Mersenne Digest Friday, June 11 1999 Volume 01 : Number 573
----------------------------------------------------------------------
Date: Fri, 11 Jun 1999 10:47:18 -0500
From: JON STRAYER <[EMAIL PROTECTED]>
Subject: RE: Mersenne: status of exponents
> As I said, unless there is an intervention or someone just
> takes it upon themselves to double-check those exponents
> with software other than George's (the very basis
> of doublechecking), we won't get confirmation of
> M37 until 2003.... <sigh>
So? It's not like we are running out of work.
- --
There are only three reasonable numbers in software engineering:
0, 1 & Infinity
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Date: Thu, 10 Jun 1999 18:23:01 -0500
From: Gary Diehl <[EMAIL PROTECTED]>
Subject: Re: Mersenne: Computer speeds & factoring
Look at www.kryotech.com
Gary Diehl
[EMAIL PROTECTED] wrote:
>
> I have two questions/comments:
>
> Does anyone else remember something from a year or two back (actually may
> still be a modern thing still)? This company was producing very fast
> computers using ordinary chips and making the computer case into a type of
> freezer, encasing the chip and keeping the chip very cold. This made the
> computer run faster, I guess by increasing its conduction, and one result I
> recall is getting a 600 MHz DEC Alpha chip to run at around 767 MHz? Has
> anyone bought this kind of computer, or perhaps done some kind of home
> modification (like all the overclocking)?
>
> My second question, what is a good factoring program for Win98 on a PII
> system that allows you to enter a very large number and attempt to factor it,
> thereby proving it either composite or prime? Thanks for any help.
> ________________________________________________________________
> Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm
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Date: Fri, 11 Jun 1999 13:09:11 -0400
From: Jud McCranie <[EMAIL PROTECTED]>
Subject: RE: Mersenne: status of exponents
At 10:47 AM 6/11/99 -0500, JON STRAYER wrote:
>> As I said, unless there is an intervention or someone just
>> takes it upon themselves to double-check those exponents
>> with software other than George's (the very basis
>> of doublechecking), we won't get confirmation of
>> M37 until 2003.... <sigh>
>
>So? It's not like we are running out of work.
>
But it seems that our work should be better prioritized. There are small
exponents that were assigned at least 17 months ago that haven't been finished.
+----------------------------------------------+
| Jud "program first and think later" McCranie |
+----------------------------------------------+
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Date: Fri, 11 Jun 1999 11:16:15 -0600
From: "Aaron Blosser" <[EMAIL PROTECTED]>
Subject: RE: Mersenne: personal account report
hello members,
> Recently I finished my first exponent testing, hoi hoi hoi, I send the
> result.txt manually to the prime server.
> In my personal report the exponent was registered, so far ok.
> But if I look into my personal report I see that the "LL P90 CPU yrs"
> and all the other numbers on the same line like "Exponents LL tested"
> are still all on zerro, why??
> Did I do something wrong or what.
> Please clear this for me, I like to do it in the correct way.
> best wishes,
Uh oh..! :-)
If I recall, Primenet doesn't count results that are checked in via the
manualtests page; only results sent in automatically will show up.
Is that correct?
Aaron
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Date: Fri, 11 Jun 1999 11:29:27 -0600
From: "Aaron Blosser" <[EMAIL PROTECTED]>
Subject: RE: Mersenne: Computer speeds & factoring
If I'm not mistaken, 2 big problems keep showing up with these
super-coolants.
One is condensation which is really bad bad bad for your motherboard/CPU.
The other (like with Peltier junction coolers) is that they often generate
as much heat as they dissipate. Besides adding an active cooler, you often
need to add even more case fans to get rid of the excess heat the Peltier
devices generates.
There's the nut who is working on total immersion of his system in oil, with
an air-conditioner coil submersed as well. This would solve the problem of
condensate, but there is concern that the mineral oil will break some of the
components on the board.
I like the idea, but instead of mineral oil, some inert water.
Unfortunately, that's not easy to come by :-) otherwise you could just dunk
the whole system into a refrigerated cooler of inert water and ramp up your
clock speeds further than otherwise possible. But for all that effort,
might as well spend more on a faster system.
Aaron
> -----Original Message-----
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED]]On Behalf Of Gary Diehl
> Sent: Thursday, June 10, 1999 5:23 PM
> To: [EMAIL PROTECTED]
> Cc: [EMAIL PROTECTED]
> Subject: Re: Mersenne: Computer speeds & factoring
>
>
> Look at www.kryotech.com
>
> Gary Diehl
>
> [EMAIL PROTECTED] wrote:
> >
> > I have two questions/comments:
> >
> > Does anyone else remember something from a year or two back
> (actually may
> > still be a modern thing still)? This company was producing very fast
> > computers using ordinary chips and making the computer case
> into a type of
> > freezer, encasing the chip and keeping the chip very cold.
