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Old 2016-04-19, 12:19   #1
Johnatan
 
Apr 2016

1310 Posts
Default yafu memory usage for ecm

My 16GB RAM machine started to swap while performing ECM.

I see that GMP-ECM has parameter to limit memory usage for stage 2
Quote:
-maxmem n use at most n MB of memory in stage 2
Is there a similar option available for yafu?
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Old 2016-04-19, 13:13   #2
bsquared
 
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"Ben"
Feb 2007

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No... yafu is not a full wrapper of all gmp-ecm functionality.
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Old 2016-04-19, 14:50   #3
VBCurtis
 
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"Curtis"
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Quote:
Originally Posted by Johnatan View Post
My 16GB RAM machine started to swap while performing ECM.
How many threads of ECM were running? What B1 bound was Yafu using? How big is the input number?

You have to run some awfully big curves (or really really big composites, like over 500 digits) for ECM to use enough memory to swap. For example, curves with B1 = 110M use under 1GB per thread while in stage 2, though that does scale with input size; for inputs under 250 digits, you should be under 1GB/thread at that bound (which is the default to find factors of 55 digits in size). t60 curves of B1 = 260M should be under 2GB/thread, still easily fitting in your memory space unless you have a shiny modern Xeon.
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Old 2016-04-19, 18:11   #4
Johnatan
 
Apr 2016

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Yes, the modulus is big. I am factoring C614. I have 8 cores.

Is there some easy hack how I can pass maxmem param to ECM?

Last fiddled with by Johnatan on 2016-04-19 at 18:12
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Old 2016-04-19, 19:30   #5
bsquared
 
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Well... I just thought of this. No idea if it will work.

Beyond a certain B1 (50k, I think) yafu works by executing a system command to use an external ecm binary, and then parses a temporary results file.

You could replace the "ecm_path=<path>" line in yafu.ini with the path to a script that calls the ecm binary with whatever additional arguments you want. The script should also handle the arguments that yafu provides (yafu builds the following system command: "echo your_number | <ecm_path> -sigma sigma B1 > temp.out")

Last fiddled with by bsquared on 2016-04-19 at 19:33
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Old 2016-06-13, 11:28   #6
Johnatan
 
Apr 2016

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Thank you! This method for passing flags to GMP-ECM works fine!
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