Mersenne Digest Thursday, April 12 2001 Volume 01 : Number 839
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Date: Tue, 10 Apr 2001 18:53:51 +0200
From: "Tobias" <[EMAIL PROTECTED]>
Subject: Mersenne: A question about ECM
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Hello everybody,
I am interested in factoring Fermat numbers and I checked on the page: =
http://www.mersenne.org/ecmf.htm. Can I help ECM factoring the number =
F(14) for like bound #1 44,000,000? Or is that bound already taken by =
someone. In other word if I use prime95 and do ECM factoring of F(14) on =
bound 44,000,000 will I test the same curves as somebody else who =
already is testing that. Sorry if this is a not relevant question for =
this group but I could not find any relevant information anywhere.
Best Regards,
Tobias
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<DIV><FONT face=3DArial size=3D2>
<P>Hello everybody,</P>
<P>I am interested in factoring Fermat numbers and I checked on the =
page: <A=20
href=3D"http://www.mersenne.org/ecmf.htm"><FONT=20
size=3D2>http://www.mersenne.org/ecmf.htm</FONT></A>. Can I help ECM =
factoring the=20
number F(14) for like bound #1 44,000,000? Or is that bound already =
taken by=20
someone. In other word if I use prime95 and do ECM factoring of F(14) on =
bound=20
44,000,000 will I test the same curves as somebody else who already is =
testing=20
that. Sorry if this is a not relevant question for this group but I =
could not=20
find any relevant information anywhere.</P>
<P>Best Regards,<BR>Tobias</P></FONT></DIV></FONT></DIV></BODY></HTML>
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Date: Tue, 10 Apr 2001 10:07:05 -0700
From: "Paul Leyland" <[EMAIL PROTECTED]>
Subject: RE: Mersenne: A question about ECM
It is relevant here, and you need not worry about repeating other work.
The ECM implementation chooses an elliptic curve randomly each time it
is run --- at least, that's what it's supposed to do. If the random
number generator is any good at all, you have an entirely negligible
chance of choosing a curve that has already been used.
Paul
-----Original Message-----
From: Tobias [mailto:[EMAIL PROTECTED]]
Sent: 10 April 2001 17:54
To: [EMAIL PROTECTED]
Subject: Mersenne: A question about ECM
Hello everybody,
I am interested in factoring Fermat numbers and I checked on the
page: http://www.mersenne.org/ecmf.htm
<http://www.mersenne.org/ecmf.htm> . Can I help ECM factoring the number
F(14) for like bound #1 44,000,000? Or is that bound already taken by
someone. In other word if I use prime95 and do ECM factoring of F(14) on
bound 44,000,000 will I test the same curves as somebody else who
already is testing that. Sorry if this is a not relevant question for
this group but I could not find any relevant information anywhere.
Best Regards,
Tobias
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Date: Tue, 10 Apr 2001 15:10:31 -0400
From: Nathan Russell <[EMAIL PROTECTED]>
Subject: Re: Mersenne: A question about ECM
On Tuesday 10 April 2001 12:53, you wrote:
> > Hello everybody,
>
> I am interested in factoring Fermat numbers and I checked on the page:
> http://www.mersenne.org/ecmf.htm. Can I help ECM factoring the number F(14)
> for like bound #1 44,000,000?
You can, however there is still plenty of work to be done with the bound
11,000,000, and you are somewhat more likely to find a factor using that
bound (that said, F(14) is quite possibly the least likely number to be
factored in the forseeable future of any that GIMPS is now working on).
> Or is that bound already taken by someone. In
> other word if I use prime95 and do ECM factoring of F(14) on bound
> 44,000,000 will I test the same curves as somebody else who already is
> testing that.
No, that's not a concern - Prime95, and the other 'official' GIMPS clients,
use a random-number generator to determine which curves to test. I don't
know the exact periodicity of the generator being used, but I'm sure it's
high enough that the CPU time lost due to duplicate curves is a very minor
concern.
> Sorry if this is a not relevant question for this group but I
> could not find any relevant information anywhere.
No problem.
> Best Regards,
> Tobias
Nathan Russell
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Date: Tue, 10 Apr 2001 20:20:12 +0200
From: "Tobias" <[EMAIL PROTECTED]>
Subject: Mersenne: Another question about ECM
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Hi and thank you mr Leyland for the reply
I have another question. If you are doing ECM factoring on a Fermat =
number with prime95 should you check the "Factor 2^N+1" box, since =
"Every factor of a Fermat number fermat(n) has the form 2^(n+2) * k + 1, =
k >=3D 2"?