> This made the
> > computer run faster, I guess by increasing its conduction, and
> one result I
> > recall is getting a 600 MHz DEC Alpha chip to run at around 767
> MHz? Has
> > anyone bought this kind of computer, or perhaps done some kind of home
> > modification (like all the overclocking)?
> >
> > My second question, what is a good factoring program for Win98 on a PII
> > system that allows you to enter a very large number and attempt
> to factor it,
> > thereby proving it either composite or prime? Thanks for any help.
> > ________________________________________________________________
> > Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm
> ________________________________________________________________
> Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm
>
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Date: Fri, 11 Jun 1999 14:02:58 -0400
From: Jud McCranie <[EMAIL PROTECTED]>
Subject: Re: Mersenne: status of exponents
At 07:53 AM 6/11/99 -0600, Paul Derbyshire wrote:
>Those are probably just whichever 3M-area exponents got assigned to 286s and
>386s :-)
I wonder about that, however. A 286 can't run Prime95, and a 386 would require
a 387, right?
+----------------------------------------------+
| Jud "program first and think later" McCranie |
+----------------------------------------------+
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Date: Fri, 11 Jun 1999 19:43:55 +0100
From: "Brian J. Beesley" <[EMAIL PROTECTED]>
Subject: Re: Mersenne: status of exponents
On 11 Jun 99, at 10:32, Jeff Woods wrote:
> Exponents are only re-assigned if the machine they are assigned to has not
> been heard from AT ALL over the past 60 days. So long as the machine
> checks in and tells PrimeNet that it is still working, it will let them
> take as long as they want to check the exponent.
So? There's plenty of work left for the rest of us 8-)
>
> This was my complaint from a couple days ago -- one client in particular
> has four exponents checked out for double-checking, and is regularly
> checking in -- taking 11 months to check a single exponent. Even though
> those three "untouched" exponents won't even be LOOKED AT by the machine
> for up to three years, the will never expire because the machine checks in
> regularly (at least every 60 days) and reports that it did a few iterations.
Ah. Someone with a 386.
We've had these before, it usually happens (eventually) that the user
gets fed up or the machine gets upgraded, either way the problem
"goes away".
>
> As I said, unless there is an intervention or someone just takes it upon
> themselves to double-check those exponents with software other than
> George's (the very basis of doublechecking), we won't get confirmation of
> M37 until 2003.... <sigh>
Well, they're not a serious problem, yet. When they _do_ become
isolated instances preventing a landmark link confirmation of M(37)
being achieved, then I'm sure someone will devote a few PII-400 CPU
weeks to clearing them up.
BTW note that PrimeNet does accept results for exponents not assigned
to you, though it does mutter and won't credit you for the CPU time.
Regards
Brian Beesley
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Date: Fri, 11 Jun 1999 19:47:28 +0100
From: "Brian J. Beesley" <[EMAIL PROTECTED]>
Subject: Re: Mersenne: status of exponents
>
> I wonder about that, however. A 286 can't run Prime95, and a 386 would require
> a 387, right?
>
... or a 486 SX would require a 387 or 487 coprocessor.
But since 387s cost buttons, the user might actually have one. The
problem is, a 386+387 is still hopelessly slower than a Pentium, even
at the same clock speed.
Don't you think this discussion has gone on long enough yet?
Regards
Brian Beesley
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Date: Fri, 11 Jun 1999 13:59:09 -0500
From: JON STRAYER <[EMAIL PROTECTED]>
Subject: RE: Mersenne: Computer speeds & factoring
> If I'm not mistaken, 2 big problems keep showing up with these
> super-coolants.
>
> One is condensation which is really bad bad bad for your
> motherboard/CPU.
I worked on a system that keeped the temperature just above the dew point.
But I don't know if I could afford to put one of those in my PC box. :-)
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Date: Fri, 11 Jun 1999 12:35:49 -0500
From: [EMAIL PROTECTED] (Mikus Grinbergs)
Subject: Re: Mersenne: status of exponents
Will the Millenium Deities smite all GIMPS participants unless each
and every exponent under 5000000 has been processed by 12/31/99 ?
Assume uncompleted exponents were reserved in good faith. How does
it make the world a better place to have others come along and say:
"I see that splinter in your eye -- *you* have not finished yet !!"?
