Mersenne Digest Monday, March 27 2000 Volume 01 : Number 711
----------------------------------------------------------------------
Date: Fri, 24 Mar 2000 18:40:45 -0800
From: "John R Pierce" <[EMAIL PROTECTED]>
Subject: Re: Mersenne: L2 Cache size
> I do wonder what the speeds would be like for Prime95/NTPrime on a 1MB vs.
> 2MB Xeon... Anyone have the chance to test that out?
I just got my hands on a dual P3-Xeon 600MHz 256kB cache 133Mhz bus machine
at work, running Linux. I'll have to play with some benchmarking next week.
- -jrp
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------------------------------
Date: Sat, 25 Mar 2000 02:35:34 -0500
From: "David Campeau" <[EMAIL PROTECTED]>
Subject: Mersenne: The recent popularity of Factoring
Hi,
I was looking at the PrimeNet's World Test Status and in the recent couple
of days, the factoring assignment went from ~10000 to ~13000. I put my
detective cap and went digging in the Assignment Report.
Seeing who the majority of the factoring exponent were assigned to reminded
me of a previous message to the list.
Sorry if this response is long in coming but...
- ----- Original Message -----
From: "Geoffrey Faivre-Malloy" <[EMAIL PROTECTED]>
To: "Wojciech Florek" <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>
Sent: Sunday, February 06, 2000 11:12 AM
Subject: (censored) :-P
> > I'm an impatient person in a way. I like my exponents finished in a few
>
> Me too :) That's why I factor. I've got about 8 machines factoring (from
> PII 266 all the way up to PIII 500). Still...someone has managed to push
me
> down to number 4 on the factoring top 100. I'll catch up though! :)
>
I bet you are going to catch up... with 3212 exponent assigned to you :-)
Mr. Blosser should be ashamed of is previous setup, it was nothing compared
to you :-)
GeoffreyF Anderson 3
GeoffreyF Build 12
GeoffreyF Chandler2 14
GeoffreyF Christy 10
GeoffreyF EDWARDS 13
GeoffreyF ELBuild1 680
GeoffreyF Goldberg 14
GeoffreyF PDuck 2422
GeoffreyF Server 7
GeoffreyF Tiffany 12
GeoffreyF Tony 12
GeoffreyF Whistler1 6
GeoffreyF Whistler2 7
3212
I think your name imagination is running short :-) or is this a case of
"Houston, I think we have a problem!"
Best regards,
David Campeau,
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------------------------------
Date: Sat, 25 Mar 2000 11:14:37 +0100
From: "Hoogendoorn, Sander" <[EMAIL PROTECTED]>
Subject: RE: Mersenne: V20.1.1 P-1 Factoring
At 07:48 PM 3/24/00 +0000, Brian J. Beesley wrote:
>Did the first start - or finish Stage 1 - at a time of day when
>memory to run stage 2 was not available?
And George Woltman wrote:
>Both day and night settings would need to be 8MB to omit stage 2.
>If day is 8MB and night is 32MB then prime95 waits until nighttime
>to run stage 2.
Prime95 started to do the P-1 factoring after i upgraded, and before
i changed the available nighttime memory to 32MB.
Stage 1 did finish in nighttime, so there would be enough available
memory for stage 2.
Does this mean that the bound for stage 2 is determined on the available
memory when stage 1 is started, or is this because the available nighttime
memory was still at 8 mb when it started the exponent?
Sander
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------------------------------
Date: Sat, 25 Mar 2000 07:53:36 EST
From: "Nathan Russell" <[EMAIL PROTECTED]>
Subject: Re: Mersenne: The recent popularity of Factoring
David Campeau wrote:
>I was looking at the PrimeNet's World Test Status and in the recent couple
>of days, the factoring assignment went from ~10000 to ~13000. I put my
>detective cap and went digging in the Assignment Report.
>
>Seeing who the majority of the factoring exponent were assigned to reminded
>me of a previous message to the list.
>
>Sorry if this response is long in coming but...