Best Regards,
Tobias
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<DIV><FONT face=3DArial size=3D2>Hi and thank you mr Leyland for the=20
reply</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>I have another question. If you are =
doing ECM=20
factoring on a Fermat number with prime95 should you check the "Factor =
2^N+1"=20
box, since "Every factor of a Fermat number fermat(n) has the form =
2^(n+2)=20
* k + 1, k >=3D 2"?</FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=3DArial size=3D2>
<P>Best Regards,<BR>Tobias</P></FONT></DIV></BODY></HTML>
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Date: Tue, 10 Apr 2001 17:51:45 -0400
From: Nathan Russell <[EMAIL PROTECTED]>
Subject: Re: Mersenne: Another question about ECM
On Tuesday 10 April 2001 14:20, you wrote:
> > Hi and thank you mr Leyland for the reply
> I have another question. If you are doing ECM factoring on a Fermat number
> with prime95 should you check the "Factor 2^N+1" box, since "Every factor
> of a Fermat number fermat(n) has the form 2^(n+2) * k + 1, k >= 2"?
Yes you should - and the exponent you should use is the large one (in the
thousands and up) listed on the page, not the Fermat exponent like 12, 14 or
20.
Nathan
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Date: Tue, 10 Apr 2001 21:04:14 +0100
From: Gareth Randall <[EMAIL PROTECTED]>
Subject: Mersenne: Thermal shock in CPUs.
Dear All,
I've been thinking about the temperature fluctuations in a processor, and recalled the
large and rapid changes in processor temperatures that some list members have reported
when the floating point unit is activated.
So my open question is: Do sudden temperature changes cause physical harm to CPUs,
especially those that have only recently been turned on?
Given that integrated circuits do not physically wear out, there are only two failure
modes:
1. Decomposition of gates and other structures by thermal diffusion of doping agents.
2. Thermal stress. i.e. repetitive expansion and contraction due to turning on and off
over time causes cracks to appear leading to failure.
To my understanding, thermal expansion and contraction is the most important failure
mode, and indeed machines that are run continuously are generally more reliable than
those that are turned on and off each day.
So:
1. Those who are lucky enough should run their machines continuously 24 hours. (Hey,
you wanted an excuse to do that anyway?)
2. Are there merits in delaying the running of prime programs by a few minutes after
turning on machines? For instance, a scripted startup could include a plain "sleep
120;" to allow the CPU to warm up slowly before the intense calculations begin.
Yours,
======= Gareth Randall =======
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Date: Tue, 10 Apr 2001 20:50:39 -0500
From: Shane & Amy Sanford <[EMAIL PROTECTED]>
Subject: Re: Mersenne: Thermal shock in CPUs.
>So my open question is: Do sudden temperature changes cause physical harm
>to CPUs, especially those that have only recently been turned on?
Yes it does but.... this depends on your processor & cooling methods to a
certain extent. It's generally accepted that sudden temp changes will
slowly degrade your processor over time but it depends on the severity and
frequency of the changes. A extreme example of this is If you are using
exotic cooling such a peltier (solid state heat pump) without a cold plate,
a metal plate between the peltier & the CPU to buffer the change in heat,
then your core temps will change very very drastically and your processor
MTBF (mean time before failure) will be significantly shorten (down to 6
months to 2 years would seem reasonable). Hence practically everybody adds
a thick cold plate usually copper to minimize this as much as
possible. That is the extreme case in most cases the temp changes are much
less and the frequency of change is less as well so the loss of CPU life
span is fairly insignificant (what does it matter if a CPU designed to last
10 - 15 years is cut down to 7 or 8).
As for as CPU temps on boot up my experience has been that AMD thunderbirds
& durons heat up very very fast so by the time you boot into Windows the
core will be running pretty close to the temps it will be leveling out at
(assuming you are using some form of air cooling). The temps reported by
the BIOS on the other hand takes a while to level out because of the way
the temps are taken. The reason this happens is fairly complicated and
beyond the scope of the question. P3 on the other hand normally hits that
plateau about 10-15 minutes after booting but overall temps in the P3's are
generally less hence the change in temps are generally less as well. So in
my opinion I wouldn't worry about being "careful" with the CPU right after
boot up because the actual boot up & shut down are where the most damage is
done anyway.
Shane
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Date: Tue, 10 Apr 2001 23:24:56 -0400
From: Nathan Russell <[EMAIL PROTECTED]>
Subject: Mersenne: PrimeNet vulnerable to client misconfiguration?
I just checked the PrimeNet status page out of curiousity, to find
that only two 10M-digit numbers are available. When I looked at the
work completed figures, it became rather obvious that one particular
user is running machines that are severely misconfigured. I don't
think this is deliberate abuse, since the user does have several
machines running a few dozen exponents with nothing apparently wrong
with them.
