4096 P4 help wanted
 

I am going to be running a 77.9 M on a fast P4, that has The highest quality PC2700 i could get my hands on(cl2 @190, CL2.5@220) I would like to see some benchmarks of 2.4-2.5 Ghz P4's(to eliminate processor speed as a variable) doing 4096 ffts. Also what ram timings, type of ram,and chipset are you using. Anyone who can help will be well appreciated. I will be posting my timings as I get them tonight. Thanks.

Is it 4096K or 4608K? I ask because for the time I did mine (I gave up after 2 weeks!) I used a 4608K FFT...

from the status page at mersenne.org

[code:1]69100000 79300000 562,700 0 299,584 0 0 263,116 0.35 8,866,276 2.604 4096 [/code:1]

P4 2.329 GHz is 246 milliseconds

PC870 RDRAM


Note: Version 23 will likely speed this up by 7% (or more).

ok, P4 2.46ghz DDR308 cl2

244 ms(average 100 iterations)

Lemme find a keyboard and i will try 4/5 (cpu/ram) and some other CL values.

I should be able to get DDR380, 266, 333, and 400(2 systems)

/edit version 22.8 knocked a ms off the time versus 22.7. That is nearly 22 hours saved.

How to benchmark such high FFT size?

in the advanced menu choose time and enter 77900000 for the exponent size, and a number for the #of iterations(i use 100 as there are many things that can skew a benchmark, the larger sample size helps keep errors too a minimum)

Then take the total time and divide by the number of iterations for an average, or use the best time and post it. I like to use the average, but I am not picky.

And thank you.

~224ms

P4 1.8@ 2520MHz
RD1120

This thing is pretty linear until some 'outside' factor kicks in, such as the cache size limitation. Let t be the table size and s be the time in miliseconds, my XP 1800+ is roughly

s = 0.1t - 4

It gives me ~400 ms for ~4000k table size but my test told me 466. Need another approximation once the 256k cache shows.

For 512k cache, I suspect it is linear till ~4000k. Once we are in the 200 day range, a day or two wont matter as much.

some data...
 

Average time on 1,000 it:
P4 1.6a@2.24 (16X140)=260.483
P4 2.0a@2.3 (20X115)=246.706
P4 2.26b@2.6 (17X153)=223.251
P4 2.0a (20X100)=294.332
P4 1.8a@2.52 (18X140)=234.151
Regards from Italy.
Guido

Re: 4096 P4 help wanted
 

[quote="Tasuke"]I am going to be running a 77.9 M ...quote]
Hi! My faster P4 should take less than 195 days for testing M77,900,000 wich is not much more than 150 days needed by my "old" TBird 0.9 Ghz for a 10mio digits exp. some time ago. So I'd like to test such a monster number as well...
How to ask Primenet for exponents like these? Thanks and regards from Italy.
Guido