P-1 Rankings
 

Hello,

I've been donating computer cycles to GIMPS for a little less than two months now.

In that time, the two PCs that are dedicated to LL (I have two others dedicated to TF and LL-D) have accumulated four P-1 results as a prelude to starting LL work on their numbers.

What puzzles me is that these four (count 'em, 4) results, adding up to a grand total of 11 GHz-days, have already put me at the 58th percentile in the P-1 rankings.

Is there really so little P-1 work being done, that one can jump over half the listed participants with just four results?? At the end of last month I had a mere three results and that had already zoomed me up to the 47th percentile.

What's up with P-1 ?

Rodrigo

[QUOTE=Rodrigo;231107]Is there really so little P-1 work being done, that one can jump over half the listed participants with just four results?? At the end of last month I had a mere three results and that had already zoomed me up to the 47th percentile.[/QUOTE]
Yes. As your experience demonstrates. :smile:
Most of the users listed (on any of the lists, not just P-1) never bothered to do more than two or three assignments, and since they are (mostly) older than your assignments, they were (usually) a bit less work and so a bit less credit per assignment. A good deal of the people even have 0 credit, (as of this writing, all 541 tied at rank 3903, or 541/(3903+541)=~12.2% of the people) so a single result, no matter how small, will put you in at least the 12th percentile. The upper portions of it (80, 90, 99 percentile) are much harder to reach.

[QUOTE=Mini-Geek;231113]The upper portions of it (80, 90, 99 percentile) are much harder to reach.[/QUOTE]

Yes I am closing in on 1,000 P-1s lifetime and 800 for the past year.
This puts me in the 99th Percentile in both; however so would 250 lifetime and 275 for the last year.

But only about 20 results will get you to 90th lifetime and about 10 will get to to 80th on both lists.

On the other hand if you are looking for top 100 or top 10 you will need about 80 and 1,000 respectively for last 365 days standings AND about 650 and 5,000 respectively for the Lifetime standings......MUCH more of a stretch.

[QUOTE=petrw1;231116]On the other hand if you are looking for top 100 or top 10 you will need about 80 and 1,000 respectively for last 365 days standings AND about 650 and 5,000 respectively for the Lifetime standings......MUCH more of a stretch.[/QUOTE]

How much is that in "1976 Toyota Corona years"? :razz: Sorry couldn´t resist.

[QUOTE=ATH;231123]How much is that in "1976 Toyota Corona years"? :razz: Sorry couldn´t resist.[/QUOTE]

Almost exactly: 2^43,112,609-1 :showoff:

[QUOTE=Mini-Geek;231113][...]Most of the users listed (on any of the lists, not just P-1) never bothered to do more than two or three assignments[...][/QUOTE]
Of course it's not always a question of not "bothering" to do more. :smile: Some of us have dabbled with P-1 (or other categories) in the past and then come to the conclusion that our resources are better used for a different work-type from the point of view of the project as a whole. In my case I realised that the memory I was allowing for P-1 factoring was less than most users with the result that I could be missing factors which other contributors would find. So I switched to LL double-checks.

Mini-Geek,

Thanks for the explanation, it makes sense.

Rodrigo

[QUOTE=petrw1;231116]Yes I am closing in on 1,000 P-1s lifetime and 800 for the past year.
This puts me in the 99th Percentile in both; however so would 250 lifetime and 275 for the last year.

But only about 20 results will get you to 90th lifetime and about 10 will get to to 80th on both lists.

On the other hand if you are looking for top 100 or top 10 you will need about 80 and 1,000 respectively for last 365 days standings AND about 650 and 5,000 respectively for the Lifetime standings......MUCH more of a stretch.[/QUOTE]
petrw1,

Thanks for the different angle.

I was going to comment on this to Mini-Geek, but I had to make sure of my calculations first so I ended up leaving my reply to him kind of brief. What he said led me to wonder how many PCs it would take to catch up to "curtisc," the leader in the overall "top producers" rankings.

Fortunately they have a Website, where they report having more than 850 computers participating, yielding 875,000 or so GHz-Days of work in the last year.