WHY are these others so concerned about a few exponents not being
finished soon? What possible difference does it make to them?
mikus
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Date: Fri, 11 Jun 1999 15:07:58 -0400
From: Marc Getty <[EMAIL PROTECTED]>
Subject: Mersenne: 286's and 386's running Prime95
> >Those are probably just whichever 3M-area exponents got assigned
> >to 286s and 386s :-)
> I wonder about that, however. A 286 can't run Prime95, and a 386
> would require a 387, right?
First off, a 286 in order to do floating point math needs a math
coprocessor. The model of math coprocessor that goes along with a
80286 is the 80287 not a 387. But, Prime95 only runs on Windows95, and
Windows95 only runs on 386s and higher so there are no 286s out there
running Prime95.
The lowest end 386 is the 80386SX-16 running at a whopping 16 Mhz. 386
SX's have a 32 bit internal bus (making them Intel's first 32 bit
processor) and a 16 bit external bus. The 386DX is 32 bit inside and
out, but most of the 80386DX-16s out there have a major bug in them
that makes their external bus 16 bit just like the 386 SX. The CPUs
that have this bug are from 1985 and have a double sigma mark on them,
this distinguishes them from the working 386's.
So, anything 386 or higher will run Prime95. Lennart Grebelius has a
great benchmark page setup at:
http://www2.tripnet.se/~nlg/mersenne/benchmk.htm
Here he compares everything from a 386SX-16 to a P2-400 MHz (which is
540 times faster at running Prime95).
Personally I will not run Prime95 on anything less then a P5-166, and
I also will not run it on anything that does not have 32 MB or greater
of RAM. Not that Prime95 is a resource hog, far from it, I just don't
think it's worth my time to install it on anything slower then a 166,
and I don't think it is fair to the user of the machine to run a
program that requires 4 to 5 MB or RAM unless at least 32 MB is
present. But far be it from me to judge how you run it, this is just
my opinion.
- -Marc
Marc Getty [EMAIL PROTECTED]
Department of Dental Informatics, Temple University
http://www.temple.edu/dentistry/di/ 215-204-7710
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Date: Fri, 11 Jun 1999 13:10:36 -0600
From: "Aaron Blosser" <[EMAIL PROTECTED]>
Subject: RE: Mersenne: status of exponents
What is the consensus on exponent "poaching"?
If I see a test that will take well over a year, is it wrong of me to just
do it myself with a manual assignment?
What would be the consequences of that? I know that if I test it and turn
it in myself, the next time the slow machine does an update, it will get an
"exponent already tested" message and remove it from the worktodo, and if it
does finish up eventually and turn it in, would it count as a double-check
(or even triple-check if it really takes a year)?
Aaron
> -----Original Message-----
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED]]On Behalf Of Yvan Dutil
> Sent: Friday, June 11, 1999 8:59 AM
> To: [EMAIL PROTECTED]
> Subject: Re: Mersenne: status of exponents
>
>
> At 07:53 AM 6/11/99 MDT, Paul Derbyshire wrote:
> >Jud McCranie <[EMAIL PROTECTED]> wrote:
> >
> >[Mysterious missing Mersenne exponents]
> >
> >> But I thought that the exponents were reassigned if no result was
> >> reported in 2 months. These were assigned much more than 2 months ago.
> >
> >No, they're reassigned if no update is reported in 2 months. The update
> may be
> >a keepalive or an expected completion date or almost anything.
>
> The limit is 60 days after the completion date, and not since the
> last update.
> These ones never call back in since more than a year. Four of them will be
> still
> allocated a year from now.
>
> prime fact current days
> exponent bits iteration run / to go / exp date updated date
> assigned
> -------- -- ---- --------- ----------------- ---------------
> ---------------
> 4465127 60 470.2 313.8 373.8
> 26-Feb-98 09:23
> 4671439 * 60 369.8 149.2 209.2
> 06-Jun-98 20:31
> 4787599 61 373.9 664.1 724.1
> 02-Jun-98 16:42
> 4833901 61 401.9 407.1 467.1
> 05-May-98 16:35
> 4864591 61 373.0 34.0 94.0
> 03-Jun-98 13:18
> 4876111 61 411.3 51.7 111.7
> 26-Apr-98 07:59
> 4926563 61 436.6 105.4 165.4
> 31-Mar-98 23:58
> 5016679 61 385.5 383.5 443.5
> 22-May-98 02:09
> 5123693 61 369.6 -43.6 16.4
> 06-Jun-98 23:55
>
> Yvan Dutil
>
> ________________________________________________________________
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Date: Fri, 11 Jun 1999 13:56:38 -0600
From: "Blosser, Jeremy" <[EMAIL PROTECTED]>
Subject: RE: Mersenne: Pentium Pro Optimization Help Needed
Or it could be a combination of decoding/code alignment problems
(sub-optimal decode cycles) which cause goofy patterns in loops and such. I
suggest running it thru VTUNE and see what comes up there...