>
And Geoffrey Faivre-Malloy
> > > I'm an impatient person in a way. I like my exponents finished in a
>few
> >
> > Me too :) That's why I factor. I've got about 8 machines factoring
>(from
> > PII 266 all the way up to PIII 500). Still...someone has managed to
>push
>me
> > down to number 4 on the factoring top 100. I'll catch up though! :)
> >
>
>I bet you are going to catch up... with 3212 exponent assigned to you :-)
I would suggest that, if this person wants to climb the regular list, he
switch to double-checking, switching over two or three machines a day. This
would gain him credit twice as fast /and/ he would still climb in the
rankings daily, or very nearly so.
>Mr. Blosser should be ashamed of is previous setup, it was nothing compared
>to you :-)
>
> GeoffreyF Anderson 3
> GeoffreyF Build 12
> GeoffreyF Chandler2 14
> GeoffreyF Christy 10
> GeoffreyF EDWARDS 13
> GeoffreyF ELBuild1 680
> GeoffreyF Goldberg 14
> GeoffreyF PDuck 2422
> GeoffreyF Server 7
> GeoffreyF Tiffany 12
> GeoffreyF Tony 12
> GeoffreyF Whistler1 6
> GeoffreyF Whistler2 7
>
> 3212
>
>
>I think your name imagination is running short :-) or is this a case of
>"Houston, I think we have a problem!"
I don't honestly know what to say... The real reason some of us might be
annoyed is that there are machines out there, such as 486's and low
Pentiums, that cannot deal with the current 10 M LL tests, or even, in the
case of the 486s and some K-6s, the 5-6 M doublechecks. Fortunately, I do
not have such a machine, however those who do would be understandibly, if
maybe not rightly, annoyed that someone with large numbers of fast machines
that can easily do LL work has chosen to not only do factoring, but to cache
an amount of factoring work that would normally take GIMPS as a whole months
to finish.
Regards,
Nathan Russell
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------------------------------
Date: Sat, 25 Mar 2000 15:44:56 -0500
From: George Woltman <[EMAIL PROTECTED]>
Subject: RE: Mersenne: V20.1.1 P-1 Factoring
Hi,
At 11:14 AM 3/25/00 +0100, Hoogendoorn, Sander wrote:
>Prime95 started to do the P-1 factoring after i upgraded, and before
>i changed the available nighttime memory to 32MB.
>
>Does this mean that the bound for stage 2 is determined on the available
>memory when stage 1 is started,
The stage 2 bound is determined AT THE TIME YOU CHOOSE
TEST/CONTINUE based on the MAXIMUM of the daytime and
nighttime available memory settings. Thus, if you change your
available memory settings you might want to choose Test/Stop and
Test/Continue if the program is currently running P-1. Perhaps I
need to make this happen automatically for the final version 20.
Regards,
George
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------------------------------
Date: Sat, 25 Mar 2000 16:56:29 -0500
From: George Woltman <[EMAIL PROTECTED]>
Subject: Re: Mersenne: The recent popularity of Factoring
Hi,
At 02:35 AM 3/25/00 -0500, David Campeau wrote:
>I was looking at the PrimeNet's World Test Status and in the recent couple
>of days, the factoring assignment went from ~10000 to ~13000.
>
> GeoffreyF ELBuild1 680
> GeoffreyF PDuck 2422
GeoffreyF tried the FactorOverride undocumented feature on these two
machines. This feature promptly reserved a few thousand exponents
and never returned them to the server.
The undoc.txt file was not clear that this feature must not be used
with the primenet server. It is meant for those few individuals that are
factoring exponents above 20 million. I have upgraded the undoc.txt
file to make this clear.
Scott and Brad at entropia.com - can you unreserve the 3000 exponents
that are assigned to these two machines?
Regards,
George
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------------------------------
Date: Sat, 25 Mar 2000 22:11:06 -0000
From: "Brian J. Beesley" <[EMAIL PROTECTED]>
Subject: Re: Mersenne: The recent popularity of Factoring
On 25 Mar 00, at 2:35, David Campeau wrote:
> I was looking at the PrimeNet's World Test Status and in the recent couple
> of days, the factoring assignment went from ~10000 to ~13000. I put my
> detective cap and went digging in the Assignment Report.
>
> Seeing who the majority of the factoring exponent were assigned to
> reminded me of a previous message to the list.