However, the sheer number of assignments involved speaks for itself.
yeager {~} > cat status.txt | grep netconx | wc -l
2292
What I can't help wondering is whether GIMPS should have some
restriction on how many assignments can be checked out by a given
machine per unit time - in this case, the assignments in question are
being run by only two machines, which appear to be repeatedly losing
track of the work assigned to them. One likely possibility is some
sort of automated program that is repeatedly deleting or blanking the
worktodo.ini file.
Perhaps there should be hard limit, after which the user is given an
error or sent an email telling them of the situation?
In this case, there are enough exponents involved to take a top-end
system multiple centuries to complete, and there's no reason why that
should happen without someone contacting PrimeNet to make special
arrangments, if for no other reason than to always have work available
for everyone.
Nathan
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Date: Wed, 11 Apr 2001 02:05:29 -0700
From: "Aaron Blosser" <[EMAIL PROTECTED]>
Subject: RE: Mersenne: PrimeNet vulnerable to client misconfiguration?
There should, at the least, be some "anti-whammy" protection against the
same machine requesting more #'s than it could reasonably handle in a
certain time period (2 years is more than generous, I'd think).
We've seen this before, have we not? Misconfigured scripts of some sort
which keep retrieving new exponents while deleting the ones it already
got. I just recall a few times when some machines like that were
sucking the pool dry.
Aaron
> -----Original Message-----
> From: [EMAIL PROTECTED]
[mailto:mersenne-invalid-
> [EMAIL PROTECTED]] On Behalf Of Nathan Russell
> Sent: Tuesday, April 10, 2001 8:25 PM
> To: [EMAIL PROTECTED]
> Subject: Mersenne: PrimeNet vulnerable to client misconfiguration?
>
> I just checked the PrimeNet status page out of curiousity, to find
> that only two 10M-digit numbers are available. When I looked at the
> work completed figures, it became rather obvious that one particular
> user is running machines that are severely misconfigured. I don't
> think this is deliberate abuse, since the user does have several
> machines running a few dozen exponents with nothing apparently wrong
> with them.
>
> However, the sheer number of assignments involved speaks for itself.
>
> yeager {~} > cat status.txt | grep netconx | wc -l
> 2292
>
> What I can't help wondering is whether GIMPS should have some
> restriction on how many assignments can be checked out by a given
> machine per unit time - in this case, the assignments in question are
> being run by only two machines, which appear to be repeatedly losing
> track of the work assigned to them. One likely possibility is some
> sort of automated program that is repeatedly deleting or blanking the
> worktodo.ini file.
>
> Perhaps there should be hard limit, after which the user is given an
> error or sent an email telling them of the situation?
>
> In this case, there are enough exponents involved to take a top-end
> system multiple centuries to complete, and there's no reason why that
> should happen without someone contacting PrimeNet to make special
> arrangments, if for no other reason than to always have work available
> for everyone.
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Date: Wed, 11 Apr 2001 11:48:42 -0000
From: "Brian J. Beesley" <[EMAIL PROTECTED]>
Subject: Re: Mersenne: Thermal shock in CPUs.
On 10 Apr 2001, at 20:50, Shane & Amy Sanford wrote:
>
> >So my open question is: Do sudden temperature changes cause physical
> >harm to CPUs, especially those that have only recently been turned
> >on?
>
> Yes it does but.... this depends on your processor & cooling methods
> to a certain extent. It's generally accepted that sudden temp changes
> will slowly degrade your processor over time
Eh? A processor with cracking will either work or not. Slow
degradation is more likely aging by thermal diffusion.
>
> As for as CPU temps on boot up my experience has been that AMD
> thunderbirds & durons heat up very very fast so by the time you boot
> into Windows the core will be running pretty close to the temps it
> will be leveling out at (assuming you are using some form of air
> cooling).
If you have a CPU which turns off an inactive floating-point unit,
you may well be only about halfway between ambient and "normal"
operating temperature by the time the system's finished booting. Even
if the boot time is long compared with the thermal inertia time
constant.
> The temps reported by the BIOS on the other hand takes a
> while to level out because of the way the temps are taken. The reason
> this happens is fairly complicated and beyond the scope of the
> question.
Basically (a) there is thermal inertia - _lots_ in the heatsink, (b)
socketed CPUs usually have the thermistor mounted in the well in the
centre of the CPU socket. So it's measuring the temperature of the
socket well, not the heatsink, and certainly not the chip substrate.
And it's only the substrate temperature that actually matters.
Probably a variable fan controlled by the temperature sensor would
help stabilise the substrate temperature, but it's bound to be
stabilised somewhere close to the max temperature, so what you gain
in reduced cracking damage might be more than offset by accelerated
diffusion ageing.
> So in my
> opinion I wouldn't worry about being "careful" with the CPU right
> after boot up because the actual boot up & shut down are where the
> most damage is done anyway.