There's the good doc at: http://www.agner.org/assem/pentopt.htm which
explains all this stuff better than I could ever hope to.
- -----Original Message-----
From: Blosser, Jeremy [mailto:[EMAIL PROTECTED]]
Sent: Friday, June 11, 1999 10:06 AM
To: '[EMAIL PROTECTED]'
Subject: RE: Mersenne: Pentium Pro Optimization Help Needed
Umm... decoding optimization (4-1-1 rule)
For example in four_complex_cpm_fft_3:
;;1-1-1
fld R6 ;; I2,I3,A2,r/i,A4,I1,R3,R1
fmul st(3), st ;; B2 = I2 * r/i
;23-27
fsubp st(2), st ;; A2 = A2 - I2
;24-26
;;1 (D1, D2 stall)
fld R8 ;; I4,I3,A2,B2,A4,I1,R3,R1
;;2-1 (D2 stall)
fmul QWORD PTR [edi+24] ;; B4 = I4 * r/i
;25-29
fxch st(4) ;; A4,I3,A2,B2,B4,I1,R3,R1
;;2-1 (D2 stall)
fsub R8 ;; A4 = A4 - I4
;26-28
fxch st(2) ;; A2,I3,A4,B2,B4,I1,R3,R1
Plus all the stores are decoded in separate cycles (2 uOps)
I'm sure someone else will correct my mistakes ;)
I'm sure you checked cache alignments... I can't think of anything else
offhand...
Also, I noticed that no attention was paid to as far as K6 optimization (ie
tossing the fxch's) in the current code... Any effort to improve that or is
it not worth it?
- -----Original Message-----
From: George Woltman [mailto:[EMAIL PROTECTED]]
Sent: Wednesday, June 09, 1999 10:19 PM
To: [EMAIL PROTECTED]
Subject: Mersenne: Pentium Pro Optimization Help Needed
Hi all,
I'm trying to optimize prime95 for the Pentium Pro/PII/PIII
architecture. I'm fairly well versed in various execution units
and latencies, but some mysteries remain.
Are there any experts in this field - maybe even some Intel
employees - that could improve the code further? Even one clock
cycle in a macro that will be executed a few quintillion times is
a big help.
The new assemply macros are at ftp://entropia.com/gimps/lucas1p.mac
for you to look at.
Questions: Why is the code faster when I throw in some
no-ops (actually fxch st(0) instructions)? How can I force the
CPU to execute the floating point micro-ops in the optimal order?
Does reordering the fstp instructions have any effect? Are there
other issues I sould consider?
Regards
George - who is looking forward to IA-64 where I am in control of
the opcode scheduling once again. Not to mention lots of registers!
P.S. The clock timings were measured using the following loop. I can
provide more details upon request.
mov al, 0
mov ecx, 250 ; 1000 iterations
clp1: disp four_complex_cpm_fft_3 8, 16, 32 ;;; or some other
macro
lea esi, [esi+64]
add al, 256/4
jnc clp1
lea esi, [esi-256]
dec ecx ; Check loop counter
jnz clp1 ; Loop if necessary
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Date: Fri, 11 Jun 1999 20:35:07 +0200
From: "Steinar H. Gunderson" <[EMAIL PROTECTED]>
Subject: Mersenne: Re: Mersenne Digest V1 #572
On Fri, Jun 11, 1999 at 08:46:53AM -0700, Mersenne Digest wrote:
>This made the
>computer run faster, I guess by increasing its conduction, and one result I
>recall is getting a 600 MHz DEC Alpha chip to run at around 767 MHz? Has
>anyone bought this kind of computer, or perhaps done some kind of home
>modification (like all the overclocking)?
I saw an article on Slashdot (http://slashdot.org -- try to pronounce that)
some weeks ago. Try to make a search. Whoever wrote that article had made
a dual-CPU cooler, so he could actually _double_ the CPU speed and still
make it run. (It even had some info on _why_ cooling helped.)
>My second question, what is a good factoring program for Win98 on a PII
>system that allows you to enter a very large number and attempt to factor it,
>thereby proving it either composite or prime? Thanks for any help.
As somebody pointed out, the giantint package does exactly that (well,
actually, the numbers aren't 100% sure to be prime) for Linux/UNIX. Either
find someone who's willing to port it, or get Linux.
Example (previously shown on this list):
- ---
steinar:~# echo 123123123123123123123123123123 | ./factor
Sieving...
