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2021-10-09, 22:09   #573
rogue

"Mark"
Apr 2003
Between here and the

11×619 Posts

Quote:
 Originally Posted by pepi37 If I use srsieve2 to sieve k*10^n-1 why is reported k*10^n+c? Maybe it is just simple error, or something deeper?
Missing a % in a format string. It should be "%+c" and is just "+c" in the code. I have fixed and committed that fix.

Last fiddled with by rogue on 2021-10-09 at 22:11

 2021-10-11, 17:48 #574 matzetoni     Feb 2019 9710 Posts Code: >> gfndsieve.exe -k5000000 -K6000000 -n16001 -N17000 -o"out_test.txt" gfndsieve v2.0, a program to find factors of k*2^n+1 numbers for variable k and n Sieve started: 3 < p < 2^62 with 500000000 terms (5000001 <= k <= 5999999, 16001 <= n <= 17000, k*2^n+1) Fatal Error: Invalid factor: 5006169*2^16953+1 mod 5012429 = 2651427 I got this error when using mtsieve_2.2.1 There is no error when using the same command with mtsieve_2.0.3
2021-10-11, 19:12   #575
rogue

"Mark"
Apr 2003
Between here and the

152318 Posts

Quote:
 Originally Posted by matzetoni Code: >> gfndsieve.exe -k5000000 -K6000000 -n16001 -N17000 -o"out_test.txt" gfndsieve v2.0, a program to find factors of k*2^n+1 numbers for variable k and n Sieve started: 3 < p < 2^62 with 500000000 terms (5000001 <= k <= 5999999, 16001 <= n <= 17000, k*2^n+1) Fatal Error: Invalid factor: 5006169*2^16953+1 mod 5012429 = 2651427 I got this error when using mtsieve_2.2.1 There is no error when using the same command with mtsieve_2.0.3
I will look into this.

2021-10-11, 21:46   #576
ET_
Banned

"Luigi"
Aug 2002
Team Italia

484810 Posts

Quote:
 Originally Posted by matzetoni Code: >> gfndsieve.exe -k5000000 -K6000000 -n16001 -N17000 -o"out_test.txt" gfndsieve v2.0, a program to find factors of k*2^n+1 numbers for variable k and n Sieve started: 3 < p < 2^62 with 500000000 terms (5000001 <= k <= 5999999, 16001 <= n <= 17000, k*2^n+1) Fatal Error: Invalid factor: 5006169*2^16953+1 mod 5012429 = 2651427 I got this error when using mtsieve_2.2.1 There is no error when using the same command with mtsieve_2.0.3
Are you working on Fermat factors research?

 2021-10-22, 16:54 #577 rogue     "Mark" Apr 2003 Between here and the 11×619 Posts I have posted mtsieve 2.2.2 over at sourceforge. It addresses the open issues and has these changes: Code:  framework: Added __attribute__ to method declarations that accept variable arguments. srsieve2, srsieve2cl: version 1.5.3 Modified to not remove terms that are prime as that defeats the purpose of Sierpinski/Riesel searches. Fixed bug where maxn for a sequence has a small factor, but it is not found. gnfdsieve, gfndsievecl: version 2.1 Fixed bug where code can find invalid factors.
2021-10-23, 09:30   #578
ET_
Banned

"Luigi"
Aug 2002
Team Italia

24×3×101 Posts

Quote:
 Originally Posted by rogue I have posted mtsieve 2.2.2 over at sourceforge. It addresses the open issues and has these changes: Code:  framework: Added __attribute__ to method declarations that accept variable arguments. srsieve2, srsieve2cl: version 1.5.3 Modified to not remove terms that are prime as that defeats the purpose of Sierpinski/Riesel searches. Fixed bug where maxn for a sequence has a small factor, but it is not found. gnfdsieve, gfndsievecl: version 2.1 Fixed bug where code can find invalid factors.
Can Linux users acess to the source code and recompile?

2021-10-23, 14:06   #579
rogue

"Mark"
Apr 2003
Between here and the

11·619 Posts

Quote:
 Originally Posted by ET_ Can Linux users acess to the source code and recompile?
All of the source is on sourceforge as well as a makefile that works on OS X and Windows. If the makefile doesn't work on Linux, I would not expect it to be difficult to get it to work.

2021-10-23, 16:13   #580
ET_
Banned

"Luigi"
Aug 2002
Team Italia

24×3×101 Posts

Quote:
 Originally Posted by rogue All of the source is on sourceforge as well as a makefile that works on OS X and Windows. If the makefile doesn't work on Linux, I would not expect it to be difficult to get it to work.
Thank you Mark. I will look for it better.

 2021-10-25, 15:56 #581 ryanp     Jun 2012 Boulder, CO 1101001112 Posts Is there advice about how to best choose values for "-G", "-g" and "-W' for OpenCL based programs like srsieve2cl on a given GPU? On a Tesla A100, I couldn't get srsieve2cl to go much above 9 to 10M p/sec, after fiddling with values for a while. By comparison, a plain ./srsieve2 -W 48 on a 72-core Xeon CPU gives me about 15M p/sec.
2021-10-25, 16:24   #582
rogue

"Mark"
Apr 2003
Between here and the

11×619 Posts

Quote:
 Originally Posted by ryanp Is there advice about how to best choose values for "-G", "-g" and "-W' for OpenCL based programs like srsieve2cl on a given GPU? On a Tesla A100, I couldn't get srsieve2cl to go much above 9 to 10M p/sec, after fiddling with values for a while. By comparison, a plain ./srsieve2 -W 48 on a 72-core Xeon CPU gives me about 15M p/sec.
I recommend bumping -g. You will have to play around to see where you start seeing diminishing returns.

I have noticed that when running many workers that the code that feeds the worker threads is not fast enough. In some cases it is better to have multiple instances of srsieve2 running. To address this would require significant changes to the framework.

2021-10-25, 16:39   #583
ryanp

Jun 2012
Boulder, CO

32×47 Posts

Quote:
 Originally Posted by rogue I recommend bumping -g. You will have to play around to see where you start seeing diminishing returns. I have noticed that when running many workers that the code that feeds the worker threads is not fast enough. In some cases it is better to have multiple instances of srsieve2 running. To address this would require significant changes to the framework.
I've tried a number of combinations of -G and -g, ranging from "-g 16" up to "-G 8 -g 288". No matter what, it always tops out around 9.7 or 9.8M p/sec.

This is pretty surprising (the A100 has a max 19.5 TFlop/s single precision) considering I can easily get higher than that with 48 workers on a Xeon.

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