Before we get too hot under the collar, perhaps we should consider
the possibility that there is a bug somewhere which is causing excess
exponents to be allocated. The user concerned may have triggered this
by running factoring assignments on a fast system, but...
Note that there is a maximum size for the worktodo.ini file. What
would happen if the worktodo.ini file was filled with assignments so
that no more could be fitted in, but that the work queued was still
less than the amount specified? I think there is at least a
possibility that the program would continue to request assignments
from PrimeNet in a doomed attempt to get to the required outstanding
work quota. If I'm right then the majority of the recently assigned
factoring exponents won't be in "live" worktodo files on any system &
are therefore likely to expire in due course.
Why has this hit now? There are several possible explanations, but at
least one which should be looked at is any recent change in the
estimate for factoring time. Other possibilities would be a system
upgrade and/or the fact that the factoring time (to a given depth) is
_inversely_ proportional to the exponent.
Given that P-1 factoring assignments (when introduced) will also be
"short" there may be a need to review the client/server linkage to
reduce the possibility of accidents.
I would urge the user concerned to report what happened and also to
take any steps neccessary to prevent a repetition. I'd suggest
halving the "days of work" value as a first step.
Regards
Brian Beesley
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------------------------------
Date: Sat, 25 Mar 2000 17:33:54 EST
From: "Nathan Russell" <[EMAIL PROTECTED]>
Subject: Re: Mersenne: The recent popularity of Factoring
After this is resolved, should all of us use the manual pages to get rid of
our factoring assignments and get new, lower ones?
I know that I, for one, have two factoring assignments saved up just to
provide a bit of variety between tests
Regards,
Nathan Russell
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------------------------------
Date: Sat, 25 Mar 2000 18:02:34 -0500
From: George Woltman <[EMAIL PROTECTED]>
Subject: Re: Mersenne: The recent popularity of Factoring
Hi,
At 05:33 PM 3/25/00 -0500, Nathan Russell wrote:
>After this is resolved, should all of us use the manual pages to get rid
>of our factoring assignments and get new, lower ones?
There is no need for that. Factoring is far enough ahead of the
first-time Lucas-Lehmer testers that nearly all these exponents will
be trial factored well before the testers start reserving them.
Regards,
George
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------------------------------
Date: Sat, 25 Mar 2000 23:14:40 -0500
From: "Geoffrey Faivre-Malloy" <[EMAIL PROTECTED]>
Subject: RE: Mersenne: The recent popularity of Factoring
Yup. Woops. My apologies to all about reserving so many exponents.
G-Man
> -----Original Message-----
> From: George Woltman [mailto:[EMAIL PROTECTED]]
> Sent: Saturday, March 25, 2000 4:56 PM
> To: David Campeau; [EMAIL PROTECTED]; [EMAIL PROTECTED]; Scott Kurowski;
> [EMAIL PROTECTED]
> Subject: Re: Mersenne: The recent popularity of Factoring
>
>
> Hi,
>
> At 02:35 AM 3/25/00 -0500, David Campeau wrote:
> >I was looking at the PrimeNet's World Test Status and in the
> recent couple
> >of days, the factoring assignment went from ~10000 to ~13000.
> >
> > GeoffreyF ELBuild1 680
> > GeoffreyF PDuck 2422
>
> GeoffreyF tried the FactorOverride undocumented feature on these two
> machines. This feature promptly reserved a few thousand exponents
> and never returned them to the server.
>
> The undoc.txt file was not clear that this feature must not be used
> with the primenet server. It is meant for those few individuals that are
> factoring exponents above 20 million. I have upgraded the undoc.txt
> file to make this clear.
>
> Scott and Brad at entropia.com - can you unreserve the 3000 exponents
> that are assigned to these two machines?
>
> Regards,
> George
>
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------------------------------
Date: Sat, 25 Mar 2000 23:14:36 -0500
From: "Geoffrey Faivre-Malloy" <[EMAIL PROTECTED]>
Subject: RE: Mersenne: The recent popularity of Factoring
> I would suggest that, if this person wants to climb the regular list, he
> switch to double-checking, switching over two or three machines a
> day. This
> would gain him credit twice as fast /and/ he would still climb in the
> rankings daily, or very nearly so.