3 * 7 * 11 * 13 * 31 * 41 * 41 * 211 * 241 * 271 * 2161 * 9091 * 2906161
steinar:~# echo 1231231231231231231231231231231231 | time ./factor
Sieving...
Commencing Pollard rho...
...
111871
*
Commencing Pollard (p-1)...
..................................................................
Commencing ECM...
Choosing curve 1, with s = 346492192, B = 1000, C = 50000:
..
Commencing second stage, curve 1...
....
Choosing curve 2, with s = 2131939374, B = 1000, C = 50000:
..
Commencing second stage, curve 2...
....
18102915799
* 607957991560696039
1.92user 0.00system 0:02.12elapsed 90%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (100major+30minor)pagefaults 0swaps
- ---
- ---snip---
>You must be thinking of KryoTech: http://www.kryotech.com/
Of course, Kryotech too. The article I was referring to showed a way to get
an extra -10 or -20 degrees Celsius `on top of' Kryotech. (Totally built
from scratch.)
- ---snip---
>The optimization guide is packed full of tips. It's about 150 pages
>in total, although half of it is a reference guide.
I've pointed George to this some time ago, and he told me there was a
lot of errors in it. If you look in the source code, all three of these
(usage of CMOVs/branch optimization, avoiding partial register stalls,
and data alignment) are implemented in the code already. However, it
tells very little about FPU optimization on the P6-family, which, I
believe, is what George is after.
Perhaps a posting on comp.lang.x86.asm (if I remember right) would be
an idea? I posted a question there once, and got very much constructive
information back.
>Thanks to David Willmore (not a turkey by any means), I've had a chance to try a soon-
>to-be-released update of my Mersenne code on a 500MHz Alpha 21264s, and it's extremely
>impressive - 0.18 seconds per iteration at FFT length 384K, fully three times faster
>than on my 400MHz 21164.
Hmmm... I'm currently doing an exponent of 7398xxx on my PII/448
(bus-overclocked), which should be 384K FFT length. My best result is 0.197
secs/iteration (stable, but not across reboots) using mprime 18.1. This
means the PII is about as fast as an Alpha (a little slower) on the same
clock speeds. Is Alpha over-hyped, is something wrong, or is just George
a terriffic x86 assembly coder?
>The performance on the 21264 is in line with the MIPS
Which means Intel is also in line with the MIPS? (I just saw some benchmarks
that promised K7 to be 40% faster than PII at FPU, looks like we have good
times ahead of us!)
- ---snip---
>1. Why have 2nd LL tests been done in many cases when there are still
>exponents whose status is unknown?
Probably because P133s (is this number right) or slower are now automatically
assigned double-checking results, instead of full LL tests.
(As a side note, an AMD K6/200 instantly began checking out double-checking
assignments instead of factoring assignments when I set it to work 24 hours
(instead of 8) a day. I consider this a bug, unless somebody has a good
reason K6s shouldn't do integer arithmetics instead of FPU work.)
- ---snip---
>My vote for "Most Inane" would be to the guy a year or two ago who claimed
>to know for an absolute certainty that there were only, (I think it was) 37
>Mersenne primes. Whatever the number was, it was about one more than had
>been discovered at that point.
`It is a scientific fact that your vision becomes worse if you shave off your
beard.' (Or whatever whoever said.)
I think much stupid has been said. Never say anything and claim 100%
certainity :-)
- ---snip---
>Even with a nice 550MHz PIII, a 33M exponent could be tested in maybe around
>1/12 the time of a P90 (about 6 times faster, as well as being much more
>optimized...maybe more like 1/10). I think 80 years is a bit of an
>overestimate though...but I could be wrong on that.
In fact, I think the 90 GHz number _was_ right. (There was a post on this
list, where poster showed that even with a CPU that fast, it would take
ages to check a single billion-digit Mersenne prime.)
- ---snip---
> So we are about 7.5*10^10 P90 years away from our first billion digit prime.
Hmmm, that depends a bit on where it is, and if it is there at all!
- ---snip---
> Following conservative estimates of cpu power and number of participants
>doubling every two years, I'd guess that we will have a our first billion
>digit prime in 2021, when we have 40 million participants and Pentium XV
>1000GHz processors.
I can remember seeing some figures predicting the number of Internet users
would cross the world population in just 20 years or so.
About all this lifetime stuff, I'm having a greater chance than most of
you, BTW. So there :-)
- ---snip---
>Talking about impatience, there is something I don't understand:
>are we waiting just for the doublecheck to be completed or does the
>EFF prize somehow require that M38 be kept secret until publication?
>I hope not, that would be very strange indeed...
