Mersenne Digest Sunday, October 14 2001 Volume 01 : Number 892 ---------------------------------------------------------------------- Date: Fri, 12 Oct 2001 12:24:50 -0400 From: George Woltman Subject: Re: Mersenne: Assigned numbers that were already done Hello all, At 11:20 AM 10/12/2001 -0400, Thern, Royal E wrote: >I recently received an exponent, ostensibly for first-time LL testing, that >seemed rather low (in the 11,000,000's). I looked at cleared.txt, and this >had indeed been already done. Is something going on? Yes. Last week I made available hundreds of exponents that had previously been tested. These LL tests had errors detected during the first run. History has shown that in roughly half of these cases, the final LL test result is incorrect (prime95's error checking cannot catch all errors). My goal is to get at least one clean run on each exponent as we march higher. At worst we get an early double-check, at best we find a new Mersenne prime without waiting 2 years for double-checking to get this high. Have fun, George _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Sun, 14 Oct 2001 07:30:24 +0200 From: "Jean-Yves Canart" Subject: Mersenne: AthlonXP Hello All According to latest benchmarks (http://www.mersenne.org/bench.htm), AthlonXP seems to be slower than the Thunderbird. Does anybody have a technical explanation ? Do we have to consider now Intel/P4 as the best platform (at least for prime95)? Regards, Jean-Yves _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Sun, 14 Oct 2001 03:49:42 -0400 From: Michael Vang Subject: Re: Mersenne: AthlonXP That the P4 is the best platform is a given... I'm curious how the 850 chipset version (RDRAM) compares to the 845 chipset version (SDRAM)... I noticed that Newegg has retail boxed P4s (1.3GHz) with 2x64MB RDRAM for $120... I don't know if it is PC600 or PC800 RDRAM, though... It looks like it would be possible to build a headless P4 box very cheaply, especially if you booted off of a network and didn't have to install a hard disk... On another tangent, I've been meaning to post the shell script that generates the signature at the bottom... It is not a pretty script, but it works... I'm kinda new at this: #!/bin/sh /opt/sfw/bin/wget -O - -q http://mersenne.org/ips/top101to500.shtml | grep Team_Prime_Rib | awk '{printf ("Xyzzy [%3d/%2.3f/", $1, $4)}' /opt/sfw/bin/wget -O - -q http://mersenne.org/primenet/ftop101to500.txt | grep Team_Prime_Rib | awk '{printf ("%3d/%1.3f] http://www.teamprimerib.com/\n", $1, $5)}' Actually, this is version 2 of the script while the one at the bottom is version 3... Version 3 is still so ugly I'd be embarassed to post it... The only difference is it gives the P90 hours per day in addition to the other data... The format is: UserID [LL Rank/LL P90 Years/Factoring Rank/Factoring P90 Years] URL Obviously, you need to modify the script to personalise it... You need to put your UserID in the grep portion, you need to match the filenames that wget pulls to the range you are in and you might need to modify the formatted output depending on what numbers are returned... Also, the path to wget might need to be altered (assuming it is installed!)... There is probably an easier way, but I haven't found it yet... I'd be curious to see if it runs under Windows... I know wget is available for windows and I bet awk is too... Xyzzy [156/76.273/247/3.577/507.98] http://www.teamprimerib.com/ Jean-Yves Canart wrote: > > Hello All > > According to latest benchmarks (http://www.mersenne.org/bench.htm), > AthlonXP seems to be slower than the Thunderbird. Does anybody have a > technical explanation ? > > Do we have to consider now Intel/P4 as the best platform (at least for > prime95)? > > Regards, Jean-Yves > > _________________________________________________________________________ > Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm > Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Sun, 14 Oct 2001 09:17:10 -0000 From: bjb@bbhvig.uklinux.net Subject: Mersenne: Minor milestone Hi, In case any one hasn't noticed: Everyone in the PrimeNet Top 100 Producers list has now contributed more than 100 P90 CPU years. Regards Brian Beesley _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Sun, 14 Oct 2001 11:41:03 -0000 From: bjb@bbhvig.uklinux.net Subject: Re: Mersenne: AthlonXP On 14 Oct 2001, at 7:30, Jean-Yves Canart wrote: > According to latest benchmarks (http://www.mersenne.org/bench.htm), > AthlonXP seems to be slower than the Thunderbird. Does anybody have a > technical explanation ? The Athlon XP lies about its speed. Remember the old Cyrix trick? Well AMD have gone for the same - pick a benchmark that suits you, then claim your chip is "1800+" if it runs _that_ benchmark a wee bit faster than the opposition's chip running at 1800 MHz. I think an Athlon XP 1800+ is in fact running at 1533 MHz. IMHO this is as bad a marketing scam as attatching the XP label, which is obviously designed to hoodwink consumers into thinking that an upgrade is neccessary if the want to run Windows XP - thus enabling AMD to benefit from Microsoft's imminent marketing blitz. The unfortunate thing about this is that I'm afraid that most consumers will swallow at least part of the lies :( Having said all that, AFAIK the basic core of the Athlon XP is much the same as the Thunderbird: it is fabbed at 0.13 microns instead of 0.18 microns, which means keeping it cool should be a bit easier. This should not affect the basic chip efficiency one way or the other. Running Prime95, I would expect an Athlon XP running at 1.4 GHz to be exactly the same speed as a Thunderbird 1.4GHz (266 MHz FSB) in the same board. N.B. you may need a BIOS upgrade to support the Athlon XP due to the changed core voltage. There is one small architecture change between Thunderbird and Athlon XP. Athlon XP now supports Intel SSE operations - but still not SSE2 as used in the Pentium 4. This probably doesn't help Prime95 since prefetch, which _is_ relevant, was already supported by all variants of Athlon CPUs. But it might be worth telling a system running Prime95 on an Athlon XP that it's actually running on a Pentium