Why? That's what's great about GIMPS. We all get to choose what we like to
do best. Some like to factor, some like to double check and others like to
do the LL tests. Personally, I enjoy the factoring :)
> I don't honestly know what to say... The real reason some of us might be
> annoyed is that there are machines out there, such as 486's and low
> Pentiums, that cannot deal with the current 10 M LL tests, or
> even, in the
> case of the 486s and some K-6s, the 5-6 M doublechecks.
> Fortunately, I do
> not have such a machine, however those who do would be understandibly, if
> maybe not rightly, annoyed that someone with large numbers of
> fast machines
> that can easily do LL work has chosen to not only do factoring,
> but to cache
> an amount of factoring work that would normally take GIMPS as a
> whole months
> to finish.
Well, I can understand the part about not getting exponents that are lower
numbers and as it's been said, it's because I used the FactorOverride
feature which caused this "problem". But if people are annoyed that I'm
choosing to factor, well, I apologize, but they'll have to get over it. No
offense intended but as I said, that's what is great about GIMPS. We all
get to choose what we want to work on.
G-Man
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------------------------------
Date: Sat, 25 Mar 2000 23:14:40 -0500
From: "Geoffrey Faivre-Malloy" <[EMAIL PROTECTED]>
Subject: RE: Mersenne: The recent popularity of Factoring
> I would urge the user concerned to report what happened and also to
> take any steps neccessary to prevent a repetition. I'd suggest
> halving the "days of work" value as a first step.
The problem was caused by me testing the FactorOverride option and setting
it to an abusrdly low value (56). The end result was that each exponent was
test to to this value then the results were reported and it was removed from
the worktodo.ini. Since it only took a minute for it to reach this high on
the computer it was running, about 60 exponents per hour (sometimes more)
were getting reserved. I say sometimes more because if the exponent had
already been tested to 56 or higher, it would immediately go to the next
exponent.
Is it a bug? not really as it's a previously undocumented feature in
Prime95 and the document now says not to use it with primenet. IMHO, it's a
shame really because it'd be really cool if primenet could take the exponent
back and release it. It would allow those who want to only test to a
certain limit to have the ability to do so (those who have slower machines
maybe).
G-Man
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Date: Sun, 26 Mar 2000 07:39:15 -0000
From: "Brian J. Beesley" <[EMAIL PROTECTED]>
Subject: RE: Mersenne: The recent popularity of Factoring
On 25 Mar 00, at 23:14, Geoffrey Faivre-Malloy wrote:
> The problem was caused by me testing the FactorOverride option and setting
> it to an abusrdly low value (56). The end result was that each exponent
> was test to to this value then the results were reported and it was
> removed from the worktodo.ini. Since it only took a minute for it to
> reach this high on the computer it was running, about 60 exponents per
> hour (sometimes more) were getting reserved. I say sometimes more because
> if the exponent had already been tested to 56 or higher, it would
> immediately go to the next exponent.
Thanks for "coming clean".
>
> Is it a bug? not really as it's a previously undocumented feature in
> Prime95 and the document now says not to use it with primenet. IMHO, it's
> a shame really because it'd be really cool if primenet could take the
> exponent back and release it. It would allow those who want to only test
> to a certain limit to have the ability to do so (those who have slower
> machines maybe).
I'd call it an "unwanted feature". George, I think perhaps the easy
way to handle this would be to check "UsePrimeNet" and refuse to
execute AdvancedFactor assignments if UsePrimeNet=1.
I appreciate the point about slower machines. One way to deal with
this would be a few small changes to Prime95, and a small enhancement
to PrimeNet.
It could go something like this:
Prime95 would have a new parameter for the maximum elapsed time for a
factoring assignment. When it completes to a depth of n bits, before
going on to (n+1) bits it checks if the max elapsed time would be
exceeded. If so, it reports "no factor found to 2^n", signals
PrimeNet that it is abandoning work on this exponent & goes on to the
next assignment. (I think that this is purely client end so far,
since there is already a mechanism to return an unwanted assignment,
both in the manual testing pages and invoked from "Quit Gimps".)
When requesting factoring assignments, Prime95 would tell PrimeNet
the maximum number of bits pre-factored it was prepared to accept
assignments for (this could be calculated approximately from the max
factoring assignment time parameter) . This requires a change to the
server as well as to the client to accommodate, since the server
would have to scan down the list of available factoring assignments
until it found a suitable candidate.
However it is also possible that slower machines with reasonable
amounts of memory could find a role running P-1 assignments, when
they become available. Note that this is dependent on a major change
to the server software, so maybe now is a good time to specify the
relatively minor change needed to accommodate a scheme similar to the
above.
A more general & more secure method of preventing the type of problem
exposed by this incident would be to have the server enforce a quota
for the maximum number of assignments issued to any user/computer id
combo in a particular time interval e.g. 20 per day. Yes, this could
still be got round by anyone determined to cause mischief by changing
the computer id and grabbing another bunch of assignments, but it
would be effective against accidents.
Regards
Brian Beesley
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Date: Sun, 26 Mar 2000 07:09:20 EST
From: "Nathan Russell" <[EMAIL PROTECTED]>
Subject: RE: Mersenne: The recent popularity of Factoring
I appologize for the misunderstanding. The reason I was upset was not
because you used ten machines to do factoring. Even two hundred machines
doing factoring would not have changed the overall balance of GIMPS much.
At the time of my message, I thought that you had deliberately gotten
some-odd thousand exponents. I hope you can understand why that concerned
me.
I do some factoring myself, but I personally prefer the first-time testing,
just because I find it more exciting.
Nathan
>Well, I can understand the part about not getting exponents that are lower
>numbers and as it's been said, it's because I used the FactorOverride
>feature which caused this "problem". But if people are annoyed that I'm
>choosing to factor, well, I apologize, but they'll have to get over it. No
>offense intended but as I said, that's what is great about GIMPS. We all
>get to choose what we want to work on.
>
>G-Man
>
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Date: Sun, 26 Mar 2000 15:11:22 +0200
From: Martijn Kruithof <[EMAIL PROTECTED]>
Subject: Mersenne: merging assignments
Hello,
Currently I am running mprime on NT and Linux on a dual box
separately, now I got a shared partition and I want just to
go on with one assignment a time per cpu. Can I merge the
worktodo files and just copy over all the files to one directory?
(renaming the files from linux to the "standard" fromat) and
making two copies of the mprime program? Or can I give somehow a
parameter on one set of mprimes to finish off the currently buffered
work and not fetch any new work (I already set to avoid getting a big
assignment the MHZ to 25 and hoursaday to 1, work to buffer 1 day on
one set of mprimes).
Kind regards, Martijn
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Date: Sun, 26 Mar 2000 09:34:49 -0500
From: "Geoffrey Faivre-Malloy" <[EMAIL PROTECTED]>
Subject: RE: Mersenne: The recent popularity of Factoring
> Thanks for "coming clean".
Hehehe...I was having fun while it lasted :)
> I'd call it an "unwanted feature". George, I think perhaps the easy
> way to handle this would be to check "UsePrimeNet" and refuse to
> execute AdvancedFactor assignments if UsePrimeNet=1.
I wouldn't say that it's an unwanted feature either. IMHO, I think Primenet
should actually support it. If Primenet would support it and the client
requested factors that hadn't been factored beyond a certain point, then
none of this would have happened :) If primenet supported this feature and
actually released the exponent and would give a new one(s) that weren't
factored that high then it would be possible for those 486 machines that may
be spending a long long time on one factor to specialize in factoring up
to - say 54 bits or something.
> A more general & more secure method of preventing the type of problem
> exposed by this incident would be to have the server enforce a quota
> for the maximum number of assignments issued to any user/computer id
> combo in a particular time interval e.g. 20 per day. Yes, this could
> still be got round by anyone determined to cause mischief by changing
> the computer id and grabbing another bunch of assignments, but it
> would be effective against accidents.
A good idea although I don't know that I'd set the number this low. What if
the person is going on vacation for an extended period of time? A quick
machine can burn through factoring assignments like a knife through butter.
