mersenneforum.org  

Go Back   mersenneforum.org > Other Stuff > Archived Projects > NFSNET Discussion

 
 
Thread Tools
Old 2006-02-15, 09:14   #1
fivemack
(loop (#_fork))
 
fivemack's Avatar
 
Feb 2006
Cambridge, England

3×19×113 Posts
Default What kind of computer _is_ colossus?

Very few of the computer names in the nfsnet participant list give any indication of what the hardware is; I think that information is collected but not given out.

On the other hand, the most obvious feature of the list is cage's computer 'colossus', which has about fifty times the throughput of my G4/1400 Mac Mini, and ten times the throughput of any other computer on the table; it's performing about a third of the searching on its own.

Is this spare time on a remarkably underused large SMP box, or something more interestingly exotic like a fairly standard PC with lots of memory running lattice rather than line sieving?

On a different note, what kind of extra performance do people with dual-core systems see when running two copies of NFSNET? Sieving is proverbially cache-unfriendly, so I'd fear that the memory bandwidth got constricted.
fivemack is offline  
Old 2006-02-15, 13:04   #2
R.D. Silverman
 
R.D. Silverman's Avatar
 
Nov 2003

22·5·373 Posts
Default

Quote:
Originally Posted by fivemack
Very few of the computer names in the nfsnet participant list give any indication of what the hardware is; I think that information is collected but not given out.

On the other hand, the most obvious feature of the list is cage's computer 'colossus', which has about fifty times the throughput of my G4/1400 Mac Mini, and ten times the throughput of any other computer on the table; it's performing about a third of the searching on its own.

Is this spare time on a remarkably underused large SMP box, or something more interestingly exotic like a fairly standard PC with lots of memory running lattice rather than line sieving?

On a different note, what kind of extra performance do people with dual-core systems see when running two copies of NFSNET? Sieving is proverbially cache-unfriendly, so I'd fear that the memory bandwidth got constricted.

I get about a 20% throughput increase when 2 copies of my lattice siever
on my (hyper-threaded) 3.4GHz IA-32. (versus running one copy)
Of course one needs enough memory to run 2 copies.
R.D. Silverman is offline  
Old 2006-02-15, 15:24   #3
Jushi
 
Jushi's Avatar
 
Sep 2005
UGent

22×3×5 Posts
Default

Quote:
Originally Posted by fivemack
Is this spare time on a remarkably underused large SMP box, or something more interestingly exotic like a fairly standard PC with lots of memory running lattice rather than line sieving?
It's actually a 33-node cluster. They are all Pentium4 3.0GHz machines with 2GB of RAM, running Gentoo Linux. It shows up as one big computer on NFSNET because we use openMosix, which distributes jobs across our cluster, but the jobs still look like they are running on the server node. So NFSNET "sees" a big SMP machine instead of a cluster.

It belongs to the Pure Math department of Ghent University. Currently it's completely idle, but not for long anymore, when I'll start wasting time on the ABC-conjecture.
Jushi is offline  
 

Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
A Different Kind of a Computer a1call Miscellaneous Math 3 2017-06-29 11:15
What kind of number is pepi37 Information & Answers 2 2015-05-21 20:50
Yes, Virginia, there _is_ a largest prime number! R.D. Silverman Data 82 2013-08-14 15:58
So, is this some kind of record or what? schickel Forum Feedback 18 2011-01-22 20:29
A Kind of Solitaire davar55 Puzzles 7 2007-09-21 11:24

All times are UTC. The time now is 21:33.


Tue Oct 26 21:33:06 UTC 2021 up 95 days, 16:02, 0 users, load averages: 1.86, 2.03, 1.83

Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, 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.