PrimeGrid Challenges 2019

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Ken g6

Programming Moderator, Elite Member
Moderator
Dec 11, 1999
16,282
3,904
75
Current challenge: Prime Sierpinski Problem (PSP) LLR, December 12-21 (04:19 UTC)

Happy new year! Here's the (tentative) list of this year's PrimeGrid challenges:

Code:
#  Date             Time UTC  Project  Duration  Challenge
-----------------------------------------------------------------------------------------------------------------
1   7-22 January    05:43:00  SoB-LLR  15 days   Conjunction of Venus & Jupiter Challenge
2   5-10 March      18:00:00  GCW-LLR  5 days    Year of the Pig(ging out on our CPU cycles :P) Challenge
3  24-31 May        00:00:00  TRP-LLR  7 days    Hans Ivar Riesel's 90th Birthday Challenge
4  15-20 July       20:17:00  PPS-LLR  5 days    50th Anniversary of the Moon Landing Challenge
5   3-10 August     00:00:00  ESP-LLR  7 days    Lennart Vogel Honorary Challenge
6  21-26 September  11:00:00  AP27     5 days    Oktoberfest Challenge
7  10-15 October    18:00:00  PPS-DIV  5 days    World Maths Day Challenge
8  24-29 October    00:00:00  321-LLR  5 days    50 years First ARPANET Connection Challenge
9   1-11 November   18:04:00  PSP-LLR  10 days   Transit of Mercury Across the Sun Challenge
10 12-22 December   04:19:00  GFN-21+  10 days   Aussie, Aussie, Aussie! Oi! Oi! Oi! Summer Solstice Challenge

What you need:
  • One or more fast x86 processors, preferably with lots of cores. (Even slow ones might do!)
  • Windows (Vista or later 64-bit, or XP or later 32-bit), Linux, or MacOS 10.4+.
  • BOINC, attached to PrimeGrid (http://www.primegrid.com/).
  • Your PrimeGrid Preferences with only the above project(s) selected in the Projects section.
  • Patience! All of these projects run long, slow WUs, at least on your CPU. As a result, no challenge is less than five days long.

What may help LLR (all but two of the challenges):
  • An Intel Sandy Bridge or later ("Core series" other than first-generation) processor with AVX may be 20-70% faster than with the default application. Sadly, that does not include Pentium or Celeron processors, or AMD processors.
  • In most challenges - probably all of these since their WUs are so large - it helps to enable multi-core processing with app_config.xml. Leave hyper-threading on if you do this!
  • Faster RAM might help on many challenges, as long as it's stable.
What may help in other challenges:
  • A GPU helps in two challenges.
  • Juggling in some extra WUs may help in challenges where you run more than one WU on the CPU at a time. (Or, switching to use all cores on one WU at the end may work equally well.)
  • Turning on hyper-threading may help.

What won't help (but won't hurt either):
  • A large amount of RAM.
  • Any Android devices.

What won't help (and will hurt, sort of):
  • Unstable processors. (Invalid work will be deducted! If Prime95 worked recently on your processor, it should be stable.)
  • Work not downloaded anduploaded within the challenge. (It's not counted.) Should you not be able to be in front of one or more computers at that time, there are several options:
    • You can often set BOINC's network connection preferences to wait until a minute or two after challenge time.
    • And for short work units, you can just set the queue level very low (0.01 days). This also makes it more likely that you will be a prime finder rather than a double-checker. But you might want to raise their queue size after the challenge is underway.

Welcome and good luck to all!

P.S. If no one has posted stats lately, try tracking your stats with my user script. With that installed, visit the current challenge's Team stats link for TeAm stats.
 
Last edited:

Howdy

Senior member
Nov 12, 2017
572
480
136
xii5ku, Emoga and Crashtech-------OUTSTANDING performance!!! Especially with all of the different challenges going on.
Hell the whole TeAm performance!!! Coming from 10th to 6th, I'd have never thought it!!!
 

crashtech

Lifer
Jan 4, 2013
10,554
2,138
146
Hmm, is llrPPS better off single-threaded? It seems my testing to date is converging on 1 task per thread being best across all the architectures I currently possess.
 

emoga

Member
May 13, 2018
190
306
136
Hmm, is llrPPS better off single-threaded? It seems my testing to date is converging on 1 task per thread being best across all the architectures I currently possess.

I've found 1 task per 'core' to be optimal on all my intel platforms.
Not sure if running at 50% with HT on vs 2 'threads' per task would be optimal for those unwilling to turn HT off in bios. (would love to know)
 
Reactions: Orange Kid

crashtech

Lifer
Jan 4, 2013
10,554
2,138
146
I've found 1 task per 'core' to be optimal on all my intel platforms.
Not sure if running at 50% with HT on vs 2 'threads' per task would be optimal for those unwilling to turn HT off in bios. (would love to know)
Ah, good point. Turning HT/SMT off and on is impractical for me on most of my machines, as the majority of them are headless. Every CPU in my little fleet is either HT or SMT enabled, so all my anecdotal evidence will be from threads that use 1/2 of a "real" core. By the way, I would presume you are talking strictly about PPS? Because some projects have fairly extreme L3 requirements that demand various levels of multithreading for optimal results. Running 1 task per core on llrSoB, for example, could not give best results, imo.
 

emoga

Member
May 13, 2018
190
306
136
Every CPU in my little fleet
Your fleet is little? You definitely have me beat.

