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 dual-core 2.8GHz Pentium-D 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.

Interesting. Would a 64-bit sieve with a 64-bit operating system on one core a 64-bit Pentium "D" out perform a sieve running on a 32-bit Athlon? :unsure:

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?

[QUOTE=paulunderwood;85328]Interesting. Would a 64-bit sieve with a 64-bit operating system on one core a 64-bit Pentium "D" out perform a sieve running on a 32-bit Athlon? :unsure:[/QUOTE]

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.

[QUOTE=rogue;85331]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.[/QUOTE]

The apple site shows that Mac Pro uses Intel Xeon "Woodcrest". If so they are based on the Core 2 architecture rather than Net Burst.

Net Burst (P4) is pretty bad in sieving. Core 2 generally rocks -- being comparable to Athlon 64s clock-for-clock (maybe even better). Of course, they're even better at PRP than P4!!

[QUOTE=axn1;85332]The apple site shows that Mac Pro uses Intel Xeon "Woodcrest". If so they are based on the Core 2 architecture rather than Net Burst.

Net Burst (P4) is pretty bad in sieving. Core 2 generally rocks -- being comparable to Athlon 64s clock-for-clock (maybe even better). Of course, they're even better at PRP than P4!![/QUOTE]

I'm more or less interested in the 64-bit capabilities of it. That it can be both great at sieving and PRPing is nice, but I can do PRP tests for other projects (PIES and GFN) on my G5. What I haven't seen yet is a 64-bit Intel ASM manual.

[QUOTE=rogue;85333]I'm more or less interested in the 64-bit capabilities of it. That it can be both great at sieving and PRPing is nice, but I can do PRP tests for other projects (PIES and GFN) on my G5. What I haven't seen yet is a 64-bit Intel ASM manual.[/QUOTE]

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.

[QUOTE=axn1;85334]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.[/QUOTE]

Timings and latencies are nice, but the reference is more useful. The NASM manual is a start, but it doesn't have 64-bit instructions. Do Intel and AMD use the same 64-bit instructions?

[QUOTE=rogue;85357]Timings and latencies are nice, but the reference is more useful. The NASM manual is a start, but it doesn't have 64-bit instructions. Do Intel and AMD use the same 64-bit instructions?[/QUOTE]

More or less. Here are a bunch of [URL="http://en.wikipedia.org/wiki/EM64T#Differences_between_AMD64_and_EM64T"]differences[/URL]

[QUOTE=jasong;85325]I've started a new thread in the hopes of convincing people with Intels that it's worthwhile to sieve. I have a dual-core 2.8GHz Pentium-D 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.[/QUOTE]
So a 1GHz P3 is as fast as a 2.8GHz P4 :-(

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.

[QUOTE=geoff;85418]So a 1GHz P3 is as fast as a 2.8GHz P4 :-(

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.[/QUOTE]
You may be right.

A while back, I used an odds figuring program to calculate the odds of a random number, of the form k*2^n-1, 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 base-5 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. :sad: