20171024, 10:38  #1 
Jul 2005
2·7·13 Posts 
why DC credit can be so different
Hi,
I've notice in the current cat1 DC Range (about 41.6  41.7 mill) that usually I get about 63.x GHzDays credit but sometimes 61.x GHz Days. Example: Code:
41715517 C  Verified 20171024 04:11 2.5 EB1DAE6DFFDC3E75 63.6741 41714069 C  Verified 20171023 18:16 2.3 3E613C73FBFDB0B5 61.484 41712071 C  Verified 20171023 17:06 2.6 3129BFD8229F268E 63.6688 Last fiddled with by rudi_m on 20171024 at 10:39 
20171024, 12:09  #2 
Sep 2003
2589_{10} Posts 

20171024, 13:14  #3 
Jun 2003
12474_{8} Posts 
Are these on the same machines? AVX vs AVX2 (FMA3) can sometimes have different FFTs.

20171024, 16:12  #4 
Jul 2005
10110110_{2} Posts 
Ok thank you both. Seems that the last used implementation has influence on the credits, see the logs below (all from the same machine).
Code:
[Work thread Oct 15 22:19] Starting primality test of M41663449 using FMA3 FFT length 2240K, Pass1=448, Pass2=5K, clm=2, 3 threads [Work thread Oct 15 23:10] Resuming primality test of M41663449 using FMA3 FFT length 2240K, Pass1=448, Pass2=5K, clm=2, 3 threads [Work thread Oct 16 20:10] Resuming primality test of M41663449 using FMA3 FFT length 2240K, Pass1=448, Pass2=5K, clm=2, 3 threads [Comm thread Oct 17 13:34] CPU credit is 61.4102 GHzdays. [Work thread Oct 17 13:34] Starting primality test of M41689003 using FMA3 FFT length 2240K, Pass1=448, Pass2=5K, clm=2, 3 threads [Work thread Oct 17 13:44] Resuming primality test of M41689003 using FMA3 FFT length 2240K, Pass1=448, Pass2=5K, clm=2, 3 threads [Work thread Oct 18 05:48] Resuming primality test of M41689003 using FMA3 FFT length 2304K, Pass1=384, Pass2=6K, clm=2, 3 threads [Work thread Oct 19 02:48] Resuming primality test of M41689003 using FMA3 FFT length 2240K, Pass1=448, Pass2=5K, clm=2, 3 threads [Comm thread Oct 19 03:06] CPU credit is 61.4479 GHzdays. [Work thread Oct 19 03:06] Starting primality test of M41699461 using FMA3 FFT length 2240K, Pass1=448, Pass2=5K, clm=2, 3 threads [Work thread Oct 19 12:27] Resuming primality test of M41699461 using FMA3 FFT length 2240K, Pass1=448, Pass2=5K, clm=2, 3 threads [Work thread Oct 20 05:31] Resuming primality test of M41699461 using FMA3 FFT length 2304K, Pass1=384, Pass2=6K, clm=2, 3 threads [Comm thread Oct 20 17:38] CPU credit is 63.6496 GHzdays. [Work thread Oct 20 17:38] Starting primality test of M41706887 using FMA3 FFT length 2304K, Pass1=384, Pass2=6K, clm=2, 3 threads [Work thread Oct 21 02:31] Resuming primality test of M41706887 using FMA3 FFT length 2240K, Pass1=448, Pass2=5K, clm=2, 3 threads [Work thread Oct 21 23:31] Resuming primality test of M41706887 using FMA3 FFT length 2304K, Pass1=384, Pass2=6K, clm=2, 3 threads [Comm thread Oct 22 07:20] CPU credit is 63.6609 GHzdays. [Work thread Oct 22 07:20] Starting primality test of M41714069 using FMA3 FFT length 2304K, Pass1=384, Pass2=6K, clm=2, 3 threads [Work thread Oct 22 20:31] Resuming primality test of M41714069 using FMA3 FFT length 2304K, Pass1=384, Pass2=6K, clm=2, 3 threads [Work thread Oct 23 17:31] Resuming primality test of M41714069 using FMA3 FFT length 2240K, Pass1=448, Pass2=5K, clm=2, 3 threads [Comm thread Oct 23 20:16] CPU credit is 61.4848 GHzdays. Also Pass1=384 is also always about 34% faster than Pass1=448 for this machine. So it seems that the new benchmark mechanism does not really help to improve things in my case. In summary, It happens that I need 34% more time to finish an exponent and I will also get another penalty of 3.5% less credits. :( Last fiddled with by rudi_m on 20171024 at 16:13 
20171024, 18:02  #5  
P90 years forever!
Aug 2002
Yeehaw, FL
3·11·13·19 Posts 
Quote:
Quote:
You might be able to edit the gwnum.txt file so that the 2240K FFT is never selected. Last fiddled with by Prime95 on 20171024 at 18:03 

20171025, 01:08  #6 
Undefined
"The unspeakable one"
Jun 2006
My evil lair
6,679 Posts 
To my mind, regardless of the FFT length, when testing the same number we have done the same amount of useful work, and thus should be credited with the same amount of shagging rights. Note that I said "useful work", not simply "work". I could set myself a 32M FFT length and work on a 42M exponent. I'd get a lot more credit (if I had an account) than someone using a 2240K FFT length but most of the work is redundant/wasted. Do we really want to reward wasted effort?
Last fiddled with by retina on 20171025 at 01:09 
20171025, 03:42  #7  
Serpentine Vermin Jar
Jul 2014
5×677 Posts 
Quote:
I'm just guessing that the credit difference takes into account the difference in periteration times for the different FFT sizes so that it essentially makes it a "time taken" credit? 

20171025, 05:07  #8 
Undefined
"The unspeakable one"
Jun 2006
My evil lair
6,679 Posts 
In the OPs case above, the two FFTs (2304k and 2240k) have similar run times, and do the same amount of useful work, but the OP sees different credit.
Last fiddled with by retina on 20171025 at 05:10 
20171025, 11:13  #9 
Jun 2003
5436_{10} Posts 

20171025, 13:08  #10  
Jul 2005
182_{10} Posts 
It's 3% less credits plus 3% longer run time. Maybe the most interesting part is that the larger FFT length can be the faster one at all. I've never seen that before.
Quote:
To make this a bit better I've set now gwnum.txt to BenchWorkers=1 BenchCores=3 .. as this is what I'm also using in practice in local.txt: WorkerThreads=1 CoresPerTest=3 I would have expected that the default BenchCores should be the same like CoresPerTest. Good Idea, actually I could merge all my gwnum.txt files from all similar machines. This would even save some benchmark time. 

20171025, 13:46  #11 
"Forget I exist"
Jul 2009
Dartmouth NS
8418_{10} Posts 

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