I agree, but for a different reason - the way CPUs are increasing in
power year on year, that 1.2GHz processor will be pretty puny in two
or three years, so why worry unduly about preserving its life beyond
that?
Regards
Brian Beesley
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Date: Wed, 11 Apr 2001 08:02:44 -0700
From: "John R Pierce" <[EMAIL PROTECTED]>
Subject: Re: Mersenne: Thermal shock in CPUs.
> If you have a CPU which turns off an inactive floating-point unit,
> you may well be only about halfway between ambient and "normal"
> operating temperature by the time the system's finished booting. Even
> if the boot time is long compared with the thermal inertia time
> constant.
indeed, my p3 coppermine goes from 85F when sitting in win2000 doing typical
stuff to 115F in a matter of maybe 60 seconds when running prime95. stop
prime95, and it cools right back down in seconds. Ambient motherboard temp
is 75F with a 68F room temp this morning.
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Date: Wed, 11 Apr 2001 20:53:41 +0100
From: Gareth Randall <[EMAIL PROTECTED]>
Subject: Re: Mersenne: Thermal shock in CPUs.
Further,
There might be two types of "movement" fracture damage occuring:
1. Movement between the substrate and the processor casing. This would be reduced if
the thermal conductivity between these two parts is good, in which case both will
expand together, rather than the substrate rapidly outstripping the still-cold casing.
2. Movement within the substrate itself. I suspect this isn't as significant since the
substrate is thin, but if the floating point "region" expands rapidly while the rest
of the chip is still cold due to heatsink inertia, then forces will be created within
the substrate. Some real numbers might show this to be negligable, but small effects
like this can become the most important when other problems have been solved.
- ----
Ultimately, the forces generated by all movement will be reduced if the temperature
difference between two parts is reduced, hence a slow(er) warming up would be
beneficial.
For instance, a quick jump from 68F to 115F is clearly worse than a quick jump from
85F to 115F, to quote John Pierce's figures.
- ----
I suppose that, overall, thermal damage is not that significant, but unix users who
are concerned can use the following:
su mprime -c "sleep 120; $PRIME_BIN_FILE -d >> $PRIME_LOG_FILE &" &
Yours,
======= Gareth Randall =======
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Date: Thu, 12 Apr 2001 17:50:29 +0200
From: michel claes <[EMAIL PROTECTED]>
Subject: Mersenne: Top producers differents from number of accounts
Dear all,
I have checked somme GIMPs statistics.
I have found some strange things.
http://mersenne.org/ips/topproducers.shtml repports 15898 Accounts.
On http://mersenne.org/primenet/ it is said:
Machines Applied on 20730 Accounts Server Synchronization 21 Dec 2000 03:19
The http://mersenne.org/top2.htm reports
17988 accounts.
Can someone explain me those differences ?
How many persons are participating (15898, 20730, 17988) ?
Thanks in advance.
Michel.
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Date: Thu, 12 Apr 2001 12:42:08 -0400
From: "Brian Last-Name" <[EMAIL PROTECTED]>
Subject: Re: Mersenne: Thermal shock in CPUs.
>So my open question is: Do sudden temperature changes cause physical harm
>to CPUs, especially those that have only recently been turned on?
There are some very silly overclocking people who dip their motherboards
into extremely cold nonconductive liquids. In their efforts, some have
lowered the processor from room temperature to roughly -100 in seconds
without any damage. I personally would like to see someone try cooling by
wind chill, which would avoid the condensation problem and thermal shock
problems, but that is a different ball of wax.
- -Brian Peltzer
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Date: Thu, 12 Apr 2001 18:16:11 +0100
From: Steve <[EMAIL PROTECTED]>
Subject: Re: Mersenne: Top producers differents from number of accounts
On Thu, Apr 12, 2001 at 05:50:29PM +0200, michel claes wrote:
> Dear all,
>
> I have checked somme GIMPs statistics.
> I have found some strange things.
>
> http://mersenne.org/ips/topproducers.shtml repports 15898 Accounts.
But if you coun them there are 20,000+ (yes I've counted them).
It's something that's always puzzled me aswell.
What I think is probably happenning is that it gives a place to every
unique stage withing the process, ie one user with 2000 years worth of
processing in 1st place would count as one, and 15 users all
with 4.251 years worth of processing also counts as one. This is
all just my own guess, so don't take my word for it.
- --
Cheers
Steve email mailto:[EMAIL PROTECTED]
%HAV-A-NICEDAY Error not enough coffee 0 pps.
web http://www.zeropps.uklinux.net/
or http://start.at/zero-pps
6:07pm up 69 days, 18:51, 2 users, load average: 1.22, 1.21, 1.08
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End of Mersenne Digest V1 #839
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