Both, I think. It's not very strange, I guess they want it done `the
right way'. You know, that's how `grown-ups' think, and it's their
money, so they decide.
- ---snip---
>Some exponents take much longer than 2 months to LL test on slower machines.
>Those are probably just whichever 3M-area exponents got assigned to 286s and
>386s :-)
Well, most certainly 386s or 486s, my PII can run a 3M-exponent in a day
or so. (286s can't run Prime95, of course, they would need a special version,
and I'm not sure if George is keen on making one.)
- ---snip---
>As I said, unless there is an intervention or someone just takes it upon
>themselves to double-check those exponents with software other than
>George's (the very basis of doublechecking), we won't get confirmation of
>M37 until 2003.... <sigh>
That depends on what you mean by `confirmation'. Since I'm totally lost
in the number of Mersenne primes being found, I guess M38 is the unconfirmed,
million-digit one, and M37 is the previous one. So, I guess what you're
looking for, is confirmation that M37 really is the 37th Mersenne prime,
not that it is prime. Is it really that important?
- ---snip--
>But if I look into my personal report I see that the "LL P90 CPU yrs"
>and all the other numbers on the same line like "Exponents LL tested"
>are still all on zerro, why??
>Did I do something wrong or what.
>Please clear this for me, I like to do it in the correct way.
`The correct way' is reporting automatically, via Prime95/mprime/whatever.
I did the same error, and Scott pointed me to the FAQ page... If you
re-report, using the automatic method, you will be credited. If this
is impossible, ask Scott ([EMAIL PROTECTED]), and I guess he'll
find a solution for you.
Oh, you could always send the results to me, so I can get the credit :-)
>Plus all the stores are decoded in separate cycles (2 uOps)
>I'm sure someone else will correct my mistakes ;)
Since the code is called (approx.) 500,000 times _per iteration_, and the
FPU unit has latency of at least 2-3 cycles per instruction (correct me),
I guess decoding stalls is only minor here, even though the function is
inlined, so it has to be decoded many times.
>Also, I noticed that no attention was paid to as far as K6 optimization (ie
>tossing the fxch's) in the current code... Any effort to improve that or is
>it not worth it?
I made an optimization of George's code, without more that a few FXCHs, but
it's probably not working, since I never had access to MASM... If you're brave,
you could always have a look at it (mail me) and try to fix it.
/* Steinar */
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Date: Fri, 11 Jun 1999 16:11:21 -0400
From: Jud McCranie <[EMAIL PROTECTED]>
Subject: RE: Mersenne: status of exponents
At 01:10 PM 6/11/99 -0600, Aaron Blosser wrote:
>
>If I see a test that will take well over a year, is it wrong of me to just
>do it myself with a manual assignment?
I think that is what should be done. A double check will have to be done
anyway, so let the year-long test serve as the double check. Anything less
than a P=166 is defaulting to double check assignments. If it is taking a
year, then it is running on something considerably slower.
+----------------------------------------------+
| Jud "program first and think later" McCranie |
+----------------------------------------------+
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Date: Fri, 11 Jun 1999 16:33:49 -0400
From: Jeff Woods <[EMAIL PROTECTED]>
Subject: Re: Mersenne: status of exponents
>WHY are these others so concerned about a few exponents not being
>finished soon? What possible difference does it make to them?
It doesn't affect me personally in the slightest, other than wanting to see
that line item on the GIMPS home page under "Milestones", that we know M37
is truly M37 and not M38. Part of the reason many of us do this is to see
the progress in material ways like that, and I don't want to have to wait
until 2003 to see that milestone reached, when it is one computer holding
up the chase. That's not the case today (one holdout stopping us) but it
won't be too long before it is...
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Date: Fri, 11 Jun 1999 15:56:27 -0500
From: Gary Diehl <[EMAIL PROTECTED]>
Subject: Re: Mersenne: Computer speeds & factoring
Kryotech's FAQ reads:
Q3: How do you prevent ice or condensation from forming around the very
cold CPU?
A3: We have a set of patents and extensive know-how for preventing
condensation. This is the center of KryoTech's expertise arguably our
most important value-add. We have been running -40C
computer systems since December 1994 without condensation!
I also remember reading an early press release on Kryotech a year or so
ago that mentioned they surround the top of the CPU with a specially
insulated cover that prevents the cold (which reaches the CPU top-cover)
from being exposed to the outside air, thereby preventing condensation.
Gary Diehl
Aaron Blosser wrote:
>
> If I'm not mistaken, 2 big problems keep showing up with these
> super-coolants.
>
> One is condensation which is really bad bad bad for your motherboard/CPU.
