20060820, 19:20  #1 
"Jason Goatcher"
Mar 2005
3·7·167 Posts 
sieving speeds for Intels
I've started a new thread in the hopes of convincing people with Intels that it's worthwhile to sieve. I have a dualcore 2.8GHz PentiumD and I can sieve at about 11.9 kp/s per core, which sounds slow, but I'm knocking down candidates at about 2m30s a candidate, which is significantly faster than even the slowest test.
I would implore people with Intels to consider sieving a small, 5G range, to help the project. I feel it would speed up the overall project, and make the primes per test ratio a lot denser. We'll also probably find the actual primes a lot faster if people would favor sieving over PRPing for a while. Just my opinion. 
20060820, 19:48  #2 
Sep 2002
Database er0rr
10234_{8} Posts 
Interesting. Would a 64bit sieve with a 64bit operating system on one core a 64bit Pentium "D" out perform a sieve running on a 32bit Athlon?
Last fiddled with by paulunderwood on 20060820 at 19:49 
20060820, 20:08  #3 
Jun 2003
2^{2}×397 Posts 
May be some one could set up an exchange, where someone with an athlon would donate time sieving and inexchange you, with a p4, would PRP numbers for him. Credit for all PRP work goes to the athlon owner and factors belong to the P4 owner.
What do you think? 
20060820, 20:21  #4 
"Mark"
Apr 2003
Between here and the
3·17·131 Posts 
I'm tempted to get one of the new Mac Pros (in addition to my G5, not to replace it) so I could find out. Unfortunately, I doubt I could convince my wife to spend the money on one.

20060820, 20:38  #5  
Jun 2003
1010100001011_{2} Posts 
Quote:
Net Burst (P4) is pretty bad in sieving. Core 2 generally rocks  being comparable to Athlon 64s clockforclock (maybe even better). Of course, they're even better at PRP than P4!! 

20060820, 21:34  #6  
"Mark"
Apr 2003
Between here and the
6681_{10} Posts 
Quote:


20060820, 21:51  #7 
Jun 2003
5,387 Posts 
Aah! My bad. Are you looking for instruction timings/latency etc., or just a reference? If it is the latter, AMD64 reference can be obtained from AMD's site.

20060821, 12:38  #8 
"Mark"
Apr 2003
Between here and the
3×17×131 Posts 
Timings and latencies are nice, but the reference is more useful. The NASM manual is a start, but it doesn't have 64bit instructions. Do Intel and AMD use the same 64bit instructions?

20060821, 13:44  #9  
Jun 2003
150B_{16} Posts 
Quote:


20060823, 00:06  #10  
Mar 2003
New Zealand
485_{16} Posts 
Quote:
Finding a single prime eliminates roughly 25,000 candidates at the moment. It would take your P4 something like a month to eliminate this many candidates by sieving. I can only guess, but I think if you spent a solid month PRP testing the smallest candidates you would be unlucky not to find a prime. There are other ways to look at it. 

20060825, 23:05  #11  
"Jason Goatcher"
Mar 2005
3×7×167 Posts 
Quote:
A while back, I used an odds figuring program to calculate the odds of a random number, of the form k*2^n1, being prime, and came up with a simple formula which I felt Riesel Sievers could use to figure out where each computer would best help the project, statistically. Unfortunately, there isn't a base5 version of the program, so I've been forced to guess at what would be best. Btw, the program is called pr_prob, and it's on a yahoo group which has to do with prime numbers. Unfortunately, I forget the precise name of the group. 

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