mersenneforum.org  

Go Back   mersenneforum.org > Factoring Projects > Msieve

Reply
 
Thread Tools
Old 2009-08-04, 23:30   #1
CRGreathouse
 
CRGreathouse's Avatar
 
Aug 2006

172A16 Posts
Default Linear algebra at 600%

This seems wrong to me:
Code:
linear algebra completed 764732 of 125729 dimensions (608.2%, ETA 1027h56m)
CRGreathouse is offline   Reply With Quote
Old 2009-08-04, 23:55   #2
R.D. Silverman
 
R.D. Silverman's Avatar
 
Nov 2003

26×113 Posts
Default

Quote:
Originally Posted by CRGreathouse View Post
This seems wrong to me:
Code:
linear algebra completed 764732 of 125729 dimensions (608.2%, ETA 1027h56m)
Yep! This looks B-A-D. bad. Almost surely a purported basis for one of the
sub-spaces is not orthogonal. Indeed, it probably does not even span the
sub-space.
R.D. Silverman is offline   Reply With Quote
Old 2009-08-05, 00:13   #3
jasonp
Tribal Bullet
 
jasonp's Avatar
 
Oct 2004

3×1,163 Posts
Default

You should restart the linear algebra from scratch. v1.42 has an orthogonality check that runs at regular intervals during the linear algebra, but the matrix has to be of size > 1M for checking to be turned on. I figured that was a good compromise because checkpointing is turned on at that size too, so that you can actually hope to restart from some point beyond the beginning when an error is detected.

Note that in the past, the occurrence of this error has brought the stability of the machine into question. Is your machine overclocked at all?
jasonp is offline   Reply With Quote
Old 2009-08-05, 00:39   #4
joral
 
joral's Avatar
 
Mar 2008

1101112 Posts
Default

If not, I would recommend getting a CD with memtest and letting it run for a while. I was having the same problems, and found it was a faulty DIMM. Of course, that has taken my system from 3GB to 1GB, which is probably limiting my matrix sizes, but..
joral is offline   Reply With Quote
Old 2009-08-05, 00:58   #5
Batalov
 
Batalov's Avatar
 
"Serge"
Mar 2008
Phi(4,2^7658614+1)/2

23·7·163 Posts
Default

The new orthogonality checks + restarts (see below*) will work very well on a slightly compromised computer. (A severely, irresponsibly OC'd computer will not be helped, though.) If errors happen only once/twice a day - you will do fine.

In a way, I have a computer like that, not because of OC'ing but because with 8Gb of memory [which I need, the numbers I am dealing with are that big] doesn't work completely flawlessly with the memory controller and whatnot. For control purposes, 4Gb works excellent for days through: with mprime or with msieve. 8Gb, however, and an error or a couple per day -- at the hottest time of the day, of course. No errors at night.

I have loosened memory timings to 5-6-6 (even though it is rated 5-5-5, 1066) and upped the NB voltages just a tad. The tuning is ongoing, but the calculation simply goes forward. Finished a couple in this regime already. Summer!! It's going to get cooler soon.

___________
*a simple perl script, feel free to make it better:
Code:
 
#!/usr/bin/perl -w
$ret = 1;
while($ret && -e "t.dat.chk") {
$cmd = "./msieve -s t.dat -i t.ini -l ggnfs.log -v -nf t.fb -t 4 -ncr";
$ret = system($cmd);
}
1;
P.S. And no, the system without any changes does not fail neither memtest nor even mprime! Parallel msieve is harder on the memory controller than these tests. And yes, I have a decent cooler. :-)

Last fiddled with by Batalov on 2009-08-05 at 01:03
Batalov is offline   Reply With Quote
Old 2009-08-05, 03:54   #6
CRGreathouse
 
CRGreathouse's Avatar
 
Aug 2006

2×5×593 Posts
Default

Quote:
Originally Posted by jasonp View Post
You should restart the linear algebra from scratch. v1.42 has an orthogonality check that runs at regular intervals during the linear algebra, but the matrix has to be of size > 1M for checking to be turned on. I figured that was a good compromise because checkpointing is turned on at that size too, so that you can actually hope to restart from some point beyond the beginning when an error is detected.
I stopped the process, ran the perl script, and re-started msieve. It looks like it's failing the test repeatedly:
Code:
charles@zed:~/mth/msieve-1.41$ ./msieve

sieving complete, commencing postprocessing
linear algebra completed 2025 of 125729 dimensions (1.6%, ETA 0h 2m)    

linear algebra completed 2014 of 125729 dimensions (1.6%, ETA 0h 2m)    

linear algebra completed 10121 of 125729 dimensions (8.0%, ETA 0h 1m)    

linear algebra completed 4055 of 125729 dimensions (3.2%, ETA 0h 2m)    


linear algebra completed 4048 of 125729 dimensions (3.2%, ETA 0h 2m)    

linear algebra completed 8079 of 125729 dimensions (6.4%, ETA 0h 1m)    

linear algebra completed 14163 of 125729 dimensions (11.3%, ETA 0h 1m)    