>
> The other (like with Peltier junction coolers) is that they often generate
> as much heat as they dissipate. Besides adding an active cooler, you often
> need to add even more case fans to get rid of the excess heat the Peltier
> devices generates.
>
> There's the nut who is working on total immersion of his system in oil, with
> an air-conditioner coil submersed as well. This would solve the problem of
> condensate, but there is concern that the mineral oil will break some of the
> components on the board.
>
> I like the idea, but instead of mineral oil, some inert water.
> Unfortunately, that's not easy to come by :-) otherwise you could just dunk
> the whole system into a refrigerated cooler of inert water and ramp up your
> clock speeds further than otherwise possible. But for all that effort,
> might as well spend more on a faster system.
>
> Aaron
>
> > -----Original Message-----
> > From: [EMAIL PROTECTED]
> > [mailto:[EMAIL PROTECTED]]On Behalf Of Gary Diehl
> > Sent: Thursday, June 10, 1999 5:23 PM
> > To: [EMAIL PROTECTED]
> > Cc: [EMAIL PROTECTED]
> > Subject: Re: Mersenne: Computer speeds & factoring
> >
> >
> > Look at www.kryotech.com
> >
> > Gary Diehl
> >
> > [EMAIL PROTECTED] wrote:
> > >
> > > I have two questions/comments:
> > >
> > > Does anyone else remember something from a year or two back
> > (actually may
> > > still be a modern thing still)? This company was producing very fast
> > > computers using ordinary chips and making the computer case
> > into a type of
> > > freezer, encasing the chip and keeping the chip very cold.
> > This made the
> > > computer run faster, I guess by increasing its conduction, and
> > one result I
> > > recall is getting a 600 MHz DEC Alpha chip to run at around 767
> > MHz? Has
> > > anyone bought this kind of computer, or perhaps done some kind of home
> > > modification (like all the overclocking)?
> > >
> > > My second question, what is a good factoring program for Win98 on a PII
> > > system that allows you to enter a very large number and attempt
> > to factor it,
> > > thereby proving it either composite or prime? Thanks for any help.
> > > ________________________________________________________________
> > > Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm
> > ________________________________________________________________
> > Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm
> >
>
> ________________________________________________________________
> Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm
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Date: Fri, 11 Jun 1999 15:17:59 -0600
From: "Aaron Blosser" <[EMAIL PROTECTED]>
Subject: RE: Mersenne: status of exponents
Okay then...like it or not, I took all those exponents that were posted to
the list earlier and started them up.
I had 3 quad-processor and 1 dual-processor PPro 200 machines not doing
anything, so they're now working on those exponents.
Aaron
> -----Original Message-----
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED]]On Behalf Of Jud
> McCranie
> Sent: Friday, June 11, 1999 2:11 PM
> To: Aaron Blosser
> Cc: Mersenne@Base. Com
> Subject: RE: Mersenne: status of exponents
>
>
> At 01:10 PM 6/11/99 -0600, Aaron Blosser wrote:
> >
> >If I see a test that will take well over a year, is it wrong of
> me to just
> >do it myself with a manual assignment?
>
> I think that is what should be done. A double check will have to be done
> anyway, so let the year-long test serve as the double check.
> Anything less
> than a P=166 is defaulting to double check assignments. If it is taking a
> year, then it is running on something considerably slower.
>
>
>
> +----------------------------------------------+
> | Jud "program first and think later" McCranie |
> +----------------------------------------------+
>
>
> ________________________________________________________________
> Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm
>
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Date: Fri, 11 Jun 1999 16:55:19 -0500
From: "Richard B. Woods" <[EMAIL PROTECTED]>
Subject: Mersenne: Turkey season, already??? (Was: Whither goest thou, Alpha?)
Ernst W. Mayer wrote:
> I seem to recall a long-buried thread on this list about how long
> various processors take to cook a Turkey
The thread was about a (ahem) modest proposal for updating the standard
unit of GIMPS effort from the current CPU-model-dependent "P90-year" to
a unit that would be independent of CPU models and thus not subject to
obsolescence by advances in chip manufacture. Inspired by the
information-theoretic idea of measuring information in terms of entropy,
whose units are of energy, I propose that we use the energy used to
raise a standard mass (10-kg turkey) to a standard temperature
("done" according to _The Joy of Cooking_) by a GHz-class CPU
adapted for use of its waste radiation in a microwave oven.
>...(screams of "Nooo! Not that again!" in the background :)
Of course not. It's much too early for turkey season, silly!