G-Man
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Date: Sun, 26 Mar 2000 09:36:17 -0500
From: "Geoffrey Faivre-Malloy" <[EMAIL PROTECTED]>
Subject: RE: Mersenne: The recent popularity of Factoring
> I appologize for the misunderstanding. The reason I was upset was not
> because you used ten machines to do factoring. Even two hundred machines
> doing factoring would not have changed the overall balance of
> GIMPS much.
> At the time of my message, I thought that you had deliberately gotten
> some-odd thousand exponents. I hope you can understand why that
> concerned
> me.
Oh, absolutely. Makes perfect sense :) I sent George an e-mail about this
several days ago but I've been busy and didn't get his reply until recently
and by then - well, it was too late ;)
>
> I do some factoring myself, but I personally prefer the
> first-time testing,
> just because I find it more exciting.
EXACTLY the point I'm trying to make! See, for me, doing an LL test is like
watching paint dry. I did ONE LL test back in 97 and haven't done another
since :) And before someone says something - yes, there is an exponent that
is assigned to me in the high 33 million range. That's there because I was
trying to do the P1 Factoring which I *STILL* haven't figured out how to get
it to do.
George, with the P1 factoring, does Prime95 only do it if you are doing LL
tests or can this also be done if you are doing a factoring assignment?
G-Man
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Date: Sun, 26 Mar 2000 11:54:54 EST
From: "Nathan Russell" <[EMAIL PROTECTED]>
Subject: RE: Mersenne: The recent popularity of Factoring
>From: "Geoffrey Faivre-Malloy" <[EMAIL PROTECTED]>
>Reply-To: <[EMAIL PROTECTED]>
>To: "Brian J. Beesley" <[EMAIL PROTECTED]>
>CC: <[EMAIL PROTECTED]>
>Subject: RE: Mersenne: The recent popularity of Factoring
>Date: Sun, 26 Mar 2000 09:34:49 -0500
>
> > Thanks for "coming clean".
>
>Hehehe...I was having fun while it lasted :)
>
> > I'd call it an "unwanted feature". George, I think perhaps the easy
> > way to handle this would be to check "UsePrimeNet" and refuse to
> > execute AdvancedFactor assignments if UsePrimeNet=1.
>
>I wouldn't say that it's an unwanted feature either. IMHO, I think
>Primenet
>should actually support it. If Primenet would support it and the client
>requested factors that hadn't been factored beyond a certain point, then
>none of this would have happened :) If primenet supported this feature and
>actually released the exponent and would give a new one(s) that weren't
>factored that high then it would be possible for those 486 machines that
>may
>be spending a long long time on one factor to specialize in factoring up
>to - say 54 bits or something.
I don't know enough about the network to judge your idea on its merits, but
I would say that 54 bits is somewhat low. A 486-33 would finish a 13 M
assignment to 54 bits within easily 2 or 3 minutes. 59 or 60 sounds like a
better idea.
>
>
> > A more general & more secure method of preventing the type of problem
> > exposed by this incident would be to have the server enforce a quota
> > for the maximum number of assignments issued to any user/computer id
> > combo in a particular time interval e.g. 20 per day. Yes, this could
> > still be got round by anyone determined to cause mischief by changing
> > the computer id and grabbing another bunch of assignments, but it
> > would be effective against accidents.
>
>A good idea although I don't know that I'd set the number this low. What
>if
>the person is going on vacation for an extended period of time? A quick
>machine can burn through factoring assignments like a knife through butter.
>
>G-Man
What about this: 300 assignments per month. Going on vacation? No problem.
Your machine grabs, say, 100 assignments out of its quote for the month
and it's set for three or four months.
Just so we know, how long would it take a 1.5 Ghz Athlon to factor 100
assignments through 64 bits? In view of Moore's Law, that's about what we
should figure on.
Regards,
Nathan Russell
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Date: Sun, 26 Mar 2000 18:57:51 -0000
From: "Brian J. Beesley" <[EMAIL PROTECTED]>
Subject: RE: Mersenne: The recent popularity of Factoring
On 26 Mar 00, at 11:54, Nathan Russell wrote:
> What about this: 300 assignments per month. Going on vacation? No
> problem.
