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Old 2017-12-17, 17:40   #1
heliosh
 
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Default Which job for very slow machines?

When I set my Atom D2700 to "what make sense" I get a D-LL, which doesn't make sense because a job would take about a year. So i let it do PM1-L (It even found a factor! https://www.mersenne.org/report_expo...xp_lo=84476921 ) which takes about 9 days per exponent.
So, what would really make sense? I've never tried PRP-CF or ECM.
The computer is always on and since it doesnt support speed step it almost doesn't make a difference on energy consumption whether it is running at 100% load or idle.

Could even a raspberry pi be good for anything?
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Old 2017-12-17, 17:56   #2
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Quote:
Originally Posted by heliosh View Post
When I set my Atom D2700 to "what make sense" I get a D-LL, which doesn't make sense because a job would take about a year. So i let it do PM1-L (It even found a factor! https://www.mersenne.org/report_expo...xp_lo=84476921 ) which takes about 9 days per exponent.
So, what would really make sense? I've never tried PRP-CF or ECM.
The computer is always on and since it doesnt support speed step it almost doesn't make a difference on energy consumption whether it is running at 100% load or idle.

Could even a raspberry pi be good for anything?
Consider TF-LMH or PRP-CF for that machine.

I am using mlucas with my Raspberry PI 3 (and Gentoo Linux 64 bit). A single DC exponent is done in about 1.5 months. But I am addicted to GIMPS since 1987...

Last fiddled with by ET_ on 2017-12-17 at 18:00
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Old 2017-12-17, 17:56   #3
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Quote:
Originally Posted by heliosh View Post
Could even a raspberry pi be good for anything?
It is certainly a good factoring engine, though perhaps not for the GIMPS fraternity (I've no experience there). It runs GMP-ECM very nicely and will also talk to ECMNET servers --- at least, mine does.
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Old 2017-12-17, 17:57   #4
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Quote:
Originally Posted by heliosh View Post
When I set my Atom D2700 to "what make sense" I get a D-LL, which doesn't make sense because a job would take about a year. So i let it do PM1-L (It even found a factor! https://www.mersenne.org/report_expo...xp_lo=84476921 ) which takes about 9 days per exponent.
So, what would really make sense? I've never tried PRP-CF or ECM.
The computer is always on and since it doesnt support speed step it almost doesn't make a difference on energy consumption whether it is running at 100% load or idle.

Could even a raspberry pi be good for anything?
I would stick with P-1 on the Atom, and consider running Mlucas on the Pi -- if Mlucas is now working on such computers -- although doing bleeding edge Mersenne tests is going to take a long time.

Last fiddled with by paulunderwood on 2017-12-17 at 17:58
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Old 2017-12-18, 04:29   #5
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Quote:
Originally Posted by ET_ View Post
I am using mlucas with my Raspberry PI 3 (and Gentoo Linux 64 bit). A single DC exponent is done in about 1.5 months. But I am addicted to GIMPS since 1987...
Luigi, how many exponents do you run in parallel on your (IIRC) 20-core Pi? One per 4-core subset?

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I would stick with P-1 on the Atom, and consider running Mlucas on the Pi -- if Mlucas is now working on such computers -- although doing bleeding edge Mersenne tests is going to take a long time.
Mlucas has always been buildable in generic-C-code mode on Pi and such - the main thing that has changed in the past few months is that I released a version with inline-asm targeting the ARM v8 128-bit SIMD instruction set. See the related thread in the Software -> Mlucas subforum. (Page 11 of the thread is where the release is announced and timings form users on a variety of ARMv8 arches follow.) The gain from the SIMD code on ARMv8 is modest compared to (say) te SSE2 code running on my Core2 system, which I believe to be due to the x86 family having dedicated hardware-arithmetic functional units for SIMD versus scalar (64-bit-double for the former, 80-bit for the latter), compared to the low-power-optimized ARM having both scalar and SIMD instructions share a common set of functional units. (Someone please correct me if my surmise here is incorrect.)
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Old 2017-12-18, 09:37   #6
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Luigi, how many exponents do you run in parallel on your (IIRC) 20-core Pi? One per 4-core subset?
Correct, but actually I am only running on 3 boards. I am adding another small fan to the "cube", as thermal issues prevent me to run all 5 boards together
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Old 2017-12-18, 09:55   #7
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Raspberry pi 3 (and anything else with an A53 chip) seems a good "minimum recommended hardware" watermark for mlucas, boards with older chipsets are probably best suited to something like factoring. I tried mlucas on an A7 but it didn't seem worth it.

If you have a raspberry pi 3 and want to use mlucas, me and ET have successfully tried it with this distro.
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Old 2018-01-15, 02:13   #8
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I try run George Woltman's Prime95 program (a.k.a. mprime for the linux version) in a Raspberry pi 3 with gentoo-on-rpi3-64bit and not works: "mprime cannot execute binary file: Exec format error".

Its only possible run mlucas on Raspberry pi 3 ?


Quote:
Originally Posted by M344587487 View Post
Raspberry pi 3 (and anything else with an A53 chip) seems a good "minimum recommended hardware" watermark for mlucas, boards with older chipsets are probably best suited to something like factoring. I tried mlucas on an A7 but it didn't seem worth it.

If you have a raspberry pi 3 and want to use mlucas, me and ET have successfully tried it with this distro.
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Old 2018-01-15, 07:22   #9
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Originally Posted by thiagoarreguy View Post
I try run George Woltman's Prime95 program (a.k.a. mprime for the linux version) in a Raspberry pi 3 with gentoo-on-rpi3-64bit and not works: "mprime cannot execute binary file: Exec format error".

Its only possible run mlucas on Raspberry pi 3 ?
Yes.
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Old 2018-01-15, 11:43   #10
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If a very slow machine used very little electricity and cost very little, then potentially every job could be for it. As long as it's not so utterly slow that you can't get enough useful work out of it before newer, more efficient technology gets invented.

I don't know if any of the current crop of ARM machines or Atom machines fit the bill. I suspect not, at least not yet.
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Old 2018-01-15, 12:32   #11
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Quote:
Originally Posted by GP2 View Post
I don't know if any of the current crop of ARM machines or Atom machines fit the bill. I suspect not, at least not yet.
Unless they're running anyway. My atom doesn't support speedstep; the difference at the socket is only about 3W between idle and 100% PRP.
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