Richard ("Not a turkey either, but I know one when I see one") Woods
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Date: Fri, 11 Jun 1999 23:09:02 +0100
From: "Brian J. Beesley" <[EMAIL PROTECTED]>
Subject: Re: Mersenne: Re: Mersenne Digest V1 #572
> >My second question, what is a good factoring program for Win98 on a PII
> >system that allows you to enter a very large number and attempt to factor it,
> >thereby proving it either composite or prime? Thanks for any help.
>
> As somebody pointed out, the giantint package does exactly that (well,
> actually, the numbers aren't 100% sure to be prime) for Linux/UNIX. Either
> find someone who's willing to port it, or get Linux.
Microsoft Visual C++ compiles it quite happily under Windoze. Or it
is possible to get gcc to work in a "DOS box".
> Hmmm... I'm currently doing an exponent of 7398xxx on my PII/448
> (bus-overclocked), which should be 384K FFT length. My best result is 0.197
> secs/iteration (stable, but not across reboots) using mprime 18.1. This
> means the PII is about as fast as an Alpha (a little slower) on the same
> clock speeds. Is Alpha over-hyped, is something wrong, or is just George
> a terriffic x86 assembly coder?
I have an Alpha 21164-533. For C code compiled using gcc & run under
linux, it's _at least_ 4x as fast as a PII-350. Considerably quicker
than that, if the code can use 64-bit integers intelligently.
George _is_ a teriffic x86 assembly coder. Ernst Mayer's program is
written in a high-level language (Fortran-90); if anyone has the time
& the skill to do an Alpha assembly optimization of Ernst's code
which is half as good as George's work on Intel, it would almost
certainly run at least twice as fast.
>
> >The performance on the 21264 is in line with the MIPS
>
> Which means Intel is also in line with the MIPS? (I just saw some benchmarks
> that promised K7 to be 40% faster than PII at FPU, looks like we have good
> times ahead of us!)
>
Actually the K7 has pinched some ideas (like the 200 MHz 128-bit data
bus) developed for the Alpha.
I think Ernst was comparing the performance of the Alpha 21264 with
the MIPS R12000 CPU running code from the same (Fortran-90) source.
> (As a side note, an AMD K6/200 instantly began checking out double-checking
> assignments instead of factoring assignments when I set it to work 24 hours
> (instead of 8) a day. I consider this a bug, unless somebody has a good
> reason K6s shouldn't do integer arithmetics instead of FPU work.)
No. The effective CPU speed of a K6 at 200 MHz is _100_ MHz, the K6
FPU is less efficient than the Pentium FPU. Divide that figure by 3
if you're running 8 hrs/day and you end up with less than 50 MHz, so
you get factoring assignments by default. Tell it you're running 24
hrs/day and you will get double-checking assignments.
> Well, most certainly 386s or 486s, my PII can run a 3M-exponent in a day
> or so. (286s can't run Prime95, of course, they would need a special version,
> and I'm not sure if George is keen on making one.)
Waste of time. All the remaining operating 286's in the world put
together probably don't amount to more than a dozen or so P90s.
>
> That depends on what you mean by `confirmation'. Since I'm totally lost
> in the number of Mersenne primes being found, I guess M38 is the unconfirmed,
> million-digit one, and M37 is the previous one. So, I guess what you're
> looking for, is confirmation that M37 really is the 37th Mersenne prime,
> not that it is prime. Is it really that important?
>
It is, if you're going to denote them that way. If you're going to
give them serial numbers in terms of discovery date rather than in
terms of size, we're going to mightily confuse the inhabitants of the
planet Zog when they get our list. In any case, the precedent has
already been set.
We can talk unambiguously about "the 37th Mersenne prime to be
discovered" meaning "Clarkson's Number" or 2^3021377-1, but we should
not talk about the "37th Mersenne prime" (unqualified) until we have
double-checked all the exponents up to 3021377.
I personally find it hard to think in terms of a 38th Mersenne prime
discovery until it's verified. I know it's most unlikely (to put it
mildly) that a "false positive result" would arise by chance, but, as
they say, "If it looks like a duck and sounds like a duck, it
probably _is_ a duck. But I won't be sure until I see it has webbed
feet!"
Sorry for being pedantic.
> Since the code is called (approx.) 500,000 times _per iteration_, and the
> FPU unit has latency of at least 2-3 cycles per instruction (correct me),
> I guess decoding stalls is only minor here, even though the function is
> inlined, so it has to be decoded many times.
Latency is the time between the instruction entering the pipeline and
the operation being complete. However the throughput is 1 floating-
point add or multiply per cycle, so long as the code can keep the
pipeline filled.
If the processor stalls, the execution units empty and you _do_ lose
(at least) the latency period before you start to get results out
again. This is why avoiding stalls is important.
Regards
Brian Beesley
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End of Mersenne Digest V1 #573
******************************