III just in case that's any faster than the native Athlon code. With the large multipliers used by current processors, the efficiency of the chipset and the memory have quite a large effect on the performance of a CPU. Moving a CPU between systems can therefore result in changes in performance as measured by benchmarks. You really need to check that the chipsets and the memory configurations are the same before you can compare benchmark timings in any meaningful way. Note particularly that e.g. 256 MB can be made up of one bank of 256 MBit, two banks of 128 MBit or four banks of 64 MBit RAM chips; expect a performance difference of 5% - 7% between these configurations even if the chip access speeds & timings are identical. More banks are faster. > > Do we have to consider now Intel/P4 as the best platform (at least for > prime95)? For LL testing using mprime/Prime95: That seems to have been the case for some months now; it's SSE2 which makes the difference. A P4 running Prime95 is well over twice as fast as a T'bird running at the same clock speed. I would expect the same to be the case for any other application which has been specially coded to take advantage of SSE2. There probably are examples, especially in the area of multimedia, but I can't think of any offhand. For general work (including trial factoring): Any variant of Athlon will be significantly faster than P4 running at the same clock speed. At clock speeds up to 1.2 GHz, PIII may be a little faster than Athlon. Especially the new "Tualatin" PIII processor with 512KB cache. However (given suitable software) other processors may be _much_ more efficient in terms of work done per clock cycle than any of the mainstream PC processors. PowerPC, Alpha and especially Itanium spring to mind. AFAIK none of these run above 1GHz yet, though they can be found as the basis of some impressively powerful workstations. AMD do have a point that raw CPU speed is no longer a good indicator of overall system performance, let alone the performance on a particular benchmark task, which can be further influenced by extraneous factors like the efficiency of the graphics card. Regards Brian Beesley _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers ------------------------------ Date: Sun, 14 Oct 2001 13:40:28 -0700 (PDT) From: Francois Gouget Subject: Re: Mersenne: AthlonXP On Sun, 14 Oct 2001 bjb@bbhvig.uklinux.net wrote: > On 14 Oct 2001, at 7:30, Jean-Yves Canart wrote: > > > According to latest benchmarks (http://www.mersenne.org/bench.htm), > > AthlonXP seems to be slower than the Thunderbird. Does anybody have a > > technical explanation ? > > The Athlon XP lies about its speed. Remember the old Cyrix trick? In the benchmarks they appear to be sorted by MHz nonetheless. So this is not a factor. There must be some other explanation. [...] > Having said all that, AFAIK the basic core of the Athlon XP is much > the same as the Thunderbird: it is fabbed at 0.13 microns instead > of 0.18 microns, Nope. It is still 0.18 microns (see Anandtech). If you have a source claiming otherwise I would like to see it. They plan to switch to 0.13 early next year. Then, they should be able to increase the frequency big time. > which means keeping it cool should be a bit easier. They say it runs 20% cooler. It would probably run much cooler if they had switched to 0.13 microns. The reason they provide for the lower power consumption, is small architectural optimizations. But what I find most interesting is its low power consumption when idle. They introduced it for the laptop market but AFAIK it is also present in the regular desktop processor. This poses a kind of dilemna since the energy used to run prime-net is no longer energy that would have been wasted otherwise. So you have to make a choice between preserving the environment and running prime-net (to some extent). [...] > There is one small architecture change between Thunderbird and > Athlon XP. Athlon XP now supports Intel SSE operations - but still > not SSE2 as used in the Pentium 4. This probably doesn't help > Prime95 since prefetch, which _is_ relevant, was already supported > by all variants of Athlon CPUs. Well, they introduced other architectural improvements but none that are relevant to prime-net: auto prefetch (prime-net uses explicit prefetch), low power consumption when idle (i.e. when you're not running prime-net), less fragile packaging, moderately useful thermal diode (does not prevent the processor to burn when the heat sink falls). > But it might be worth telling a system running Prime95 on an Athlon > XP that it's actually running on a Pentium III just in case that's > any faster than the native Athlon code. Why would it make more of a difference with the XP than with other Athlons? [...] > Note particularly that e.g. 256 MB can be made up of one bank of 256 > MBit, two banks of 128 MBit or four banks of 64 MBit RAM chips; > expect a performance difference of 5% - 7% between these > configurations even if the chip access speeds & timings are > identical. More banks are faster. Hmmm, you need to distinguish motherboards that merely have multiple memory slots, from motherboards that have more than one data path to the memory. The only motherboards that I know of that can do the latter are some RDRAM based motherboards and the Nvidia nForce. In all other cases (the more common one?) putting multiple DIMMs should not affect performance one way or another. > > Do we have to consider now Intel/P4 as the best platform (at least for > > prime95)? > > For LL testing using mprime/Prime95: > > That seems to have been the case for some months now; it's > SSE2 which makes the difference. A P4 running Prime95 is well > over twice as fast as a T'bird running at the same clock speed. [...] Yes, AMD better implement SSE2 in their processors soon. - -- Francois Gouget fgouget@free.fr http://fgouget.free.fr/ Stolen from an Internet user: "f u cn rd ths, u cn gt a gd jb n cmptr prgrmmng !" _________________________________________________________________________ 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 #892 ******************************