Mersenne Digest Friday, July 7 2000 Volume 01 : Number 755 ---------------------------------------------------------------------- Date: Wed, 5 Jul 2000 01:58:46 EDT From: [EMAIL PROTECTED] Subject: Mersenne: Re: Mersenne Digest V1 #754 <<unwanted superconductivity>> I have never heard this phrase before. :-P Anyway, silicon won't superconduct, and if the aluminum or copper interconnects did (I think that Cu superconducts, not sure about Al), that wouldn't be too much of a loss, eh? Stephan Lavavej _________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Wed, 5 Jul 2000 00:51:22 -0700 (PDT) From: Francois Gouget <[EMAIL PROTECTED]> Subject: Re: Mersenne: a question regarding setup in dualboot enviroment On Sat, 1 Jul 2000, Dennis [iso-8859-1] J�rgensen wrote: [...] > To submit results etc. I have to connect through a proxy, so I have made > a primenet.ini file, as the readme.txt file (and ips faq) states. It > currently looks as follows: > > [PrimeNet Proxy] > ProxyHost=<removed> > ProxyUser=<removed> > ProxyPass=<removed> > ProxyMask=1 > EntropiaIP=216.120.70.80 > > This works in windows, but in Linux mprime reports "ERROR 2250: Server > unavailable". Maybe you already tried this but could it be a CR/LF problem? - -- Francois Gouget [EMAIL PROTECTED] http://fgouget.free.fr/ Computers are like airconditioners They stop working properly if you open WINDOWS _________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Wed, 5 Jul 2000 11:55:49 -0400 (EDT) From: Douglas Mar <[EMAIL PROTECTED]> Subject: Mersenne: some comments on cooling electronics hi all, first of all, I normally read the digest version, so please take that into account if my comments are mis-timed -- or otherwise seem misguided :) Many of the comments below have already been mentioned by John Pierce, Lucas Wiman, Martijn, and Brian Beesley. In my experience, cooling electronics components and circuitry presents a lot of challenges both for the operation of the components themselves, and for the packaging. It's certainly true that cooling chips often (but not always) makes them perform better--generally the allowable bandwidth goes up and the thermal noise goes down. There are limits, though, to how low one should go. For silicon chips, the main problem (at typical material purity levels) is carrier freezeout somewhere between 120 (deg) Kelvin and 50 K. Below the freezeout temperature, the chips will generally not work at all. It is certainly possible to bias the transistors so that the carriers get heated and refrain from freezing, but then the cooling apparatus (which lowers the temperature of the semiconductor lattice) doesn't "thermalize" the electrons, and therefore isn't completely effective. In some other materials, the transistor action can work all the way down to temperatures where quantum effects become important. Examples are GaAs FETs, which are built for speed and low-noise. If one is careful, condensation and freezing (of water ice) can be handled. I've never had a problem with corrosion (except in components and assemblies that were thermally cycled often). More tricky is the cooldown from room temperature to temperatures to e.g. 77K (Liquid Nitrogen), because the differential contraction between dissimilar materials can break component cases and snap wire bonds. This is true for passive garden variety components (such as the bypass caps) on a board, and is one reason why it's undesirable to spend a lot of resources on cooling electronics that are designed to work at room temperature. regards, Doug Mar [EMAIL PROTECTED] _________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Thu, 06 Jul 2000 00:39:19 PDT From: "Dennis Peter" <[EMAIL PROTECTED]> Subject: Mersenne: Q: GIMPS Multi-threaded Hi there, I have two questions... they may have been answered before. #1: I have a dual processor BP6 motherboard running 2 Intel Celeron 433Mhz processors. I have 2 instances to GIMPS running and everything works OK. When I close ONE of the instances, the other remaining GIMPS instance runs *faster*. Can someone please explain that phenomenon to me? Why would it run faster? It still takes 50% CPU cycle in my task manager. #2: I understand that GIMPS uses the FFT algorithm to do rapid modulo multiplication. Is it possible (or even feasible) to split that atomic FFT task and make it multithreaded to utilize both CPUs in my computer? Would it improve performance? Would it even make sense? Thanks in advance, - -Dennis ________________________________________________________________________ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com _________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Thu, 06 Jul 2000 10:31:50 +0200 From: "Steinar H. Gunderson" <[EMAIL PROTECTED]> Subject: Re: Mersenne: Q: GIMPS Multi-threaded At 00:39 06.07.00 -0700, Dennis Peter wrote: >#1: I have a dual processor BP6 motherboard running 2 Intel Celeron 433Mhz >processors. I have 2 instances to GIMPS running and everything works OK. >When I close ONE of the instances, the other remaining GIMPS instance runs >*faster*. Can someone please explain that phenomenon to me? Why would it >run faster? It still takes 50% CPU cycle in my task manager. Most