Now that my main computers have turned in their first LL results, I have numbers to work with for some back-of-the-envelope comparisons. Both are dual-core Pentiums, one a 2.20 GHz processor and the other a 2.00. Betwen the two of them they're averaging roughly 1.6 GHz-day per core, which would total 584 GHz-Days per year, per core. That's a starting point.

So if I were to go out and buy 160 PCs featuring Intel i7-980 six-core processors :smile:, with each core running at 3.33 GHz (i.e., about 1.57 times faster than my 2.2 and 2.0 GHz machines), I figure I could output about 917 GHz-days per core in a year. Multiplied by six, that's just about 5500 GHz-Days per year for each machine. Times 160, it's 880,000 GHz-Days, and presto! -- I'm in first place next year. :squash: Piece of cake.

Of course there are details to be taken into account and adjustments to be made to the numbers -- and I do recall reading something about memory bandwidth limitations for the 980 -- but I'm just musing over coffee. :coffee: One can dream...

Rodrigo

I think you're underestimating i7-980s.
[url]http://www.mersenne.org/report_benchmarks/?exover=1&exbad=1&specific_cpu=4369094[/url] (benchmarks of i7-980s)
[url]http://mersenne-aries.sili.net/throughput.php?cpu=Intel(R)+Core(TM)+i7+CPU+965+%40+3.20GHz|256|8064&mhz=3600[/url] (the closest thing the site has to an i7-980, with a speed such that the 3072K benchmark runs at the same speed as an i7-980)
An i7-980 at 3.3 GHz can do about 3.6949 Ghz days per day at roughly the FFT size of current first-time LL candidates (3072K). Since that's for 25.11 benchmarks, we can add 10%-25% to that if we use v26 (for my i5, which has a similar architecture, 3072K was 25% faster). So 4.06439 to 4.618625 GHz days per day. That comes to 1484.5 to 1687 GHz days per year per core. Multiplied by six cores, 8907 to 10122 Ghz days per year per CPU. To hit your goal of 880,000 Ghz days per year, you'd need about 99 to 87 CPUs.
One i7-980 is $1000. Let's say you could build each system for $1400 (leaving a bit for decent MB and RAM, but very barebones...actually I don't know if it could be done for that cheap). That means you can plan to spend $121,800 to $138,600 on the computers, plus plenty more time and money on setting up the computers, replacing DOA parts, and paying for the electricity to run and cool this monster farm.
This is, like your calculations, quite back-of-the-envelope, but I think it's a better estimate than yours. :smile: It'd probably be far more cost-effective to use a cheaper CPU, like a quad i5 or i7, but it's still amazing that with around 100 CPUs you might be able to match curtisc!

A few statistics
 

[QUOTE=Rodrigo;231107]What's up with P-1 ?
Rodrigo[/QUOTE]

I'm another relative noob (4 months on Prime95 so far) and noticed the same thing. Having allocated just one core to P-1, I find myself up at the 97th percentile for P-1. That surprised me.

When I dug into it, I noticed that the first time primalty tests get the most GHz-Days, while the trial factoring gets the most results. No great suprises there. Here's the current distribution of assignments, and how many GHz-Days were spent over the last year per category
[CODE]
[FONT=Courier New] TF P-1 LL LL-D (Data retrieved 9-26-10)[/FONT]
[FONT=Courier New]GHz-Days 11% 4% 83% 12%[/FONT]
[FONT=Courier New]Assignments 57% 1% 31% 12%[/FONT]
[/CODE]

Not to my surprise, LL work gets the most cpu time, but trial factoring has the bulk of the assignments.

I like P-1 work because it puts my i7 processor to serious use, and still give me results every day and a half or so. I got so tired of waiting 3 weeks just to see "LL done - not a prime". At least this way I get some timely feedback and the occasional semi-success (factor found).

[QUOTE=Mini-Geek;231513]I think you're underestimating i7-980s.
[/QUOTE]
Mini-Geek,

Wow, your numbers make it look even better than I thought. It IS amazing.

A hundred computers, neatly arranged side by side on a series of shelves. Maybe if I win the Publishers Clearing House sweepstakes...!

To go off on a bit of a tangent -- It sounds like you're happy with Prime95 v26. Would you say that it's ready for "prime" time (so to speak -- sorry, I couldn't resist) ?

Rodrigo