20070115, 13:13  #89 
Jul 2005
386_{10} Posts 
Just a note to say that I've finally had time to look at proth_sieve on PPC linux. Sheep has given me an account on a suitable machine and I'm trying to fix some strange issues at the moment (almost certainly due to the minor differences in the assembly styles).
The result should be a proth_sieve build for PPCLinux (to go along with the one I have for PPCOSX. Big thanks to Rogue for his work on the very fast mulmod and expmod assembly!) As for the Wii, is Broadway 32bit or 64bit? BTW, My PPC builds of proth_sieve are dreadful for Riesel sieving. They are very good for Sierpinksi (SoB and PSP) but haven't been optimised at all for Riesel (and so they are much slower). 
20070205, 02:20  #90 
Mar 2003
New Zealand
13·89 Posts 
sr2sieve 1.4.19 lifts the sieve limit to 2^63 for the ppc64, it was incorrectly set at 2^52 in previous versions.

20070205, 18:37  #91  
Oct 2006
On a Suzuki Boulevard C90
2·3·41 Posts 
Quote:
Since I'm really not particularly bright, can you tell me if this would impact any work that I've already done? The highest PSP combined sieving that I've done is to 448,300. In Riesel, I've gone to 1,001,600. Thanks, 

20070205, 20:48  #92  
"Mark"
Apr 2003
Between here and the
6592_{10} Posts 
Quote:
BTW, the reason for 2^52 was because that is a limit in the FPU. As the PPC version doesn't using the FPU, the limit is actually 2^63 (one bit less than the number of bits in a register). 

20070207, 01:18  #93  
"Jason Goatcher"
Mar 2005
3×7×167 Posts 
Quote:
2^52 is 4.5*10^15, while 2^63(which is 2048 times bigger) is 9.22*10^18. To get a grasp of how big these numbers are, 2^52 seconds is a little under 143 million years. 2^63 seconds is about 292 billion years. Not that we're counting seconds with these numbers. 

20070207, 01:44  #94  
Mar 2003
New Zealand
13×89 Posts 
Quote:
I was under the impression that SoB had sieved up to p=2^52 for some range of n, but I suppose they stopped when they combined sieves with PSP. In principle it should work right up to p=2^63, but a lot of memory will be required and it probably won't be efficient at that depth. It should still be practical to use up to 2^54 at least. The low factor density makes it a bit difficult to do much testing though. 

20070207, 04:04  #95  
Oct 2006
On a Suzuki Boulevard C90
2·3·41 Posts 
Quote:
Quote:
I just wanted to confirm whether or not I needed to resieve any of the ranges. It looks like the answer is no. Thanks, 

20070215, 11:42  #96 
Jul 2005
2×193 Posts 
Sheep, back looking at this again after a bit of a busy time...

20070215, 12:59  #97 
Jul 2005
2×193 Posts 
OK, sent you a couple of emails. I've found the coredump problem in the lower ranges and so it's all good to go.
To compare sieving speeds of proth_sieve (for PPC 970 and Linux) I did a small range around p = 270005G: Sheep's 2.0GHz PPC 970 G5: Sieving 273005640000000 <= p <= 273024210000000, 900 <= n <= 50000000 273005642053939  10223*2^30572969+1 (xmod 1867044)) 273005643639493  24737*2^49346863+1 (xmod 648), duplicate) p = 273005650000003 @ 571kp/s p = 273005660000023 @ 572kp/s ... 
20070215, 20:36  #98 
Oct 2006
On a Suzuki Boulevard C90
2·3·41 Posts 
I haven't done thorough testing yet, but on a 2.2 GHz 970FX, on adjacent ranges with SoB.dat, sr2sieve (running on 206000206036) is reporting "343582 p/sec" while proth_sieve (running on 206036206072) is reporting "612kp/s". Are the two numbers directly comparable? Is 1 kp equal to 1000 p or 1024 p?
Results with riesel.dat are vastly different. On a 2.5 GHz 970MP, proth_sieve reports 53kp/s while sr2sieve reports ~243000 p/sec on the range 10475901047664. Last fiddled with by BlisteringSheep on 20070215 at 20:39 Reason: added riesel.dat numbers 
20070216, 09:28  #99 
Jul 2005
2×193 Posts 
Yes. 1 kp= 1000 p/s.
So 612kp/sec could be anything from 612000 p/sec to 612999 p/sec. If you want it to report p/sec then remove the multiple of 0.001 on line 770 in proth_sieve.c and change the two "kp/s" on lines 2360 and 2361 to "p/s". Then run ./build And the program is not optimised for Riesel at all. I wanted Sierpinski sieving to be as fast as possible. Sorting it out properly for Riesel is on my big list of stuff to do. 
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