5^421-1 sieving (reservations closed)

[smh]

Does someone have a 64 bit windows executable of gnfs-lasieve4I15e available?

[Batalov]

"You Always Burn the First Pancake"
Catch it or duck!

(which is to say that 175M-176M.bz2 is planted in Malmo.)

[bsquared]

Originally Posted by FactorEyes

Heh. The bottleneck for you may be getting them uploaded, which may take more time than computing them.

A good problem to have, IMO.

Right now the cluster is kinda busy, so I'm only using about 20% of the available CPUs (it will never be 100%, but hopefully 60-80% for some period of time).

p.s. Even this appears to be small potatoes compared to what certain other cluster wielders can bring.

[R.D. Silverman]

Originally Posted by FactorEyes

Heh. The bottleneck for you may be getting them uploaded, which may take more time than computing them.

There is an old quote:

Don't underestimate the bandwidth of a Vokeswagon bus filled with
mag tapes.........

[fivemack]

The postal service is about 1Mbit/second if you stick six DVDs in the package ...

[bsquared]

A VW bus packed full of dual-layer DVD's would be about 2.4GB/s, from where I live to Cambridge, England, neglecting time to load/retrieve data to/from the disks, and assuming I haven't botched something in the estimate.

Although I'm not sure how I'd negotiate the Atlantic Ocean in said VW bus...

Also not sure if I'd be able to generate the 691000 GB of data to fill the disks required to achieve that number. At least with meaningfull information

[xilman]

Originally Posted by R.D. Silverman

There is an old quote:

Don't underestimate the bandwidth of a Vokeswagon bus filled with
mag tapes.........

The version I heard had "panel truck". The fact that we both heard it with "mag tapes" shows how old we are.

When transferring relations, matrices, etc, between home and work I use a 4G memory stick. It takes perhaps 2x30 minutes to load/unload the stick and another 30 minutes in transit on my motorbike. The peak bandwidth is thus 4e9/90/60 bytes/sec, or 740kB/s. My ADSL link is 60kB/s in one direction and 30kB/s in the the other. Sneakernet is thus at least 12 times as fast, peaking at 25 times, than using the interweb thingy. Latency is, admittedly, rather poor.

Unfortunately, the lab where I've been using idle cycles on 20 dual-core machines has been shut down for 6-9 weeks while the entire room is rebuilt. My processing resource has taken a substantial hit until September.

Paul

[smh]

Originally Posted by xilman

The peak bandwidth is thus 4e9/90/60 bytes/sec, or 740kB/s.

Over a short distance. Bandwith would be much lower on longer distances.

Originally Posted by xilman

My ADSL link is 60kB/s in one direction and 30kB/s in the the other. Sneakernet is thus at least 12 times as fast, peaking at 25 times, than using the interweb thingy.

That is something like 512 Kbps / 256 Kbps ADSL? I just did a quick check and i can't even find anything slower than 1500/256 Kbps over here. 20/1 Mbps is quite common and i can't imagine it's much different in the UK.

[xilman]

Originally Posted by smh

Over a short distance. Bandwith would be much lower on longer distances.That is something like 512 Kbps / 256 Kbps ADSL? I just did a quick check and i can't even find anything slower than 1500/256 Kbps over here. 20/1 Mbps is quite common and i can't imagine it's much different in the UK.

Fair enough, but remember that I can ship 1TB (256 sticks) for the same transport cost as 4GB.

Yes 512/256 ADSL. I live sufficiently far from the exchange that that's all British Telecom will provide to my ISP. Cable doesn't go past my house.

However, ADSL2 is coming "soon" (according to BT) and there's a good chance that I'll be able to get several times the present bandwidth. I'm not sure it will reach sneakernet with a single stick though. As long as I want to ship several gigabytes badly enough, that is.

[fivemack]

Originally Posted by Batalov

"You Always Burn the First Pancake"
Catch it or duck!

(which is to say that 175M-176M.bz2 is planted in Malmo.)

Got it, unburnt.

I'm fleeing the country on Saturday, wandering round Scandinavia for a couple of weeks and returning on August 16th, so will let stuff pile up on the server until then.

[fivemack]

I'm back from Scandinavia. The electricians seem to have replaced the outside light in my house without turning the main power off, so the 12M range that I left running on two Q6600s has finished; there's 8M on machines at work which may or may not have finished.

I've updated the list of what I've transferred over; I'm running msieve tonight to see what the figures look like. I ran it a fortnight ago after collecting the first batch of bsquared's relations and got

Sat Aug  2 00:23:02 2008  restarting with 43137861 relations
Sat Aug  2 00:29:25 2008  found 3827072 hash collisions in 42684435 relations
Sat Aug  2 00:29:52 2008  found 1057916 duplicates and 41626519 unique relations
Sat Aug  2 00:30:02 2008  filtering rational ideals above 20119552
Sat Aug  2 00:30:02 2008  filtering algebraic ideals above 20119552
Sat Aug  2 00:36:40 2008  41626519 relations and about 68058770 large ideals

which is a very promisingly low duplication rate.

Sat Aug 16 22:40:00 2008  restarting with 100793240 relations
Sat Aug 16 22:56:58 2008  found 16716495 hash collisions in 97700659 relations
Sat Aug 16 23:00:28 2008  found 5228460 duplicates and 92472199 unique relations
Sat Aug 16 23:01:39 2008  filtering rational ideals above 156041216
Sat Aug 16 23:01:39 2008  filtering algebraic ideals above 156041216
Sat Aug 16 23:01:39 2008  need 26290614 more relations than ideals
Sat Aug 16 23:16:13 2008  92472199 relations and about 86851254 large ideals

I think we're about a third of the way there, and that's with the data from 76 million-Q ranges collated. Given duplication, I still think we probably need to sieve 300 million Q-ranges in total - call it three more months with the present rate of application of compute power.

This computation represents approximately one millionth of one percent of the UK's carbon footprint - eight years at 100 watts per core is 7 megawatt-hours, a megawatt-hour of power from coal is a ton of CO2, and the UK's carbon footprint is 550 megatons per year. If you want a more impressive figure, seven megawatt-hours takes a fourteen-thousand-ton passenger ferry half way from Puttgarden in Germany to Rodbyhavn in Denmark (it's nineteen kilometres; the MOU for the building of the bridge is signed and the bridge should open in 2019)