mersenneforum.org how to assign all cores to one project
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 2019-12-04, 15:05 #1 keysarecool   Mar 2019 2·7 Posts how to assign all cores to one project Please pardon my question as I did several searches but found nothing. I am trying to assign all 18 cores to one prime. Currently, it is trying to find 5 different primes and with a distribution of cores as listed: 4c x3 and 3c x2. I would like to search for each prime with all 18 cores one at a time. How do I force it to reassign it and then manually put it back on the remaining 4 primes without losing months of work?
 2019-12-04, 16:42 #2 petrw1 1976 Toyota Corona years forever!     "Wayne" Nov 2006 Saskatchewan, Canada 105538 Posts If you are using Prime95 on Windows I can answer. On the top menu bar click: Test... Stop (All workers) Test... Worker Windows... Number of Worker Windows to Run: 1 CPU cores to user (multithreading): 18 Test.. Exit Edit your worktodo.txt to place all assignments under [Worker #1] Restart Prime95 You won't lose any work. But your total throughput will drop...maybe 25-50%. For example if running 18 assignments on 1 core each can finish each assignment in 18 days. Running 1 assignment on 18 cores may take 2 to 4 days. Run the following for an analysis on the impact of various core groupings: Options... Benchmark
2019-12-04, 17:10   #3
storm5510
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Aug 2009
U.S.A.

32×11×17 Posts

Quote:
 Originally Posted by keysarecool Please pardon my question as I did several searches but found nothing. I am trying to assign all 18 cores to one prime. Currently, it is trying to find 5 different primes and with a distribution of cores as listed: 4c x3 and 3c x2. I would like to search for each prime with all 18 cores one at a time. How do I force it to reassign it and then manually put it back on the remaining 4 primes without losing months of work?
In my experience, Prime95, has never used more than 50% of any CPU's capability. You may be wasting your time and effort. Running multiple instances, which you can, is a different story, but not on the same exponent.

2019-12-04, 17:29   #4
petrw1
1976 Toyota Corona years forever!

"Wayne"
Nov 2006

10001011010112 Posts

Quote:
 Originally Posted by storm5510 In my experience, Prime95, has never used more than 50% of any CPU's capability. You may be wasting your time and effort. Running multiple instances, which you can, is a different story, but not on the same exponent.
This is true if you have a hyperthreaded CPU (which most are nowadays).
A non-hyperthreaded (Intel i5 for example) will still use 100% of each CPU...because they are all physical.

OP: If you can ran a Benchmark and analyze the results you will probably find that if you want to finish assignments quicker without sacrificing too my throughput, that a good middle ground might be running something between 3 worker with 6 cores or 6 workers with 3 cores each.

 2019-12-04, 21:21 #5 keysarecool   Mar 2019 168 Posts Thanks, some clarification is in order I believe. I am not hyperthreading the cores as my understanding is that it does no good to do so. If there is no gain to using multiple cores (Physically 18) why would Prime95 default to that for every assignment? I am a bit confused here and looking to speed up the process as much as possible. I really do appreciate the assistance. Oh and it is running on Windows 10 Enterprise. Last fiddled with by keysarecool on 2019-12-04 at 21:21
 2019-12-04, 21:34 #6 Uncwilly 6809 > 6502     """"""""""""""""""" Aug 2003 101×103 Posts 23×1,109 Posts There are gains and losses for using different core combinations. If you want to check a reported prime as fast as possible, sure use 18 all on one task. If you are trying to get the most number of candidates tested in a year, more tasks. About 3 cores per task is the sweet spot of speed of each task and total through-put. Most folks like to see things click along. More cores per task helps that.
 2019-12-04, 21:36 #7 keysarecool   Mar 2019 2·7 Posts Ok, where do I set the cores per task. I tried to put everything under the single worker and all it did was download more tasks. Once again thank you for all of the help.
2019-12-04, 21:44   #8
petrw1
1976 Toyota Corona years forever!

"Wayne"
Nov 2006

73·13 Posts

Quote:
 Originally Posted by keysarecool Thanks, some clarification is in order I believe. I am not hyperthreading the cores as my understanding is that it does no good to do so. If there is no gain to using multiple cores (Physically 18) why would Prime95 default to that for every assignment? I am a bit confused here and looking to speed up the process as much as possible. I really do appreciate the assistance. Oh and it is running on Windows 10 Enterprise.
I can't speak for why Prime95 would default to 18 cores.
As Uncwilly said; if you want 1 assignment to finish as fast as possible then run 1 assignments with all 18 cores.
If you want to complete the most assignments in a longer period of time (months or years) then run multiple assignments at a time: 18 with 1 core each or 9 with 2 cores or 6 with 3 cores.

Again the benchmark task will be able to tell you the most effective combination.
There are way more learned computer people here but basically with that many cores the bottleneck may be in the Cache or RAM or Inter-Core communication and lots of other things I cannot speak of with assurance.

That is why 6 assignments with 3 cores "may be" more efficient than 18 with 1 each.

2019-12-04, 21:45   #9
petrw1
1976 Toyota Corona years forever!

"Wayne"
Nov 2006

73·13 Posts

Quote:
 Originally Posted by keysarecool Ok, where do I set the cores per task. I tried to put everything under the single worker and all it did was download more tasks. Once again thank you for all of the help.
From my 1st post here:

Code:
On the Prime95 top menu bar click:
Test...
Stop (All workers)

Test...
Worker Windows...
Number of Worker Windows to Run: 1
CPU cores to use (multithreading): 18
… OR … 2 and 9 ...OR.... 3 and 6
as long as they add up to all 18 cores.

Test..
Exit

Edit your worktodo.txt and divide your assignments under as many workers [Worker #x] as specified above.

Restart Prime95
You might get more tasks based on the calculated number required for the days of you work you are requesting.
But they should still all be under "The Number of Workers..." workers.

Last fiddled with by petrw1 on 2019-12-04 at 21:50 Reason: clarification

 2019-12-04, 21:48 #10 keysarecool   Mar 2019 1410 Posts I found it, it was told to run 5 worker windows. I changed it to one. Lets see how long it says it will take now. Thank you!
 2019-12-04, 21:50 #11 Uncwilly 6809 > 6502     """"""""""""""""""" Aug 2003 101×103 Posts 100010101010002 Posts To set the number of cores per worker and task do as Petrw1 said in the post near the top. You have to set the number of cores for each worker separately. Make sure to not over assign cores (19 on an 18 core system). I have attached where you can make changes to the individual workers. It grabbed more assignments at the same time it shed others. Like Petrw1 said to edit the worktodo. Since Prime95 deleted the assignments for all of the other workers it did not move them over to the section for worker 1. Worker 1 then did not have enough tasks for the number of days that you have asked to have work stored up for. Therefore it grabbed more tasks. Attached Thumbnails

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