likely, the problem here is getting fast access to memory. When both CPUs are working as fast as they can, the bottleneck is probably that the memory bus is full (or whatever you call it :-) ). >#2: I understand that GIMPS uses the FFT algorithm to do rapid modulo >multiplication. Is it possible (or even feasible) to split that atomic FFT >task and make it multithreaded to utilize both CPUs in my computer? Would >it improve performance? Would it even make sense? This has been discussed earlier on the list (see the archives for an in-depth discussion), and the conclusion was: Yes, in theory, it's possible, but you'd require extremely fast communication between the CPUs somehow, and it would really be much more trouble than it's worth. It depends a bit on how the L2 cache is -- shared or not. Or perhaps I just remember wrong again, but at least there are people on this list to correct me ;-) /* Steinar */ _________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Thu, 06 Jul 2000 12:00:42 -0700 From: Stefan Struiker <[EMAIL PROTECTED]> Subject: Mersenne: 65-Bit Factors Of The "Factor=" Stripe Zdrastie! Where would I look to find 65-bit factors found during "Factor=" Trial Factoring? I see that P-1 Factoring has turned up some absolute whoppers! Best Wishes, Stefanovic _________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Thu, 06 Jul 2000 12:13:40 -0700 From: Stefan Struiker <[EMAIL PROTECTED]> Subject: Mersenne: ETH Scores A 500-Unit FloorTop, Local Boyz Make Good. PrimeLand? To start a supercomputer company it only takes two brothers - Swiss Dalco delivers 500 processor system to ETH Zuerich - ---------------------------------------------------------------------- The ETH Zuerich has installed a large Linux cluster that will be expanded later this month to 500 processors, 250 Gbyte of memory and 2 Tbyte of data. Because the machine is worth more that 1.5 million Swiss Francs, European regulations require an open tender that has to adhere to strict rules. So who won this tender? One of the big supercomputer companies you would assume. Not so, a small Swiss company Dalco employing 8 people but with a yearly turnover in the 10 million Franc range, solved the legal issues, the technical problems, convinced the ETH they could do the job, and offered the lowest price. Hence the cluster, called Asgard, was installed by the company of Christian and Francois Dallman. The cluster runs Linux, provided by SuSE which has a number of additional tools for running a cluster and supporting parallel programmes. Read more: http://www.hoise.com/primeur/00/articles/corner/AE-PL-06-00-5.html More articles from Ad Emmen: http://www.top500.org/Articles/ Best Wishes, Stefanovic _________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Fri, 07 Jul 2000 01:31:07 -0400 From: Nathan Russell <[EMAIL PROTECTED]> Subject: Re: Mersenne: 65-Bit Factors Of The "Factor=" Stripe Stefan Struiker wrote: > > Zdrastie! > > Where would I look to find 65-bit factors found during "Factor=" Trial > Factoring? I see that P-1 Factoring has turned up some absolute whoppers! > > Best Wishes, > Stefanovic I don't know what to tell you. One of the current weaknesses in PrimeNet is that it does not gather information on the method used to find a factor. However, you might consider writing a little program that would look through the cleared-exponent report to find factors whose k-value is very rough, say with a prime factor >3,000,000 or with multiple ones > 250,000 (these figures, BTW, are over-extimates of the possible extent of 'automatic' P-1.) Nathan _________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Fri, 07 Jul 2000 11:02:21 +0100 From: gordon spence <[EMAIL PROTECTED]> Subject: Mersenne: Cleared Exponents Not Credited to My Account I sent this to the entropia guys a couple of days ago, no reply so I am posting it to the list for comments/any similar experiences etc. >Hi Guys, >Hoping you can clear up a small mystery for me. In the last two weeks days >I have checked in > >4980683 62 D 0x45138F74BD0D0A__ 29-Jun-00 12:17 egonotmgw >4984561 62 D 0xAD6F0F58CD3622__ 04-Jul-00 12:30 egonotmgw >5037433 62 D 0x410DCAFD091E69__ 19-Jun-00 18:14 4401206 >5044499 62 D 0xE0793275A66557__ 02-Jul-00 08:24 4401206 >5045063 62 D 0x6BAC722A2A3D08__ 04-Jul-00 11:37 labrat02 >5080529 62 D 0x55430DFF80F4A1__ 05-Jul-00 11:42 04401205 >5094601 62 D 0xE76D58565F79E3__ 04-Jul-00 11:40 labrat01 > > >but according to my account report (account: nitro pw: ******) the >exponents checked has only increased by 2 from 412 to 414. Additionally I >have run a double check on M5126657 *twice* now, each time P-1 finds a >factor, it is checked in but it is still showing in my exponents under >test list. >BTW they all *do* show in the completed exponents section of my account >report!!!! > >Is there a problem with the check-in scripts? I am concerend for a couple >of reasons > >1. The obvious one, I am not getting time credited. >2. If results are hitting the database correctly we are in for a lot of >trouble later..... > >regards > >Gordon regards G _________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ End of Mersenne Digest V1 #755 ******************************