linear algebra completed 6072 of 125729 dimensions (4.8%, ETA 0h 1m)    
linear algebra completed 20254 of 125729 dimensions (16.1%, ETA 0h 1m)    
linear algebra completed 6080 of 125729 dimensions (4.8%, ETA 0h 1m)    

linear algebra completed 6072 of 125729 dimensions (4.8%, ETA 0h 1m)    
linear algebra completed 2022 of 125729 dimensions (1.6%, ETA 0h 1m)    
linear algebra completed 4046 of 125729 dimensions (3.2%, ETA 0h 1m)    

linear algebra completed 2025 of 125729 dimensions (1.6%, ETA 0h 2m)    
linear algebra completed 4045 of 125729 dimensions (3.2%, ETA 0h 1m)    
linear algebra completed 2021 of 125729 dimensions (1.6%, ETA 0h 2m)    
linear algebra completed 18212 of 125729 dimensions (14.5%, ETA 0h 1m)    
linear algebra completed 16177 of 125729 dimensions (12.9%, ETA 0h 1m)    
linear algebra completed 6064 of 125729 dimensions (4.8%, ETA 0h 1m)    
linear algebra completed 18207 of 125729 dimensions (14.5%, ETA 0h 1m)    
linear algebra completed 14162 of 125729 dimensions (11.3%, ETA 0h 1m)    


linear algebra completed 10112 of 125729 dimensions (8.0%, ETA 0h 1m)    
linear algebra completed 10109 of 125729 dimensions (8.0%, ETA 0h 1m)    


linear algebra completed 2025 of 125729 dimensions (1.6%, ETA 0h 2m)    
linear algebra completed 4048 of 125729 dimensions (3.2%, ETA 0h 2m)    
linear algebra completed 8093 of 125729 dimensions (6.4%, ETA 0h 1m)    
linear algebra completed 6072 of 125729 dimensions (4.8%, ETA 0h 1m)    
linear algebra completed 6068 of 125729 dimensions (4.8%, ETA 0h 1m)    

linear algebra completed 6072 of 125729 dimensions (4.8%, ETA 0h 1m)    

linear algebra completed 2023 of 125729 dimensions (1.6%, ETA 0h 1m)
Quote:
Originally Posted by jasonp View Post
Note that in the past, the occurrence of this error has brought the stability of the machine into question. Is your machine overclocked at all?
Not overclocked at all (neither the memory nor the CPU). My browser has been crashing a lot recently though, not sure if that's related. I'm running 64-bit Ubuntu if it matters.

Last fiddled with by CRGreathouse on 2009-08-05 at 04:02
CRGreathouse is offline   Reply With Quote
Old 2009-08-05, 04:20   #7
Batalov
 
Batalov's Avatar
 
"Serge"
Mar 2008
Phi(4,2^7658614+1)/2

23A816 Posts
Default

The easiest thing to try without rebooting is the "mprime -m", and then invoke torture test option.
Batalov is offline   Reply With Quote
Old 2009-08-05, 04:41   #8
CRGreathouse
 
CRGreathouse's Avatar
 
Aug 2006

2×5×593 Posts
Default

I rebooted into memtest, and it looks like my (not that new) RAM is bad. I pulled out the offending sticks and am retrying. Edit: It worked just fine -- it seems only the memory was an issue. I guess it makes sense that it took until the linear algebra phase to notice this.

Hmm, I guess it's time to look up Corsair's warranty information. I bought it 4-5 weeks ago, do you think they'll replace it?

Last fiddled with by CRGreathouse on 2009-08-05 at 04:45
CRGreathouse is offline   Reply With Quote
Old 2009-08-05, 07:25   #9
Batalov
 
Batalov's Avatar
 
"Serge"
Mar 2008
Phi(4,2^7658614+1)/2

23×7×163 Posts
Default

They should.
Patriot did -- for a 2x2Gb, when I got the same effect as you. Usually they will not cross-mail, of course. And do start the formal RMA process.
(My trick of getting a particular contact person's email off of the Patriot forum was effective. Some other people who write to the generic RMA email boxes usually complain that there's no answer for a while.)
____

Your avatar reminds me of my original avatar and a quote to go with it:
"The Eagle never lost so much time as when he submitted to learn from the Crow." /W.B./

Last fiddled with by Batalov on 2009-08-05 at 07:31
Batalov is offline   Reply With Quote
Reply

Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
Resume linear algebra Timic Msieve 35 2020-10-05 23:08
Has anyone tried linear algebra on a Threadripper yet? fivemack Hardware 3 2017-10-03 03:11
restarting nfs linear algebra cubaq YAFU 2 2017-04-02 11:35
Linear algebra proof Damian Math 8 2007-02-12 22:25
Linear algebra in MPQS R1zZ1 Factoring 2 2007-02-02 06:45

All times are UTC. The time now is 11:03.

Mon Oct 26 11:03:55 UTC 2020 up 46 days, 8:14, 0 users, load averages: 2.17, 2.19, 2.02

Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.

This forum has received and complied with 0 (zero) government requests for information.

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation.
A copy of the license is included in the FAQ.