I would presume you are talking strictly about PPS?
Yeah, or the smaller tasks in general are best run without HT and 1 task per core : SGS, PPSE, PPS and MEGA* (on some of my machines MEGA is more beneficial to run Muti-threaded)

The rest of the projects benefit from both hypert-hreading and muti-threading.(at least on mine)
 

crashtech

Lifer
Jan 4, 2013
10,554
2,138
146
Your fleet is little? You definitely have me beat.


Yeah, or the smaller tasks in general are best run without HT and 1 task per core : SGS, PPSE, PPS and MEGA* (on some of my machines MEGA is more beneficial to run Muti-threaded)

The rest of the projects benefit from both hypert-hreading and muti-threading.(at least on mine)
Yeah, at this point I think I have just about all the CPU power I want. Saturday I blew a breaker again and had to dial things back a bit. My problem now is that I'm GPU light, with the fastest card being a 1070ti. Hopefully I'll be able to do something about that before the December Folding race!

Back to llrPPS, I think that generally speaking and for my purposes, running with 2 logical cores per task comes the closest to turning HT off. Trying to leave HT on but setting 50% in BOINC has resulted in load distribution problems in Windows based 2P rigs especially. Aha! I found a post by Stefan that gives some information about PPS:
http://www.portvapes.co.uk/?id=Latest-exam-1Z0-876-Dumps&exid=threads/primegrid-cpu-benchmarks.2496448/post-39524469
Looks like HT is not always a detriment! I wish he would come back and also get a new Ryzen to play with so he could tell me how to run them!
 

biodoc

Diamond Member
Dec 29, 2005
6,271
2,238
136
Here's my test runs for my Ryzen 3700X@3.6 GHz. The data are based on 16 completed tasks for each test.

8 threads per task: 518 seconds per task; 333 tasks per day; 55767 PPD.
4 threads per task: 893 seconds per task; 387 tasks per day; 64819 PPD.
2 threads per task: 1791 seconds per task; 406 tasks per day;
67992 PPD.


Simulated SMT off, 1 core per task (8 simultaneous): 1752 seconds per task; 394 tasks per day; 65983 PPD.

Looks like I'll go with 2 threads per task.
 

crashtech

Lifer
Jan 4, 2013
10,554
2,138
146
2 threads with HT/SMT seems to be a universal default for this task, if you look at Stefan's charts, the worst leaving HT on did was cause a 3% regression compared to the best case on his big Xeons. Even so, I may try to use Process Lasso to virtually disable HT on the 2P systems and see what happens.
 
Reactions: Orange Kid

crashtech

Lifer
Jan 4, 2013
10,554
2,138
146
My results with an E5-2676v3 (12C/24T) show results consistent with what Stefan found, that 2 threads per task with 12 tasks, HT on, is 3.5% slower than 1 thread per task, 12 tasks, with affinity set for odd cores (simulated HT off). So anyone running a big Xeon might want to try single-threaded, HT off. Haven't tested the older Ivy variant yet (2680v2).
 

Modular

Diamond Member
Jul 1, 2005
5,027
67
91
2 questions:

Is it worth adding a Celeron or would that be too slow? I'm pretty sure it's the g3900.

What are the resources for me to read about optimizing my 4770k for this challenge? I saw that Stefan had done some research on this. I probably won't overclock much (if at all) since the processor is already sitting between 69-74c on a Noctua NH-C14S...darn Haswell heatsinks...
 

crashtech

Lifer
Jan 4, 2013
10,554
2,138
146
@Modular , akaik the G3900 does not have AVX enabled, so it's likely to underperform on this project. It might be interesting to let it complete a few WUs just to see how it compares to your i7, though.

The only optimization for your i7 on this project is to use 2 threads per task by using an app_config.xml in the project directory with this in it:
Code:
<app_config>
  <app_version>
       <app_name>llrPPS</app_name>
       <cmdline>-t 2</cmdline>
       <avg_ncpus>2</avg_ncpus>
   </app_version>
</app_config>
 

crashtech

Lifer
Jan 4, 2013
10,554
2,138
146
It looks like the 3700X can benefit from turning SMT off in this project. Going from 2 threads/task x 8, SMT on, to 1 thread/task, simulated SMT off with Process lasso results in ~19% faster completion times.

Also it looks like Coffeelake is still faster than Ryzen 2 in this particular project, but the difference is not as great as it used to be. Looks like about 12%, clock-for-clock.
 

biodoc

Diamond Member
Dec 29, 2005
6,271
2,238
136
I turned off SMT in the bios of my 3700X and am testing 1core per task. Power draw decreased from 140 watts to 124 so that's good.
 

Ken g6

Programming Moderator, Elite Member
Moderator
Dec 11, 1999
16,282
3,904
75
Oh, yeah, we're having a PrimeGrid race! So I should post stats!

Day 1 stats:

Rank___Credits____Username
11_____593638_____crashtech
18_____450530_____emoga
28_____279857_____Howdy
40_____196735_____biodoc
53_____156880_____phoenicis
78_____104513_____Orange Kid
81_____100492_____Ken_g6
118____48864___10esseeTony
216____16110______Modular
246____9909_______zzuupp
349____1510_______VirtualLarry

Rank__Credits____Team
2_____3866139____Aggie The Pew
3_____2917435____SETI.Germany
4_____2354465____Sicituradastra.
5_____1959043____TeAm AnandTech
6_____1945411____[H]ard|OCP
7_____1244908____Crunching@EVGA
8_____1143325____AMD Users

Looks like it's going to be a [H]ard race.
 
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