20060820, 04:58  #1 
Dec 2005
2×7 Posts 
Core2 X6800 Test Times
Based on the benchmarks it will take a Core2 X6800 2.9 MH about 17 days to LL test a 35,000,000 digit number. Can this computer test 2 numbers at once, thus testing 2 numbers in 17 days?

20060820, 05:13  #2 
Aug 2002
North San Diego County
2×11×31 Posts 
It will probably be more like 2 numbers in 18.5 days. Each number can run on its own core, but one cannot expect 100% linear scaling.

20060821, 20:50  #3 
Aug 2006
2·3 Posts 
On a X6800 Conroe in XP MCE here are some numbers:
With one instance of P95 at 2048 fft I was getting .041 sec per iteration. With one instance LL testing and one in P1 factoring I was getting .051 sec/iter. With two instances of P95 at 2048 fft I was getting .046 seconds/iteration. So 16.9 Days for One 10M digit LL test or 18.97 Days for two? Do these numbers sound right? Hope this helps. Zak 
20060824, 18:07  #4 
Dec 2005
2×7 Posts 
Those numbers sound great. I currently am running a P4 at 2.9Mh. I need to convince my wife it is time for an upgrade.

20060824, 19:03  #5 
Jul 2004
Potsdam, Germany
3×277 Posts 
I would be interested in gmpecm benchmarks of the Core2.
Does anybody care to run some curves with it? 
20060824, 20:49  #6 
Aug 2006
2·3 Posts 

20060826, 16:42  #7 
Jul 2004
Potsdam, Germany
3×277 Posts 
Thanks for your offer, Zak!
First, download the binaries from here. Unfortunately, there are no binaries for the Core2 yet. You could try those for the P4 (it should be quite irrelevant which specific, I guess) and/or the Athlon binaries. Then create a text file in the same directory, with the following contents: 512697074397868507464830992105855089664575695425522835992747470881488640052598076608364916264171931518711016452728463454015615930496173963179151714060127379851269343356435328168074844330850160596351576082971234903468258958205452547120425573322600440367004964883936437287906385278156561312381803353061 Afterwards, execute the program as follows: ecm 1000000 < [textFile] Where [textFile] is the name of the text file. It should run for 24 minutes. Please do this twice and report back the output. Compiling the sources would be best, but involves quite some manual work. Since this instruction, GMP and gmpecm have improved, you'd need GMP 4.2 and gmpecm 6.1.1 If you want to try it, I'm confident you'll get enough feedback from the forum to solve any problems in your way. Last fiddled with by Mystwalker on 20060826 at 16:43 
20060828, 03:21  #8 
Aug 2006
2·3 Posts 
Here are results from ECM
(Version I was able to compile)(Was saying stuff for pentium3 durring install?) GMPECM 6.1.1 [powered by GMP 4.2.1] [ECM] Input number is (300 digits) Using B1=1000000, B2=1045563762, polynomial Dickson(6), sigma=2996848946 Step 1 took 47390ms Step 2 took 18485ms (Version from forums for Prescott p4) GMPECM 6.1.1 [powered by GMP 4.2.1] [ECM] Input number is (300 digits) Using B1=1000000, B2=1045563762, polynomial Dickson(6), sigma=1801303844 Step 1 took 41703ms Step 2 took 17109ms Tests done on Core 2 Duo X6800 with With 4 GB Ram. Hope This helps. Zak 
20060828, 19:20  #9 
Jul 2004
Potsdam, Germany
3·277 Posts 
Thanks for the testing, Zak!
Even with binaries that aren't optimized for the CPU, it is 40% (Step1) to over 60% (Step2) faster than a P4 Prescott  at least for this first test. I wonder how the Core2 performs in relation to an Athlon64. I guess that currently, the A64 will pull away (due to assembly support), but the Core2 could be a real competitioner once the software is optimized. 
20060829, 08:34  #10  
Apr 2003
Berlin, Germany
361_{10} Posts 
Quote:
If the instruction mix is more SSE2, then Core2 will benefit. If it's more based on integer code, then we need to see results for a conclusion. 

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