If you're running say a dozen systems then 12 * 300 = (IMHO) too
many.
If you're going on vacation, why not feed it some assignments which
will take a reasonable time each to complete?
> Just so we know, how long would it take a 1.5 Ghz Athlon to factor 100
> assignments through 64 bits?
How big are the exponents? The time required will be inversely
proportional to the exponent, though there comes a point where larger
exponents should be factored deeper.
I'm not sure there is much to choose between Athlon and PIII for
factoring speed. Take the figure for a 500 MHz system and divide it
by 3, that will be fairly close.
Personally I think GIMPS/PrimeNet is about spending most of the CPU
time crunching numbers rather than communicating with the server.
IMHO if your system is taking less than about a day to complete a
particular type of assignment, you should switch to something better
suited to your system. There is a great deal of trial factoring to 69
bits or more required for 10 million digit range exponents, I reckon
these would take something of the order of a week each on the (so far
hypothetical) 1.5 GHz system.
Regards
Brian Beesley
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Date: Sun, 26 Mar 2000 15:16:27 EST
From: "Nathan Russell" <[EMAIL PROTECTED]>
Subject: RE: Mersenne: The recent popularity of Factoring
>From: "Brian J. Beesley" <[EMAIL PROTECTED]>
>To: "Nathan Russell" <[EMAIL PROTECTED]>
>CC: [EMAIL PROTECTED]
>Subject: RE: Mersenne: The recent popularity of Factoring
>Date: Sun, 26 Mar 2000 18:57:51 -0000
>
> > What about this: 300 assignments per month. Going on vacation? No
> > problem.
>
>If you're running say a dozen systems then 12 * 300 = (IMHO) too
>many.
Then make it the lesser of 300 assignments per month per machine, or
100/machine-month divided by the base-10 log of the number of machines on
the account. Even someone with 1000 machines running could still do an
assignment a day on each (well, not quite, due to the length of a month, but
I'll round). This, of course, raises the question of how to account for
multi-processor machines. The machine with 2 300 mhz P2 processors can be
safely ignored, but the large university that wants to run mprime in its
free time on its Beowulf cluster can't.
>
>If you're going on vacation, why not feed it some assignments which
>will take a reasonable time each to complete?
There is a point there, but I'm sure there are a few folks who just enjoy
the thrill of finding a factor. There is, we must admit, a pleasure of
discovery to seeing
"Mxxxxxxx has a factor: yyyyyyyyyyyyyyy" several times a month that is
utterly absent from seeing
"Mxxxxxxx is composite" only monthly.
>
> > Just so we know, how long would it take a 1.5 Ghz Athlon to factor 100
> > assignments through 64 bits?
>
>How big are the exponents? The time required will be inversely
>proportional to the exponent, though there comes a point where larger
>exponents should be factored deeper.
>
>I'm not sure there is much to choose between Athlon and PIII for
>factoring speed. Take the figure for a 500 MHz system and divide it
>by 3, that will be fairly close.
>
>Personally I think GIMPS/PrimeNet is about spending most of the CPU
>time crunching numbers rather than communicating with the server.
>IMHO if your system is taking less than about a day to complete a
>particular type of assignment, you should switch to something better
>suited to your system. There is a great deal of trial factoring to 69
>bits or more required for 10 million digit range exponents, I reckon
>these would take something of the order of a week each on the (so far
>hypothetical) 1.5 GHz system.
To my knowledge, the current versions don't allow us to select
factoring-only assignments on the higher exponents. It certainly is an idea
that I feel deserves some discussion, though.
>Regards
>Brian Beesley
Regards,
Nathan Russell
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Date: Mon, 27 Mar 2000 09:49:05 -0500
From: "Geoffrey Faivre-Malloy" <[EMAIL PROTECTED]>
Subject: RE: Mersenne: The recent popularity of Factoring
> Just so we know, how long would it take a 1.5 Ghz Athlon to factor 100
> assignments through 64 bits? In view of Moore's Law, that's
> about what we
> should figure on.
Well, my PII 500mhz can factor 1 number per day to 64 bits. So, it could
probably do 100 in 30 days or so...
G-Man
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End of Mersenne Digest V1 #711
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