Posts

Originally Posted by garo View Post
lycorn has made a reasonable suggestion. It might be overkill to set all 6 cores to do P-1 - though there is no reason not to particularly since we are always short of P-1 testers. 300MB is a good amount for 53M tests that are being done today. 500MB is better. After that the marginal gains with every extra MB of RAM get smaller. George's recommendation from the readme.txt is
50000000 85MB 170MB 250MB
for a 50M the min, reasonable and desirable memory.

Also since the max memory is only used during stage 2, you can limit the number of threads that do stage 2 at any one time.
This will stagger your stage 2s and when the number of workers doing stage 2 reaches the limit, additional workers will skip stage 2 and do stage 1 on subsequent exponents before returning to do stage 2 when the memory becomes free. If six cores are doing P-1, you could get by with setting MaxHighMemWorkers=4 and still achieve maximal throughput. So you really could get by with only 1GB of RAM and 6 P-1s if you needed to.

If you do real work with the computer during the day you may want to set different amounts of memory available to the computer during the day and night. And set Prime95 to only do stage2 when max memory is available with this switch:
Thanks garo for the suggestion. I actually don't want this to run P-1 factoring test only but I want it to primarily run LL test but the assignment from the server may require a P-1 test performed first so that is why I'm interested in RAM requirements. I would like to give mprime the best chance of finding a factor and avoid having to run a pointless LL test.

Here is what I think I'll do. I'll install 2GB of RAM and run mprime under Ubuntu Server 64bit. I'll allocate 1800MB of RAM for testing and then use:


That way the full RAM is available to each Stage 2 test and has the best opportunity for finding a factor and avoiding a useless LL test.

Garo forgot to mention that the above parameters should be placed in local.txt

What do you all think. Is this a good idea?

I'm currently testing this on a Duo system with only 1 core running stage 2 tests and 2GB allocated. I'll time how long a full P-1 prime test will take with more ram allocated. It should take longer because the stage 2 would scan a longer range.
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